How To Install And Wire Car Speaker Crossovers The Right Way

how to install and wire car speaker crossovers featured image

If you want more power & volume, less distortion, or simply to enjoy your music with better sound, you’re going to need to know how to connect speaker crossovers. I’d love to help!

In this article, I’ll cover how to install and wire car speaker crossovers with great results. 

Here’s what you’ll find inside:

  • Car speaker crossover wiring diagrams
  • How to install tweeters with crossovers (including tweeters with built-in crossovers already)
  • How to install a crossover in your car like a pro – tips on installation and mounting
  • Additional helpful info about speakers, impedance, crossovers, and more

There’s a lot to cover so let’s get started!

Contents

How to wire car speaker crossovers (diagram and info)

How to wire car speaker crossovers diagram

How-to and tips for wiring car speakers to crossovers

In order to correctly wire speaker crossovers, you’ll want to do the following:

  • Be sure to plan for having enough speaker wire on hand. Many speakers do come with speaker wire, but more often than not (1) it’s fairly short in length or (2) it’s not great quality. I recommend picking up a roll of 25 feet, 50 feet, or even more to make sure you have enough if running wire from speakers to the crossovers.
  • When connecting the wire, strip about 3/8″ wire from each wire and twist the bare conductors tightly to prepare them for the speaker wire terminals or connectors you’ll be using
  • Be sure to carefully follow the crossover & speaker wire polarity markings. That’s because if one speaker is wired backward vs another, this creates a condition called being “out of phase.” That just means one speaker is working to make sound in the opposite direction of another and can cause some sounds to cancel out, in addition to sounding weird and not as it should.
  • Always use the correct speaker impedance for the crossover. Crossovers are designed to work only with one speaker impedance (Ohms) in most cases. Changing this causes crossover shift which means the crossover’s frequency cutoff changes dramatically and your speakers won’t sound right at all.

Crossovers are normally marked with the correct speaker wire polarity to connect to as well as which speaker you should connect. Often you’ll find an abbreviation like “TW” for the tweeter and “Wf” or “Md” for woofers and midrange/midbass speakers.

Do crossovers have to be wired close to speakers?

Diagram showing crossover wired close to or far away from the speaker

You can install & wire speaker crossover close to the amp or car radio. They don’t have to be installed close to the speakers.

The good news is that yes, you can wire speaker crossovers close to your amp or car stereo if it’s less work. While it’s usually easier to do it where the speakers are when upgrading factory 2-way component speaker systems (since they’re often close to each other in the doors, for example), it’s not important.

example of component speakers installed in car door

It’s generally easier to put a crossover near the component speakers when upgrading (or adding your own) 2-way speaker systems. However, there’s no reason you have to most of the time. When it’s convenient, you might find it helpful to keep the crossover closer to the car stereo or amp, saving the need to do more work or run new speaker wire to go to it.

For example, if you’re upgrading factory-installed tweeters but don’t want to have to hunt down and modify the factory wiring, normally it would require running new speaker wire to them. Instead, you can avoid all that time & headache by wiring them inline behind the head unit, then connecting the new tweeters in place of the old ones.

As long as the speaker wiring is reasonably short (less than 50 feet for each speaker, for example), in the real world it’s not a problem. This is especially helpful for situations like adding bass blockers (inline high-pass crossovers) from an amp to your main speakers.

Just be aware that some vehicles may have factory crossovers installed on the speaker itself (very common for factory tweeters) or somewhere else in the speaker system. It pays to be sure before connecting your own.

How to mount & install car speaker crossovers – 2 great ideas

How to install and mount car speaker crossovers diagram

Once you’ve wired your speaker crossovers, you’ll want to make sure they’re installed and mounted securely. That avoids a lot of problems with them bouncing around and even potentially having a short-circuit if the terminals come close to metal.

As you can see from the diagram above, I’ve provided 2 practical ways:

  1. Mounting crossovers using wire (“zip”) ties: this is definitely one of the easiest and best ways to make sure your crossovers stay put. Not only that, but it saves a lot of time, too. This also works in nearly all vehicles (even boats in many cases!).
  2. Using self-adhesive Velcro tape: Using sticky-back Velcro tape is pretty fast as well, although in hot temperatures the adhesive can lose its strength over time. However, it’s really easy and if you have some Velcro already handy it’s a great way to make good use of it. You can also remove the crossovers without having to cut anything unlike with wire ties.

car speaker crossover installation example using wire ties to mount it

Shown: an example of how I used wire ties to mount a 2-way speaker crossover to the car’s wiring harnesses in the trunk. It’s not “fancy” looking, but still one of the easiest – and best – ways to install crossovers with a lot less hassle.

If you’ve ever bought wire ties you may have noticed that they’re often way too short to wrap around speaker installation parts. One of the installation tricks I use to solve this is by connecting wire ties to each other end-to-end for extra length.

This way, you can use any wire ties (6″, 8″, and other standard lengths stores may have) to get the job done. 

Installer tip: Be sure to get enough wire ties before starting your installation! I recommend buying a standard pack of at least 100 6″ or 8″ zip ties. However, my advice is to buy extra. Having 200 or more is much better especially as you’ll have enough to neaten up your bundled amp or speaker wire runs.

I don’t recommend you bother with the small packs of 25 – 50 or so as you’ll run out of them quickly.

How to wire tweeters with built-in crossovers to speaker crossovers

How to use tweeters with built in crossovers with 2-way speaker crossover diagram

What about using different tweeters with an existing component set or making your own component speaker set using some speakers & crossovers you bought.

The good news is that in most cases if the tweeter impedance matches that of the 2-way crossover this can work.

However, the most important thing here is that you don’t use the built-in tweeter crossovers. You’ll have to remove and/or bypass those.

Generally speaking, most add-on tweeters have one of 3 kinds of built-in or external crossover:

  1. Low-cost 6dB/octave crossover (capacitor) mounted right on the tweeter.
  2. A single capacitor wired inline on one wire.
  3. A 2nd order (12dB/octave) crossover is wired in line with the tweeter wiring or connects to it.

For #2 & #3, you’ll just need to either bypass it and connect the tweeter to speaker wiring & the crossover directly. Case #1 is a bit trickier. You’ll need to either remove the capacitor and solder the speaker wire to the positive tweeter terminal, bypassing it, or solder a jumper wire around it.

Soldering a jumper wire around it will act as a short and the capacitor will no longer be seen by the crossover you’d like to use.

Note that you shouldn’t use existing crossovers on speakers when connecting them to a new crossover. The crossover you’d like to use will behave differently and the sound won’t be correct. (The crossover frequency can change and other kinds of problems pop up)

What happens if I use a different impedance speaker on a crossover?

Crossover shift due to speaker impedance change explained diagram

Diagram showing what happens when you change the speaker Ohm load connected to a crossover: crossover shift occurs. That’s because the crossover frequency is very dependent on the speaker load used. When that changes, the crossover frequency moves (“shifts”) accordingly.

Crossover shift when using different impedance speakers

As I showed earlier, crossovers are based on parts (capacitors and inductors) that work as filters according to the speaker load they’re connected to. Because of this, when you change the speaker impedance you change the crossover frequency and the sound.

You’ll likely notice some sound problems if you do it:

  • A “harsh” sound from woofers or midrange speakers. Tweeters may sound distorted and begin to “break up” at a lower volume than they used to.
  • A “thin”, weak quality to the music.
  • Gaps in the sound ranges you should be hearing.

Speaker crossovers can only be used with the speaker impedance they’re designed for or they won’t sound the same.

As an example, wiring an 8 ohm home speaker to a 4 ohm car speaker crossover won’t work right. In that case the crossover frequency would shift downward 2 x the original value (example: a 3.5kHz crossover frequency would shift to 1.75kHz). That’s because the crossover is designed using math & parts based on using a 4Ω speaker load.

What happens to a crossover when I half the speaker impedance?

When you change the speaker impedance connected to a speaker crossover it can significantly shift the crossover’s cutoff frequency. As a general rule:

  • Halving the speaker impedance (ex.: 8ohms to 4 ohms) doubles the crossover frequency (Ex.: 3.5kHz goes to 7kHz)
  • Doubling the speaker impedance (ex: 8 ohms to 16 ohms) halves the crossover frequency (Ex. 3.5kHz goes to 1.75kHz)

We don’t want this because it allows the wrong range of sound frequencies to pass to the speakers. In the case of tweeters, bass & midrange are bad because they can’t produce it properly. In fact, after a certain power level tweeters can be damaged when driven hard by bass frequencies.

Likewise, many woofers can’t produce high frequency sounds well and often sound really bad when producing it.

If you change the speaker Ohms you’ll have to replace the speaker crossover as well to match.

More great articles to help

You’re in luck! As it turns out, I’ve more fantastic AND free info about tweeters & speakers for you:

Got questions or comments?

Feel free to leave a comment below or you can reach me via my Contact page. Thanks for reading!

How To Wire Tweeters With A Built In Crossover To An Amp

Tweeters – even budget ones – can make a huge difference in your system. However, you may need to know a bit more before getting started. I’d love to help!

In this article, I’ll show you how to wire tweeters with built in crossovers to an amp. I’ve spent hours creating clear & detailed diagrams to help, too.

I’ll cover a lot of topics that really matter:

  • How to wire tweeters with built-in crossovers to an amp
  • Using tweeters with an amp’s built-in crossovers
  • Using your tweeters with a 2-way component speaker crossover
  • Whether or not you can use tweeters with an amp driving subwoofers
Contents

How to wire tweeters with a built in crossover to an amp

how to wire tweeters with built in crossovers to car amp diagram

The great news is that generally, car tweeters with crossovers are fairly easy to connect to amp in your current (or new) mobile audio system.

Note: I’ll use both the words Ohms and its symbol (“Ω”), used often in electronics, when talking about speaker impedance & resistance.

There are a few things to know first:

  • Most of today’s 2 and 4 channel car amp products can handle both a 4 ohm full-range speaker and a 4Ω tweeter connected in parallel at the same time.
  • It’s possible to keep the tweeter’s crossover and use an amp’s built-in crossover later (See related section below for more details).
  • Not only should you never use a tweeter without a crossover, but you also shouldn’t connect a tweeter to subwoofer outputs under normal circumstances. I’ll cover that in more detail later also.
  • You can replace the original tweeter crossover with a better one or use it with a 2-way component speaker crossover if you like.

How to connect tweeters with crossovers to an amp

To connect tweeters with crossovers to an amp, you’ll want use one of the following setups as they’re the most common situations you’ll come across:

  1. Connect them to unused amp channels with a full-range output option: Follow the positive and negative wiring connections on the amp, being sure to match the same speaker polarity at the tweeter (either on the tweeter or marked on the external crossover for those that use an inline one).
  2. “Tapping off” of full-range speakers already connected to the amp: Don’t mix the polarity – for correct sound, be sure connect the tweeter’s positive & negative speaker wiring to the same as the speakers already connected to the amp. To save time, effort, and speaker wire, if it’s convenient you can connect them in parallel at the speakers themselves. You’ll get the same audio signal there as at the amp as long as they’re full-range speakers.
  3. Connect them to unused amp channels: Using a full range RCA output pair from your head unit or use a pair of RCA Y-splitters at the amp to connect the 2nd pair of signal inputs to unused full-range amp channels. You’ll probably need to adjust the amp gain to a good level to match your speakers already in use.

Connecting tweeter wiring

While it’s true that a lot of tweeters come with connectors already on the wire, sometimes it’s just easier (and gives better results) if you use another way to connect the wire. Crimp connectors, for example, give professional results and won’t let you down.

In my experience, some of the connectors (usually slide tab or “spade” type) included with car tweeters are a pain in the behind to deal with. In fact, I rarely use them at all myself.

Keep reading to find out how to connect tweeter speaker wiring with professional results.

Where to install your tweeters

Car tweeter factory installation locations examples

Car tweeters work best when installed where they have a good direction toward your ears. That’s because high-frequency sounds are more directional than bass, for example. As a rule, try to avoid installing them lower in your car or truck. This is one reason you see factory-installed tweeters mounted in vehicle doors or side pillars near the windshield.

It’s not always an option, but when possible it’s best to mount tweeters:

  1. High up near the level of your ears
  2. Pointing towards you

That’s because unlike subwoofers which create huge sound waves that are so big it’s hard to tell where they’re coming from, highs are directional, meaning you’ll get better tweeter performance when the sound is directed towards you and unobstructed.

example of component speakers installed in car door

Example of upgrading factory speakers in a car door with a separate woofer, tweeter, and crossover. Note how the aftermarket tweeter is mounted in the factory bracket, held in with hot glue.

It’s one reason that factory-installed tweeters are placed high in the doors or side windshield pillars from the factory. In fact, high-end home stereo speakers are designed the same way…just that both the tweeter and woofer are placed on the same “plane” or at the same level for best results.

This is also one reason why car component speakers include tweeters designed to be mounted separately – to get the best possible sound by putting them in the best position you can find.

How to connect tweeter wires like a pro installer

Man with sign for how to strip & connect speaker wire properly

For excellent installation quality, I recommend using better connectors when possible. There’s really only a few steps needed and before you know it, you’ll be great at it!

The steps are:

  1. Strip the speaker wire and prepare it for the connector
  2. Insert firmly into the (correct size) crimp connector
  3. Properly and firmly use a crimp tool to permanently connect the wire

Then repeat for the other wires as needed.

How to strip speaker wire

How to strip wire example

To strip speaker wire you can use a number of tools. My recommendation (and preference) is to use an affordable tool called a crimp tool. Most of these not only crimp connectors but can also cut and strip wire.

Stripping speaker wire can touchy at first and take a little bit of practice, but you’ll pick it up quickly after a few tries. The trick is to pinch only the wire’s insulation and not the wire strands themselves.

If you catch the wire inside by squeezing a stripper too hard you’ll likely break the wire and have to start over.

To strip tweeter speaker wire:

  1. Insert the wire in the stripper and close it carefully on the insulation. Use enough force to hold the wire in place and slightly pinch the insulation, but not enough to put force on the wire inside.
  2. Hold the tool & pressure in place firmly so it cannot move.
  3. Pull the wire. The insulation could break off and the exposed wire should remain.

What to know before stripping speaker wire the first time

Some wire types (especially smaller gauges like 20AWG, 24AWG, etc) can be harder to strip without breaking. For your first few tries, practice on some surplus wire that won’t cause you to use up what you need for your tweeter installation.

Image showing ruler next to 1/2 inch stripped wire

I recommend stripping enough to leave about 3/8″ to 1/2″ of bare wire exposed. For crimp connectors, 3/8″ or more should be fine. 

Don’t leave an excessive amount of length because it can stick out of the connector once it’s inserted.

How to use crimp connectors with speaker wire

How to use crimp connectors with wire instruction steps image

Shown: Step by step pictures of how to strip & connect speaker wire using crimp (“butt”) connectors. After stripping the wire, it’s time to use a crimp connector on each one and a tool to crimp them for a long-lasting connection.

Using crimp connectors with speaker wire isn’t very hard – I promise! You’ll get the hang of it after doing a handful of times.

How to crimp speaker wire properly:

  1. Strip the wire leaving 3/8″ to 1/2″ bare wire exposed.
  2. Tightly twist the wire so it can be pushed into the connector properly.
  3. Insert the wire into one end firmly, pushing it into the metal contact inside. Be sure to insert it fully.
  4. Place the connector into the crimp tool in the appropriate position in the tool, near the end of the connector.
  5. Crimp very hard with the tool to make and indentation in the outside of the connector. The internal metal connector should bend inward and make a permanent hold on the wire.
  6. Repeat the same for the other side & speaker wire.
Tip: For best results, once you’re done pull gently on the wire while holding the connector. The wire shouldn’t come out. If it does, you’ve crimped it poorly and will need to do it over again.

What should it look like when you correctly connect speaker wire together?

Closeup example of properly crimped speaker wire

Crimp connectors, also sometimes called butt connectors, are sold in standard colors for the wire gauge sizes they can be used with. Although red is listed as fitting 18 AWG wire, I’ve been using blue butt connectors with 18 AWG speaker wire for years without problems.

You should be able to find a very small package of blue connectors (or an assortment of several sizes) for just a few dollars in general merchandise stores or auto parts stores.

Can you hook up tweeters to the same amp as a subwoofer?

Hooking up tweeters to same amp as subwoofer diagram

Here’s the short answer:

  1. You cannot use tweeters on a monoblock (bass-only) amp or a subwoofer output channel using a low-pass crossover.
  2. You can use tweeters with unused amplifier outputs (channels) that are full-range.

Why can’t you use tweeters on a monoblock sub amp or bass output?

You might not have known it, but nearly all monoblock (single-channel) subwoofer amps are designed only to produce bass. They’re designed just to create a lot of power and drive subwoofers with high volume. There’s no treble (highs) to drive tweeters with at all.

Additionally, using an amplifier’s channel/channels with the built-in low pass crossover means you’re doing the same there as well. For that reason you’ll have just a few options:

  • For multi-channel amps, connect the tweeters to unused full-range amp channels.
  • Connect the tweeters in parallel to the main speakers.

If you only have a single amp for driving the subwoofers and no unused full-range speaker outputs on your amp, there’s no way around it – you’ll have to buy another amp for the tweeters or use your head unit.

Note that head units produce a very small amount of power (about 15W or so per channel) so your tweeters won’t get anywhere near the volume or power your amplified speakers will have.

Can you use the built-in crossovers on an amp with tweeters?

How to use car amp built in crossover with tweeters diagram

Yes, in many cases you can use an amp’s built-in crossovers with your tweeters. In some circumstances, you can even completely replace the tweeter’s crossovers this way!

Additionally, it’s one way to take advantage of your amp’s features and improve the sound.

A few examples are:

  • Using the amp’s 12d/octave crossover improve (or replace) cheaper 6dB/octave crossover some tweeters use.
  • Remove the hardwire tweeter crossover, making installation simpler.
  • Improve tweeter bass blocking without the need for extra parts or work.

How to use tweezers with built-in crossovers with a 2-way crossover

How to use tweeters with built in crossovers with 2-way speaker crossover diagram

I’ve actually run into this situation myself! Let’s say you have some extra tweeters lying around or you’ve got a cool idea for your own 2-way component speaker setup.

Or maybe you’ve got a component speaker system and one of the tweeters is blown, damaged, or broken. What if you could make good use of those extra tweeters or a pair you got a great deal on?

The good news is that in most cases if the tweeter impedance matches that of the 2-way crossover this can work.

However, the most important thing here (the “showstopper” if you will) is that you don’t use the built-in tweeter crossovers. You’ll have to remove and/or bypass those.

What can’t I connect my tweeter crossovers to a 2-way component speaker crossover?

The problem here is that a speaker crossover is designed to connect directly to the speaker “load” (to the speaker impedance, or resistance if you will) directly.

Speaker and tweeter crossovers contain capacitors and inductors. No problem there, but when one crossover is connected to another it changes how they behave. This means (1) the sound will be wrong, and (2) the crossover frequencies will be very wrong.

There’s no way to “fix” that. You’ll have to be sure and remove or bypass a tweeter’s crossover before using it with a speaker crossover it wasn’t originally used with.

More excellent tweeter & speaker articles you can’t miss

You’re in luck! As it turns out, I’ve more fantastic AND free info about tweeters & speakers for you:

Got questions?

Freel free to leave a comment below or visit my Contact page (see the menu at the top). I’d be happy to help you the best I can.

Thanks for your time!

How To Test A Car Stereo – Steps, Diagrams, And More!

How to test a car stereo featured image

As an installer, I saw a lot of used car stereos that customers brought in for installation but ended up being bad. In fact, it happened so often we never would install a car stereo without bench testing it first.

It’s so important to know how to test a car stereo before investing your time & money installing it. That’s why I put together this article – to help you do it yourself!

Here you’ll learn:

  • How to connect & test a car stereo at home & without a car (no, you don’t have to install it!)
  • What you need to power & test a car stereo
  • How to use a computer power supply or car battery as a power source for testing
  • Helpful tips and diagrams to make it easier
  • Common problems with bad car radios
Contents

Basics first: what you need to know before testing a car stereo

Image of teacher instructing how to test a car stereo

The truth is that you don’t really need to “stress test” car stereos. Especially with second-hand and used radios, the real goal is just to be 100% sure your car stereo works before you go through the trouble, time, and effort of installing it.

Fortunately, it’s actually fairly easy to do. You’re going to need to do just a few things:

  • Connect it to a power source properly so it can turn on.
  • Test the speaker outputs: I’ve seen quite a few car stereos where the former owner burned out the speaker outputs due to a poor or incorrect installation.
  • Check the main functions: CD player (if present), radio, Bluetooth, and volume controls.
  • Check for worn-out buttons and other parts.

The great news is that you don’t need to install a car stereo just to check it properly. In fact, you can use just a few simple things and be done in a little while. You’ll need the following:

  1. A test speaker you know is good [see below for suggestions]
  2. +12V to 13.8V power supply (or a vehicle battery – more about that later)

In this article, I’ll cover the steps for testing a car radio, how and which power supplies to use, and the important details to help you before you start. If it’s your first time, I’d plan for spending about 10 to 30 minutes of your free time going through the steps.

Once you’ve done it, however, it’s a lot faster the next time.

Standard car stereo wiring colors: wiring color chart & notes

example of a car stereo wiring harness with standard wire colors

Most – but not all – car radios have a wiring harness that’s color-coded to make installation easier. Power and speaker wiring is usually color-coded while some additional specialty wiring depends on the brand. Note that not all manufacturers follow the wiring color standards so it’s best to check to be sure.

Standard car stereo wiring color chart

Above is a handy chart to help you connect the speaker and power wiring you’ll need when testing a car stereo. Car stereo harnesses you find on most – but not all – brands use standard wiring colors that tell you exactly what they’re for including power, ground, and the speaker connections including positive & negative markings.

This is especially helpful if the radio’s wiring label is torn off or damaged like happens with older radios or if it’s nowhere to be found. Note that some specialty wiring like the dimmer input wire, a mute input for a GPS system, or a few others may use custom colors that only that car radio brand uses. 

Not to worry though as those you won’t normally need to bother with just to test and check out a radio.

Note: Standard car stereo wiring colors are used by many but not all manufacturers. It’s always best to double-check to avoid any problems.

What you’ll need: speaker & power supply notes

Examples of items needed to test a car stereo at home

The good news is that it’s actually pretty simple to get what you need together for testing a car radio. What’s great is that you’ll only need a few parts to get the job done:

  • A test speaker: This can be nearly any full-range or midrange 4 ohm or higher speaker (yes, home stereo 6, 8, and 12Ω peakers will work). Using a tweeter can work but I don’t recommend it as that’ll make it harder to hear sound from the radio’s speaker outputs. You want at least a midrange or full-range speaker.
  • A 12V or 13.8V DC power supply: you’ll need about 1 amp (1A) or more of current for powering on, getting sound from, and checking out most car stereos. You can also use a vehicle battery or computer power supply if you don’t have a 12V DC supply handy.   See the detailed diagram and section below to learn more  
  • A test CD for CD players and/or Bluetooth device: For modern car radios with Bluetooth functions, a smartphone is usually fine to get a Bluetooth audio test source. For CD players it’s best to try out the CD function so you’ll want a disc that you know is good.
  • Electrical tape or similar: not a requirement, but it’s much better to insulate speaker wires you’re not using so they can’t short to the radio’s metal body or each other. Duct tape or other kinds of tape can also work.
  • Needle-nose pliers, cutting pliers, or wire strippers: you’ll need to strip insulation from the radio wiring for testing so a decent tool you can use to remove the wiring insulation is needed here.

Note that while most car stereos use 4Ω speakers, there’s no harm in using a higher impedance (higher Ohm) rating speaker for test purposes.  Any speaker that’s 4Ω or higher will work.

You wouldn’t want to higher impedance speakers every day in your vehicle for the reasons I explain here, but when just checking the speaker outputs anything handy will do.

The main thing is to use a speaker you know for 100% sure is working. Don’t guess – be 100% sure your test speaker is good and plays well when connected to a radio or you could mistakenly think your car stereo has a problem when it doesn’t when testing it.

Note that 1 amp is usually enough to power a car head unit just enough for checking the functionality and getting sound with a test speaker. For driving a car radio with higher power output to multiple speakers, you’ll need more current (a higher amp power supply).

How to test a car radio (diagram and notes)

How to test a car stereo diagram

How to test a car radio

To test a car radio, there are 3 main things you’ll need to do:

  1. Connect the power and ground wiring
  2. Use a test speaker on the speaker outputs to verify they work
  3. Try out any other audio functions you’ll need to use

1. Connecting power to the radio

As I mentioned earlier, you can use a +12V to 13.8V DC power supply for your car radio. Optionally, if you don’t have a 12V supply you can temporarily connect it to a 12V car battery long enough to check out the radio.

In either case, you’ll need to do the following:

  1. Connect the +12V BATT and ACC wires together then to the +12V source. You’ll need both wires to be connected for the radio to turn on. Connect both of these to the +12V output of your supply or the battery.
  2. Connect the ground (“GND”) wire to the negative supply or battery terminal.
The red wire, “ACC” is a +12V input that signals the car stereo to switch on with the ignition, while the yellow “BATT” wire is the main power source. The ACC wire must have power for the radio to work.

Be sure to insulate any unused exposed wires including the speaker wires (more about those later). You don’t want any wires shorting together during testing. For insulating them, electrical tape works great or you can use duct tape or even masking tape carefully if you must. I’d avoid transparent Scotch tape as it tends to come off too easily.

The idea for testing is to temporarily do what you need to for checking that it works. For a real vehicle installation, better connections like crimp connectors should be used.

CAUTION: If using a vehicle battery to power you radio under test, never allow the metal case of the radio near the battery. The metal body is grounded and could cause a dangerous short ciruit if it were to touch a positive wire or terminal.

2. Testing the speaker outputs

Example of the rear of a car stereo installation closeup

Most car stereos use an internal amplifier integrated circuit (IC) chip to provide the power to drive speakers in a vehicle via the speaker wire outputs. Bad speaker outputs due to improper installation (short circuits, low speaker impedance, etc) are a common problem with used car radios.

It’s important to check these and make sure they’re working as expected before bothering to install it. To do so, you can use a test speaker as mentioned earlier with an impedance of 4Ω or above. Even a 6, 8, or even 12Ω speaker you’ve got at home works great for this!

To test the speaker outputs:

  • Connect a test speaker to each speaker wire output pair one at a time, being careful to keep the wires from touching. Keep unused wires insulated with tape or connectors to prevent a short.
  • Turn on the car radio and play music from the FM radio tuner or other functions.
  • A properly working car stereo should have good speaker volume and sound output.
  • Repeat this for all of the remaining speaker outputs.

Note that of all the car radios I’ve tested, it’s not unusual to run across used radios that have no audio from the speaker wiring. 9 times out of 10 this is due to a poor-quality installation where the wires were allowed to touch, someone trying to “get more power” by wiring it the wrong way, or using the wrong impedance (Ohms) speakers.

When a car stereo’s amplifier chip is damaged, it’s permanent and the output transistors fail, no longer able to produce a musical signal. There’s no solution for this outside of paying for a manufacturer repair or just replacing it.

Note: The good news is that generally you shouldn’t need to test RCA jack, if present, on your car radio. These rarely if at all fail. Speaker wiring outputs are the main concern.

3. Testing other functions

Example of testing a car stereo Bluetooth audio function Kenwood KMM-BT518HD

Be sure to test the other functions you’ll use the car radio for: USB audio, CDs, HD radio, Bluetooth, phone direct control (USB cable connection), or others.

Finally, if the speaker outputs appear to be good to go, you’ll want to be sure to check the other main audio functions you’ll be using regularly:

  • The CD player: should be able to load a disc, read the tracks, play it and change tracks, and eject it with no problems.
  • HD radio: if available, be sure it’s working ok. You’ll need to connect an FM radio antenna to try this, however.
  • Bluetooth audio/streaming: you’ll need to connect your smartphone and try this out, making sure it connects normally to a Bluetooth device. (NOTE: If too many devices were already added, you may have to delete one or more from the radio’s memory to free up a new connection)
  • USB/memory card playback: You’ll want to put some .MP3 files on a USB flash drive and/or an SD or microSD card as needed to be sure it can read and playback from them. If a media device fails, there’s likely either a memory card/flash drive formatting problem or the radio itself has a problem.

Also, always be sure to try out most of the buttons to make sure they work properly and aren’t worn out. 

How to know if a car stereo’s controls are in good condition

Rotary volume controls should have a good feel to them and the volume should adjust up or down without a problem. Buttons also should have a good “feel” and shouldn’t be stuck, fail to respond (a sign of a worn-out button switch), or do nothing.

If one or more buttons don’t work or seem right, that’s a red flag that the car radio has either been abused and may not last too much longer. Faceplates can be replaced for brand name head units, but you can expect to spend $50 or more easily for a replacement if you can find one!

One big sign of a car head unit with a ton of use (and wear) is that the printed labels are worn off or show signs of wear already.

How do you hook up a power supply to a car radio?

How to wire a computer power supply to a car stereo diagram

As I mentioned in the beginning, you can use a PC computer “ATX” power supply you have handy to power a car stereo for testing. It’s not that hard as you only need a few steps:

  • Power connections: Cut a +12V wire (yellow) and a ground (black) wire from the main connector. Strip the insulation to leave about 3/8″ to 1/2″ bare wire. Use a crimp connector, solder, or another connector type to join the power supply’s +12V output (yellow) to the radio’s +12V battery wire (yellow). Do the same for the ground wires (black).
  • Supply on control: PC supplies don’t turn on even if the on/off switch on the case is used. A PC motherboard uses a control signal to the “supply on” wire pin. To do the same, you’ll need to find, cut, and jumper this control signal wire to a ground wire either directly or with an on/off switch if you like. ★ See diagram above ★
  • Radio accessory wire: Connect the radio’s accessory/on wire (red) to a +12V power wire from the supply either directly or you can use an on/off switch if you like.

Of course, you can use only one +12V wire from the supply and connect it to both the radio’s ACC and battery wires together if you like. Once power is connected to the radio, connect the “supply on” wire in the diagram to another ground wire as shown. The supply should start and your car radio should turn on. 

Note that some car stereos are switched off by default when they’re first connected to power so you may need to check the power button.

NOTE: Switching off the power supply will cause the radio to lose its “memory” (settings, last station you played, etc) so you may find it easier to use the radio’s power on/off button until you’re finished testing it.

What if my car stereo isn’t working right?

Man thinking about bad car stereo failed testing

I’ve seen some odd problems with used car stereos over the years. It tends to be the same group of problems over and over again – sadly, in a lot of cases, it’s not economical or practical to deal with the headaches.

Here’s a list of problem you might come across and what your options are:

  • No sound from the speaker wiring: If you’re sure you’ve got a good test speaker and there’s nothing else going on, unfortunately, if you don’t have sound the radio’s outputs are likely burned out or have failed. For a few rare models, the internal speaker amplifier can be turned off so you’ll want to be sure that option isn’t causing the problem. Otherwise, it’s most likely the radio is bad and you’ll need to replace it.
  • Won’t turn on with power correctly wired: If you’re 100% sure the wiring is correct, I recommend double-checking for voltage at the pins in the radio’s plug-in harness connector with it unplugged. Some units have an inline fuse you’ll want to check and replace if needed. If the fuse blows again after replacement and the radio still won’t turn on, it has an internal problem and it’s a dud.
  • Controls or volume only partially work/bad buttons/etc: For radios with control buttons like presets, up & down volume, or others that do nothing when pressed, it’s probably because they’re broken or just completely worn out. A clue to this is that there’s no tiny “click” feel when you use them. Bad buttons have no “feel” to them – they’re sort of “stuck” and don’t move. You can try finding a replacement faceplate to remedy this; otherwise, it’s time to find another radio.
  • CD won’t load/can’t read a disc/CD is stuck inside: CD players that can’t read a disc often have a laser lens problem and need repair or adjustment. If a CD can’t be loaded, it’s often a mechanical failure and will require replacement of the whole CD assembly (not easy to find). CDs that are stuck can sometimes be removed safely, but you’ll have to take apart the whole radio, carefully remove the CD, re-assemble it, and try it again. More than likely, however, you’re better off replacing the radio.
  • The faceplate is “loose” and/or it has to be held in place to work: some detachable-face radios can develop a poor connection where the faceplate connects to the main body. You can try some contact cleaner for the faceplate’s electrical contacts, but most likely it’s a bigger problem.

There are always exceptions, but these tend to be some of the most common problems you’ll find when testing car stereos. Thankfully, more and more sold these days use fewer mechanical parts so they’re less likely to have the same problem (aside from wear and tear of the buttons).

If after testing you discover your car stereo isn’t working right and has some issues (especially if there’s no sound from the speaker outputs) my advice is to move on and get a nice condition replacement with modern features.

For under $100 these days you can get excellent sound, features, and customization that didn’t exist a few years ago. It’s not worth the headache of trying to deal with a broken car stereo in most cases (unless it’s vintage and rare items).

More great car audio and speaker articles

Like this article? There’s even more great stuff to see as well!

Got questions or comments? Feel free to leave a comment below or Contact me here.

How To Set Crossover Frequencies For Your Car Audio System

How to set crossover frequency for car audio system featured image

Crossovers are awesome for getting better sound from even cheap speakers. But what are crossovers, how are they helpful, and what are the best crossover settings for car audio?

In this article I’ll show you how to set crossover frequencies for your car audio system along with some other helpful info:

  • How crossovers work and why they make a big difference
  • The best car audio crossover frequency settings (table is provided)
  • Diagrams to show you how to set your car amp crossovers

…and much more, too. There’s a lot to cover so let’s get started!

Contents

What does a crossover do? Crossover frequency, slopes, and more explained

Crossovers and crossover frequencies explained diagram

People tend to talk about crossovers as if they totally “block” sounds you don’t want to go to your speakers. While they sort-of do, in reality, crossovers are filters that greatly reduce the amount of unwanted sound frequencies sent to speakers.

How are crossovers helpful for speakers?

Crossovers are very important for car audio as they help us deal with the poor enclosures they’re used in along with the weaknesses that small speakers have. Some of the most common speaker sizes installed from the factory or sold for aftermarket use like 3.5″, 4″, and 5.25″ sizes can be terrible for playing bass, resulting in bad sound and ugly distortion.

To make matters worse, speakers in cars, trucks, and even boats are often mounted in areas where it’s impossible to get great sound because they leak air and don’t form a good enclosure to deliver sound properly unlike home stereo speaker cabinets. That means they leak air badly and can “bottom out” easily if driven hard with bass sounds, for example.

One reason why crossovers are so helpful there is that we can use them to block terrible-sounding audio frequencies that ordinarily would cause these problems and others, too.

Understanding crossover basics

Car audio crossover examples

When we think about musical signals we don’t always realize the important things going on behind the scenes. In fact, you’ll almost never find a good-sounding speaker system that isn’t using one or more types of crossovers; that’s how important they are for great sound.

A crossover (audio crossover) is an electrical or electronic component circuit made up of parts that react to certain frequencies and designed to eliminate unwanted ranges of sound from reaching speakers.

Crossovers allow a desired range of sound to pass unaltered and effectively block ranges of sound past a limit called the cutoff frequency.

A crossover circuit can be used for only one single speaker channel or combined with another to separate and direct sound the best speakers suited to produce it. In car audio, the most common speaker crossovers are used in 2-way coaxial and component speakers.

Simple speaker crossovers can also be added inline with speakers to block lower-end bass as well.

What are the 3 types of crossovers in car audio?

There are 3 types of crossovers:

  1. Active (electronic) crossovers – work in the signal path (line-level signals)
  2. Passive (speaker) crossovers – work in the amplified speaker path after an amplifier
  3. Digital (software) crossovers – they work with sound in the digital music domain

1. Active (electronic) crossovers

Illustrated diagram of an electronic (active) crossover example

An example of an external (add-on) electronic (active) 2-way crossover. These are basically the same as the electronic crossovers built into many amps you can buy today. Some offer a few more options, but unlike years gone by, they’re less and less important these days. Most amps today include what you’ll need already.

Active crossovers use electrical components such as transistor-based chips called op-amps (operational amplifiers) to behave the same way as their much bigger and much less efficient speaker crossover counterparts.

They offer a lot of benefits (especially their compact size) and can be designed to allow you to choose between using no crossover, a high-pass, or a low-pass easily. Unlike passive crossovers, they do require power to work and change the signal, hence the name “active.”

Active crossovers work with a line-level (RCA) signal either before an amp’s RCA inputs (in add-on external crossovers you can buy) or inside the amp. The signal output of an electronic crossover has to be amplified, unlike speaker (passive) crossovers that you connect between an amp and speakers.

2. Passive (speaker) crossovers

Image showing speaker crossover examples and resistor, capacitor, and inductors

“Passive” crossovers are those that use inductor and capacitors, without a power source, to filter out sounds you don’t want to reach speakers. They’re usually used for smaller speakers like with tweeters, 2-way coaxial speakers, and component speaker systems because they’re relatively affordable in those situations.

Passive speakers aren’t used to block midrange and treble (“highs”) from subwoofers because the size of the inductors needed would be really big – and expensive, too! They’re also much less efficient than electronic ones in that case.

That’s one reason the built-in low-pass subwoofer crossovers in amps are so great.

3. Digital (software-based) crossovers

In dash car stereo with equalizer shown

Software-based equalizers and crossovers use advanced software routines to alter sound in the “digital domain.” That means they can alter the sound (or filter it, as crossovers do) by working only with the digital musical signal. This makes them more complicated but saves spaces & money since it reduces size & the electronics required.

This type is implemented in the software code of home theater receivers, car stereo head units, or digital audio processors. Software-based crossovers usually work by implementing math-based functions that alter the signal output based on its frequency.

It’s a really complicated topic, but the basic concepts aren’t hard to understand. By using special formulas, not only different types of crossovers but also equalizers can be implemented and operate on the musical signal when its represented as a binary digital number.

This is a cost and space-saving feature as there are few, if any, parts needed to make it work. However, it usually takes more specialized microprocessors or digital signal processor (DSP) chips to do so.

What are good crossover frequencies for car audio?

Crossover audio range chart diagram

Within the range of sound your ears can hear, for most cases crossover frequencies typically fall into a small range you’ll likely use for tweeters (high-pass), full range speakers (high-pass), and subwoofers (low-pass).

The truth is, there’s not a “perfect” set of crossover frequencies that work for every speaker in every vehicle. That’s basically impossible because nearly everyone is using different speakers, a different setup, and so on.

However, here are some of the most common frequencies that work well in many cases. 

Recommended crossover frequency table

Speaker/System Type Crossover Freq. & Type Notes
Subwoofers 70-80 Hz (low pass)

Good low-pass frequency range for subwoofer bass & blocking midrange sounds. Best for pure, clear bass sound that "hits."

Car main (full range) speakers 56-60Hz (high pass)

Blocks low-end bass that causes distortion or speakers to "bottom out." Great compromise between full-range sound and midrange bass capability.

Tweeters or 2-way speakers 3-3.5KHz (high pass, or high/low-pass)

Most 2-way or 1-way (tweeter) crossovers use a frequency near this as most tweeters can't handle sounds below this range. Same for woofers above this range.

Midrange/woofer 1K-3.5KHz (low pass)

Woofers and many midrange speakers do not perform well above this general range. They're poor for treble and a tweeter should be added.

3-way system 500Hz & 3.5KHz (Woofer/tweeter crossover points)

Similar to 2-way systems the upper freq. would be the same. Midrange drivers in a 3-way system often do not perform well below 500Hz or 250Hz in many cases.

How to set the crossover frequency for speakers on your amp

How to set crossover frequency on car amp diagram

How to set high pass filter options on your amp (for main speakers)

Most people typically use a car amplifier for one of a few basic systems:

  1. Driving front and rear full range speakers, no subwoofer
  2. Driving front and rear full range speakers plus a subwoofer
  3. Driving a subwoofer

For cases #1 and 2, if your amplifier has a built-in crossover option you can use the high pass crossover to block low end bass that small speakers simply can’t produce well, if at all. The end result is that you’ll be able to drive your main speakers with more volume and lower distortion.

We only want to block that certain range of bass that subwoofers can handle. We don’t want to block bass found in the lower end of midrange like from the vocals in music (for example, around 100-120Hz or so). 60 to 70Hz or so are pretty common crossover frequencies that usually work well.

Adjusting an amp’s high pass crossover

For amplifiers with adjustable crossovers, use the following steps:

  • Turn off equalizer or bass boost functions
  • Set the front channel or front and rear (if using both) crossover switches to “HP” or however they’re labeled for the high pass function.
  • Adjust the crossover frequency control to the lowest setting (this is usually around 50Hz for most amps).
  • Using a small screwdriver, turn it up slightly – about 1/8 of a turn. This should be around the 60-70Hz range.
Note: Not all amplifiers offer an adjustable control. Some (especially ultra-compact models) use fixed frequencies and switches only. In that case, try using the switch position closest to the 60-70Hz high pass frequency range.

How to set subwoofer crossover frequency options

Similarly, do the following to adjust the subwoofer frequency & crossover:

  • Turn off equalizer or bass boost functions
  • Set the crossover switch to “LP” or however it’s labeled for the low pass
  • Adjust the crossover frequency control to the lowest setting (this is usually around 50Hz for most amps).
  • Using a small screwdriver, turn it up slightly – about 1/8 of a turn. This should be around the 70Hz range
  • Adjust as needed: if you’re not happy with the low-end range (the range of bass sound produced), don’t be afraid to adjust the frequency control a bit.
TIP: With decent power and a good speaker enclosure properly matched to the sub, you should have clean, pure bass at this point.

However, I’ve seen many cases where a subwoofer installed in the wrong type of subwoofer enclosure produces bland, poor sound. A crossover can’t fix that problem.

What crossover slope do I need? Does it make a difference?

What crossover slope do you need image of man thinking

In some cases, you’ll be able to choose from a number of crossover slopes (the steepness of the cutoff) on your amplifier or other components. As I mentioned earlier, the slope how effective a crossover is at allowing fewer unwanted sounds to reach your speakers, with higher numbers being more effective.

And as I mentioned ealier, -12dB per octave (“-12dB/octave”) is very common in car audio. While it may seem like the rule of “more is better” applies here, the truth is that most of the time a 12dB or 18dB/octave crossover slope is all you’ll need.

Why do some electronics offer more crossover slopes?

Some amps, head units, and digital processors/equalizers for car audio offer more crossover options for people who want advanced control – especially if you’re working on a high-end sound system. For example, when bi-amping speakers (using an electronic crossover and separate amp channels for the tweeter, the midrange speaker, and so on), you can take advantage of each speaker’s natural behavior and get super-detailed control over the signals you send to them.

That’s a much more advanced topic and worth its own article, by the way.

However here are the basic rules for crossover slopes that will work for 90% of people:

  • A 12/dB setting is good and will do the job in most cases for subwoofers (low-pass) and full-range speakers (high-pass).
  • However, 18dB/octave can be better for some subwoofers depending on your particular subwoofer, the enclosure, and how your vehicle alters the sound. In that case, experiment using the -18dB setting and see how it sounds.
  • 6dB/octave is a bit poor and will allow sounds to pass that can “muddy” the sound and just isn’t good enough for bass speakers. I don’t recommend that in most cases.

Most of the time, the main goal is to have the same cutoff at the same frequency. The goal, in perfect conditions, is that the speakers match up just right so there’s not much overlap in their sound as well as no gaps in the sound.

However, it’s definitely a lot harder in the real world. In my experience, however, 12dB/octave works well and is effective enough to make a big difference in how your system sounds.

More great speaker and crossover info to see

Check out my other great articles you’ll love:

Got any questions I can help with or suggestions? Leave a comment below or sent a message via my Contact page. Thanks!

How To Hook Up A Car Stereo To AC Power – You CAN Do It!

How to hook up a car stereo to AC power featured image

Want to use your car stereo at home? Great news – it’s actually not that hard…if you know what you’ll need.

In this article, I’ll show you how to hook up a car stereo to AC power along with:

  • What you need to know first
  • Clear & easy-to-follow wiring diagrams
  • What kind of AC power adapters or supplies you can use
  • How to wire a computer power supply to a car radio

…and more! There’s no reason to wait so let’s get started.

Contents

First things first: can you hook up a car stereo to a house outlet?

Can you hook up a car stereo to a house outlet image

The quick answer is yes, with the right power supply, you can hook up a car stereo to a house outlet with 120V or even 220V power. You cannot, however, directly connect a car stereo to an outlet.

However, you’ll need to know just a few things to make sure you don’t have any headaches or potentially destroy your car stereo.

Is a car radio AC or DC?

Car radios use direct current (DC) voltage to power their electronics while home electronics use alternating current (AC) with a much higher voltage. In fact, car radios can work down to somewhere around 11 volts DC, with 12V to 14.4V being typical when a vehicle’s engine is running.

The reason car radios use DC power is because automobiles use a DC battery to start and power the engine. While the motor is running an alternator generates AC power that’s changed to DC in order to charge the battery. Batteries store DC power, not AC.

What voltage do home outlets use?

Home AC outlets supply around 120V (volts, or “V”) AC if you’re in the United States and some other countries. Others I’ve been to are even higher at 220V AC. It’s extremely dangerous to try and connect a DC device to AC power – in fact, it can even explode or catch on fire.

What you need is a power supply to safely reduce the high voltage of a home AC outlet to a lower DC voltage that a car stereo can use.

How many amps does a car stereo draw?

The good news is that unlike car amplifiers, a car stereo draws only a few amps. Typical car stereos (depending on the design, features, etc) draw about 2 to 5 amps or so at full power.

I’ve seen some units that have a 10 amp fuse, but that doesn’t mean they use quite that much current. Fuses come in certain sizes so that’s the next closest one the manufacturer needed to use.

Although car stereo manufacturers may advertise them with high power ratings like “50W peak per channel”, in reality, the average car stereo can only put out about 15 to 18 watts RMS per channel.

That’s because they have to work with a +12V supply which limits the power they can deliver.

What is the 12V accessory wire on a car stereo?

Example of car stereo wiring harness power colors, labeled

Car stereos have 3 power wires that have to be connected in order to work:

  1. Ground/negative, “GND”
  2. +12V power/radio memory backup “BATT”
  3. Accessory on, “ACC”

For 99% of car stereo, the 12V accessory wire is a red-colored signal wire that triggers the electronics to switch on. They’re normally connected to a vehicle’s ignition switch accessory wire to turn on and off with the switch. 

It’s necessary to connect this to power on a car stereo. When power is removed from the radio’s accessory wire it turns off and goes into a low power mode.

What can I use to power a car stereo at home?

Car stereo AC-DC power supply examples image

The good news is that 12V power supplies are available if you look in the right place – and one that’s right for hooking up a car stereo to AC power shouldn’t cost much. You just need to know what to look for.

The good news is that it’s usually not hard to find the right kind of supply to power a car stereo at home. You’ll need one with 2 main things:

  • The right voltage: 12V to 13.8V
  • The right current (amps) rating: about 2 to 2.5A for most car stereos and towards 5A for some units that draw more
Tip: 12V supplies will work fine and are also the most common kind. 13.8V AC-DC supplies are used sometimes for powering CB radios and other equipment, so they’ll work fine but aren’t necessary. Don’t go out of your way to use those.

12V supplies are usually a lot more affordable anyway.

You can pick up an AC-DC supply from a variety of places: Amazon, your local electronics store, and you can even use an old PC computer supply (also called an “ATX” supply) you’ve got lying around. I’ll cover that in more detail later.

Can you use a wall adapter for a car stereo?

AC-DC wall outlet adapter example with barrel connector

While you can use a wall adapter to power a car radio with decent results, most are pretty poor and can’t supply many amps and only a little bit of power. You’ll also need to cut the wiring which in some cases can be a little tricky since it’s sometimes very small wire.

Technically, you can use a wall outlet AC-DC 12V adapter, but I don’t recommend it. 

They’re pretty limited in power output and the amperage they can provide (many are less than 1A rated). They’re designed to do things like charge devices or supply low-power devices.

They also don’t have good reserve power and when you start cranking up your car radio the voltage may begin to sag (drop out) and it won’t work well along with the sound breaking up & distorting. You’ll need to find one with enough current (say 2 to 2.5 amps or more if possible) and cut the wiring since most come with a connector attached.

Caution! When using a AC/DC wall adapter, be careful because for some it can be hard to tell which wire is positive and which is negative. 

Always be 100% sure before connecting a radio to avoid a reverse polarity condition as that can damage electronics!

What to know about computer power supplies

Computer power supply 12V current rating examples

PC power supplies are also called “ATX” supplies and can provide lots of current from their 12V wiring. You can see their amps rating on the label like in these examples above.

Computer power supplies are fairly common and are usually priced pretty well (especially used). You won’t need a high-power one.

In fact, even a standard low-end 150W PC power supply will work great for a car stereo! Nearly all of them have more current output than you need.

The drawback, however, is that PC power supplies require a certain (but easy to do) wiring connection in order to turn on. That’s because they’re normally connected to a PC motherboard that provides a control signal for them to work.

Fortunately, there’s an easy workaround you can use that makes them great for a home car stereo system power source.  See my detailed diagram for that further below. 

How do you hook up a power supply to a car radio?

How to wire a car stereo to power & speakers at home diagram

Connecting radio power and ground

To connect a car radio to a power supply you’ll need to do the following:

  • Ground: Connect the radio’s ground wire (black wire) to the (-) power supply output
  • Main power: Connect the radio’s +12V battery wire (usually the yellow wire) to the (+) power supply output
  • Turning the radio on: You can do this by hardwiring the radio’s accessory wire (usually red) to the +12V battery wire or you can use a switch in between.

If you hardwire the accessory wire to the yellow wire (battery power), you can turn the car stereo off with the power supply on/off control. However, while that’s very easy, it comes with a price.

Removing power from the 12V battery wire means the unit will lose its radio tuner settings, audio settings, and any other adjustments you’ve made. Optionally, using a switch to connect the accessory wire as an on/off control is a good idea. Leave the power supply on in this case.

Another way is to simply turn the radio on/off using the power button and leave the power supply on. In either case, when turned off the radio will go into a low-power mode draw less than 0.5 amps when shut off.

Connecting the speaker wiring

Car stereos usually use standard wire colors for speaker connections:

  • White = Front left +, White/black = front left –
  • Gray = Front right +, Gray/black = front right –
  • Green = Left rear +, Green/black = left rear –
  • Violet = Right rear +, Violet/black = right rear –

Just like power wiring colors, not all brands follow these standard colors so always check first!

Remember that car stereos can’t handle a speaker impedance (Ohms speaker load) below 4 ohms. You can, however, use 8 ohm home stereos speakers although you’ll only have 1/2 the rated output power available. I’ll explain that further below.

Never connect 2 ohm speakers for example or wire speaker outputs together as the radio can become hot and permanently damaged. Car stereos aren’t designed to be bridged like a car amp.

How to wire a computer power supply to a car stereo

How to wire a computer power supply to a car stereo diagram

Using an ATX (desktop computer) power supply for a car stereo isn’t hard – in fact, you only need a few steps:

  • Power connections: Cut a +12V wire (yellow) and a ground (black) wire from the main connector. Strip the insulation to leave about 3/8″ to 1/2″ bare wire. Use a crimp connector, solder, or another connector type to join the power supply’s +12V output (yellow) to the radio’s +12V battery wire (yellow). Do the same for the ground wires (black).
  • Supply on control: PC supplies don’t turn on even if the on/off switch on the case is used. A PC motherboard uses a control signal to the “supply on” wire pin. To do the same, you’ll need to find, cut, and jumper this control signal wire to a ground wire either directly or with an on/off switch if you like [See diagram above]
  • Radio accessory wire: Connect the radio’s accessory/on wire (red) to the +12V power wire from the supply either directly or you can use an on/off switch if you like.

Once you’ve connected the +12V and ground wiring to the radio, connect the “supply on” wire shown above to another ground wire as shown. The supply should start and your car radio should turn on. 

As I mentioned earlier, switching off the power supply will cause the radio to lose its “memory” (settings, last station you played, etc) so you may find it easier to use an on/off switch on the accessory wire or turn the radio on & off using the power button.

Don’t forget that a radio uses only a tiny bit of power when turned off so you can leave your power supply running if you like.

How to connect car stereo wires together properly

You’ve got several options for how to connect car stereos wires together properly. I’ll cover a few here. These are:

  1. Using the twist-and-tape method (not something I recommend, but it works “in a pinch”)
  2. Using connectors such as crimp (“butt”) connectors or wire nuts
  3. Soldering the wires together

I’ll cover each in detail.

1. Connecting wire using the twist-and-tape method

Example of speaker wire extended by twisting and wrapping with tape

Although it’s easy to do and cheap (especially if you don’t have many tools around), it’s the least reliable way to connect speaker or car stereo wires together. In my experience, the tape can come off later or the twisted wire may work its way loose at some point.

It’s as easy to do as:

  1. Strip about 1/2 inch insulation from the end of each wire
  2. Twist the bare wire together as tightly as possible, wrapping around each other to help hold them together
  3. Tear off some electrical tape and tightly wind it around the exposed wire and also the wire insulation

2. Connecting wire using crimp connectors

How to use crimp connectors with wire instruction steps image

This is one of the most reliable ways to connect wire and one I’ve used for years for car stereo installations. You’ll need one or more tools to strip your wire and crimp the connectors.

Here’s how:

  1. Strip the wire leaving 3/8″ to 1/2″ bare wire exposed.
  2. Tightly twist the wire so it can be pushed into the connector properly.
  3. Insert the wire into one end firmly, pushing it into the metal contact inside. Be sure to insert it fully.
  4. Place the connector into the crimp tool in the appropriate position in the tool, near the end of the connector.
  5. Crimp very hard with the tool to make press the connector down hard, holding the wire inside permanently.
  6. Repeat the same for the other side & you other wires as needed.

Tip: For best results, once you’re done pull gently on the wire while holding the connector. The wire shouldn’t come out. If it does, you’ve crimped it poorly and will need to do it over again.

Image showing example crimp tool and crimp connectorsExamples of a wire crimping & stripping tool and crimp (“butt”) connectors. Blue is one of the most common and works well with 18AWG wire.

When shopping for crimp connectors you’ll notice they’re available in different colors for different gauges of wire. In most cases, the blue ones are fine for car speaker & radio wiring use. You can also pick up an affordable set that includes the crimp tool and connectors as well.

3. Connecting wire by soldering

Image showing steps for how to solder speaker wire

This is hands-down the most reliable way to extend & splice wires as when done properly soldered wire is extremely strong and is permanent.

How to solder car stereo wires

  1. Cut & strip the wire (at least 1/2″ length of bare wire is needed).
  2. Hold up both ends to form an “X” shape with the wire facing opposite directions.
  3. Hold both ends and tightly twist each end around the other until they’re completely wrapped over each other.
  4. After the soldering iron is hot, apply heat to the wire with the tip. Once heated (after a few seconds usually), apply solder enough so that it has flowed fully through the wire.
  5. Rotate the wire to the other side and apply the solder until all of the wire is fully saturated with solder.
  6. Allow the wire to cool for a few moments.
  7. Tear 2 short pieces of electrical tape. Starting at the insulation and at an angle, tightly wrap the tape until it is fully covered.

It’s important to fully cover the wire once you’re done. That’s to prevent adjacent wires from touching each other and causing a short circuit that can permanently damage the radio’s output stages.

How long does soldering speaker wire properly take?

All in all, you’ll need about 30 minutes to solder a full set of car radio power & speaker wires or a bit less if you’re only connecting the power side.

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How To Wire A Computer Power Supply To A Car Amp

How to wire a computer power supply to a car amp featured image

There’s more than one way to power a car amp in your home. Even so, computer power supplies are easy to find and make a great option – if you know how.

In my detailed guide, I’ll show you how to wire a computer power supply to a car amp. I’ve also put together some great diagrams, tips, and more to help you enjoy your music with less hassle and fewer headaches.

Contents

Can a computer power supply run a car amp? What to know

Can a computer power supply run a car amp man thinking question

Yes, it’s possible to use a PC computer power supply for powering a car amp. 

There are a few things you’ll need to know though. For example, unless you’ve got a higher-power model supply you won’t be able to drive speakers with the same power you could when installed in a car.

Do you need to hook up the remote wire on your car amp?

Yes, a car amp won’t work without a +12V signal on the remote wire terminal. The amp’s internal power supply is controlled by this wire and acts as a shutoff control. Likewise, you’ll want to either turn the power supply on & off as I’ll show you or use the remote wire as a shut off in order to keep the amp from drawing power when not in use.

Computer power supplies also have a particular control wire you’ll need to connect in order to switch the supply on as I’ll show you.

Computer power supply current (amps) & power limits

Computer power supply 12V current rating examples

Examples of the current output (amps) for a typical 200W supply and a higher-power 700W supply. The current output will limit how much power you can get from a car amp.

Computer power supplies are available in a wide range of power output options, with 1500-200 watts being very common but others as large as 700W or more can be found (although they cost a bit more). This is important to know because the current limit of a power supply will limit how much power your car amp can produce.

That means you need to be aware that for higher-power amps you can’t expect to drive speakers with the full power output it’s rated at. The good news that unlike in cars, speakers used in your home use less power for the same volume because vehicle interiors are poor for sound and require more power for good results.

How to power a car amp with a computer power supply (diagram and details)

How to wire a computer power supply to a car amp diagram

Using an ATX (desktop computer) power supply for a car amp isn’t hard – in fact, you only need a few steps:

  • Power connections: Cut the +12V wires (yellow) and the same number of ground (black) wires. Strip the insulation to leave about 3/8″ to 1/2″ bare wire. Twist them together tightly or use a crimp connector (ring terminal, spade terminal, etc) and connect to the amp’s power & ground terminals, being sure not to leave any stray wire strands sticking out to cause a short-circuit.
  • Supply on control: PC supplies don’t turn on even if the on/off switch on the case is used. A PC motherboard uses a control signal to the “supply on” wire pin. To do the same, you’ll need to find, cut, and jumper this control signal wire to a ground wire either directly or with an on/off switch if you like [See diagram]
  • Amp remote wire: There are several great ways to do this and I’ll cover them below.

Once you’ve connected the +12V and ground wiring then ground the “supply on” wire the supply should start up and your car amplifier should power on. There are some cases where you could have a problem, however.

NOTE: If you’re using a high amount of current be sure to use all or nearly all of the yellow +12V wires to connect to the amp. Just like with a car amp installation, you need enough wire conductors to supply higher current without losing voltage from insufficient wiring.

A note about some amps

Larger, very high power car amplifiers can sometimes draw a short current “spike” when they’re first connected to a power source after being disconnected. That’s because they contain large capacitors that, when first connected to power, momentarily draw a huge number of amps.

When this happens it’s possible it could trip the self-protect mode in your power supply. If that happens you can try starting the supply and then wait before turning on the remote wire. You can also leave the supply running when the remote wire is disconnected so the amp’s capacitors don’t discharge when the amp is turned off.

It’s possible you may need a more robust power supply if it happens but it’s not a problem most people should run across.

Remote wire options & examples

How to connect remote wire on car amp used in home diagram

The car amp “remote” terminal uses a low-current +12V input to start its power supply & related circuits. You’ve got a few different options you can use:

  1. Jumper wire:  When connecting the power and ground 12V connections, you can use a small jumper wire from the +12V battery terminal to the remote it so it’s on any time the amp has power. 18AWG or smaller wire is fine (you don’t need a large gauge wire).
  2. Jumper wire + switch: The same as #1 but to control it yourself you can add a simple inline switch on the remote wire. This is helpful if your power supply doesn’t have an on/off switch or you’d rather leave it running.
  3. Home stereo use – RCA converter with remote lead: If you’re connecting the amp to speaker outputs on your home stereo you can use a line level converter with a remote wire output. This will turn the amp on and off automatically with the stereo’s output.

If you’re using a toggle switch on the remote wire you can leave the AC/DC power supply plugged in. When the amp’s remote wire is off (disconnected) the amp will shut off and it won’t drain power.

Using a line level converter with remote wire output

Example of line level converter with remote wire output Axxess AX-ADCT2

An example line-level converter with remote wire output. You’ll need to connect these to 12V power and ground for the internal electronics to work. When the speaker level inputs detect a signal the remote wire output will produce +12V and turn on your amplifier. When the speaker signal is lost it will switch it off automatically.

Connecting a laptop, tablet, or smartphone to the amp for audio

Diagram for how to connect audio signal to a car amp used in your home

What’s great is how many options you have for getting an audio signal to your amp’s inputs. In fact, nearly any analog (non-digital) jack can be used from almost any device. Smartphones, tablets, and laptops can be used either by their headphone jack or via Bluetooth.

Just be aware that not all headphone or audio out jacks are created the same –  some work well and have good sound & volume while others can have low volume and “meh” sound quality. However, the good news that generally speaking they’ll work well and I’ve used this approach several times with no complaints.

Connecting your smartphone or tablet via Bluetooth

You also use an affordably-priced Bluetooth receiver for around $25 from places like Amazon. They offer a direct line output jack or RCA jacks to go into a home receiver and a car amp just as easily.

Be sure to get a decent brand as the generic/no-name brand models tend to have sound quality problems and can produce odd noises between music tracks playing on your phone, for example.

What if I have a laptop with no headphone jack?

Example of a USB to headphone audio adapter

You can use a cheap USB to stereo 3.5mm adapter to get a headphone sized jack to connect an audio signal to your amp. They’re really affordable (under $10 in some cases!) and are a good option if your laptop’s headphone jack is broken or none is available.

If you’re like many people and want to enjoy music, movies, or more from your laptop there’s a problem if you don’t have a line-out or headphone jack – or if it’s just not working. A great option is to use a USB audio adapter as it’ll provide a 3.5mm jack you can connect to your amp’s RCA inputs.

I’ve found some for under $10 available with both the older USB-A and the new USB-C connection as well.

How to connect a car amp to a home stereo

How to connect a car amp to a home stereo diagram

You can also connect your car amp to your home stereo if you like. There are 3 ways to do it:

  1. Home stereo with no RCA output jacks + car amp with speaker level inputs: It’s fairly common for home stereo amps and receivers not to have RCA jacks available to connect to. If your amp has built-in speaker level inputs these can be connected to either an unused pair of speaker terminals or alongside speaker terminals in use.
  2. Home stereo with no RCA output jacks + car amp with no speaker inputs: You’ll have no choice but to use a line level converter in this case. These are car stereo adapters that you connect to speaker wiring or speaker terminals. This will drop the signal down to a level compatible with the amp’s RCA inputs.
  3. Home stereo with full range RCA output jacks + car amp: This is the easiest way but not all home stereos have full-range RCA output jacks. Some only have subwoofer RCA output jacks which are bass-only outputs. Full-range RCA output jacks can be connected directly to the car amp’s RCA inputs.

Image showing examples of line level RCA converters

Line level connectors will let you connect a car amp with no speaker inputs to any home stereo. You can connect these to unused speaker terminals on the receiver or amp as well as in parallel with home speakers already in use.

Dealing with ground loop hum (noise)

Example of an RCA ground loop isolator

You can use a ground loop isolator to break the ground conductor in RCA cables but still carry the audio signal. Since the ground connection can carry the noisy signal that gets amplified this often eliminates ground loop noise.

One thing you might not count on running into is noise. Ground loop noise, which appears as a very annoying 60Hz “hum”, is somewhat common for home stereo equipment. Unfortunately, despite car amps being designed to eliminate it, it can still happen.

One thing you can do is to try using a small gauge wire and connect it between the grounds or metal casing of the car amp, the RCA cables, and the power supply. If the noise disappears you can connect the wire to those points as a solution.

Alternatively, a ground loop isolator can often get rid of it. Connected inline with the RCA cables, they work by physically disconnecting the RCA cable’s ground connection while still sending the audio signal. They’re not expensive, but it’s a good idea to shop carefully as the “el-cheapo” units don’t always carry the entire audio range well and can cause a loss of sound quality you can notice.

Additional reading and helpful guides

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How To Connect & Power A Car Amp In Your Home + Diagrams

How to power a car amp in your home featured image

It might seem puzzling at first, but it’s actually not that hard to connect and power a car amp in your home.

In this detailed guide I’ll show you how along with detailed diagrams anyone can understand.

Here’s what you’ll learn:

  • Car amp power supplies: what voltage & current ratings you need
  • How to wire a computer power supply to an amp
  • How to connect a car amp to a home stereo, smartphone or tablet, or Bluetooth
  • Additional tips to make it easier & offer more options
Contents

First facts: Can I use a car amplifier in my house?

Can I use a car amplifier in my house man thinking image

Yes, it’s possible to use a car amplifier in your house. You can also connect a car amp to any home stereo, your smartphone, and more as an audio source.

There is a catch, though. Because car amps use a different power source than home stereos the biggest problem is getting them the power they need. Not only that, but they use a remote-on wire to turn the amp on & off to avoid draining a car battery – meaning that needs to be dealt with too.

Here’s a list of what we’ll need to cover:

  • Signal inputs: Not all home stereos have RCA line-level jacks, so if you’d like to connect an amp to your home stereo it may require a workaround I’ll show you. You can also connect a car amp to nearly any smartphone or external Bluetooth receiver.
  • Power source: Unlike home stereos powered by an alternating current (AC) electrical outlet, car amps work from a +12V direct current (DC) supply. You’ll need a +12V AC-DC power supply with enough current to run the amp. Not just any AC/DC 12V adapter will do – I’ll cover this below.
  • Turning the amp on/off (remote wire): Home stereos or other audio devices don’t have a remote wire output to switch your amp on and off. However, there are some easy ways to deal with this, too.

You also need to know that:

  • Unless you have all the parts already, you may need to spend a little bit of money to get what you need & get it working. The good news is that most of it is affordable and you can even make use of some power supplies like a computer DC supply you may left over.
  • Retail stores are pretty bad about not having the parts you may need, so you might want to plan ahead and order parts online. You can find many affordably priced parts on Amazon, eBay, and from electronic part suppliers.

Choosing a power supply for car amp use

Example of how to estimate car amp current used

You can estimate how much electrical current (amperage, “amps”) your amp will draw based on its maximum power given in watts RMS. However, the truth is that’s only if you need a lot of power. For casual listening, you can get by with a lot less.

Basically, there are 2 ways to go about choosing a power supply for a car amp:

  1. Getting a “good enough” power supply if you’re not driving the amp hard (fine for casual listening)
  2. Estimating the amp’s current draw based on its power rating (useful for when you want serious amp power)

Of these, #1 makes it a lot simpler. You may be able to use a DC supply you’ve already got handy or a leftover computer power supply (sometimes called an ATX power supply).

What voltage does a car amp need?

Car amps normally work off of a range of voltages, not just 12 volts, although that’s used as a general reference. In fact, as a vehicle’s engine runs the alternator charges the battery and the voltage can range from near 12V to about 14.4V. 

For home use, choose a power supply with a DC output from 12V to 13.8V, with 12V being perfectly fine to use. When shopping most of the higher-current supplies you’ll see are 12V anyhow.

At around 11V or so car amps and other car stereo equipment may shut off so it’s important to have enough voltage available.

What size power supply do I need?

Car amp DC power supply examples

Powering a car amp in your home requires a power supply with a decent amp rating. Standard wall adapters won’t work as they’re very weak (0.5 to 1A, usually). You can find bigger power supplies like a 5 amp model for under $15 if you shop smart. Desktop computer ATX power supplies are cheap, easy to find, and range in power ratings up to 500W or even more.

Quick tip: Computer power supplies can offer 15 amps or even more current output making them a great solution. They’re available in a variety of power ratings such as 150W to 500W or more.  A good ATX power supply will have enough power output for the average person.

Option #1: Getting a “good enough” power supply for casual listening

When not driving an amp & speakers hard, I recommend at least a 2.5A supply for small amps (under 50W/channel). For 4 channels, I’d get a 5A or bigger. If you’d like to have more power, consider getting 15A or above.

You can find a 5A supply for under $15-$20 if you shop around. 10A and 15A supplies are fairly popular so they’re usually under $30-$35 dollars or so. When it comes to much bigger supplies that will let you drive a subwoofer with heavy bass things tend to get expensive. Very high current power supplies are around $100 and above for 30 amps or more.

However, one of the best options is to use a desktop computer power supply (“ATX” power supply) as they’re easy to find and have pretty good power output.

Option #2: Estimating amp current needed for higher power use

If you’re planning to use a car amp to drive speakers hard you’ll need a lot of amperage which you can estimate pretty closely We also need to take into account wasted power to come up with a final number. (All amps waste some power as heat and draw some additional current for that reason)

  • Class D car amplifiers are more efficient and therefore waste less power (and draw less current) than standard class A/B amps.
  • If you’re not sure what class your amp is, it’s probably class A/B. Class D amps normally say so on the amp itself, the box, or sales info. Class A/B types have been so popular for years that it’s a pretty safe assumption.

You can estimate amp current based on the maximum RMS power of the amp. Don’t use “peak” or “maximum” watt power ratings as these are misleading. We need to use the continuous power (RMS) the amp really delivers.

As class D car amps are around 85% efficient and A/B amps are around 65% or so efficient we can use that to estimate the total current an amp would need.

Class D amp example:

Estimate amps used by a 50W RMS x 4 amp:

  1. 4 x 50W = 200W total. (200W/12V) = 16.7A.
  2. Take into account power waste: 16.7A/.85 = 19.6A
Class A/B amp example:

Estimate current used by a 150W RMS x 2 amp:

  1. 2 x 150W = 300W total. (300W/12V) = 25A.
  2. Take into account power waste: 25A/.65 = 38.4A

As you see, to run a car amp at full power you’ll need a pretty big power supply! However, most people don’t so it’s usually a lot less hassle (and less money) to use one of the other supplies I showed examples of.

How to wire a computer power supply to a car amp

How to wire a computer power supply to a car amp diagram

Using an ATX (desktop computer) power supply for a car amp isn’t hard usually. It’s a matter of a few steps:

  • Power connections: Cut several ground wires (black) and +12V wires (yellow) and strip them for about 3/8″ to 1/2″ bare wire. Twist them together tightly or use a crimp connector (ring terminal, spade terminal, etc) and connect to the amp’s power & ground terminals.
  • Supply on control: PC supplies don’t automatically come on even if the side switch is on. Normally a motherboard uses a control signal to the “supply on” wire pin. As shown in the diagram above, you’ll need to jumper the wire by cutting it, stripping it, and either connecting to a ground wire permanently or you can use a toggle switch.
  • Amp remote on wire: As there are several good options for this, I’ll cover this in more detail below. 

Once you’ve connected the supply-on wire to a ground wire the power supply should start and your car amp should work. Note that in some cases, it is possible to have a problem.

Huge, high-power car amplifiers can sometimes have a short current “spike” they draw when first connected to power. In some cases, this can trip the self-protect mode in power supplies. If that happens you can try starting the supply first and then give the remote wire power after a moment.

It’s possible you may need a more robust power supply if that happens as well. This shouldn’t be an issue most of the time, though.

Remote wire options for turning the car amp on

How to connect remote wire on car amp used in home diagram

A car amp’s remote-on input uses a low-current +12V signal that starts its internal power circuitry. There are several good ways to do this:

  1. Jumper the remote on terminal:  When wiring the power and ground 12V connections, you can use a small jumper wire from the +12V terminal to the remote terminal so it’s on any time the amp has power. 18AWG or smaller wire is fine.
  2. Jumper wire + switch: Basically the same, but you can also use a simple inline switch on the remote wire to turn it on/off yourself.
  3. Home stereo use – RCA converter with remote lead: If you’re connecting an amp to speaker outputs you can use a line level converter with a built-in remote wire output. They’ll automatically turn the amp on or off with an input signal present.

If you’re using a toggle switch on the remote wire you can leave the AC/DC power supply plugged in. When the amp’s remote wire is off (disconnected) the amp will shut off and won’t drain power.

RCA adapters with remote wire output

Example of line level converter with remote wire output Axxess AX-ADCT2

Example of a line-level converter with a remote wire output feature. When the speaker level inputs have a signal and it creates a +12V remote on signal. When no signal is detected, the remote wire will go to zero volts and turn the amplifier off. Unlike a regular converter, these need +12V and ground connections to work.

How to connect a home stereo, smartphone, or other audio sources to an amp

What’s great is how many options you have for getting an audio signal to your amp’s inputs. In fact, nearly any analog (non-digital) jack can be used from almost any device. I’ll cover some of the main ones here:

  • Smartphones, tablets, and laptops can be used either by their headphone jack or via Bluetooth (see below)
  • Any home stereo receiver or amp can be used – even vintage ones!

How to connect a smartphone or other device to a car amp (diagram & options)

Diagram for how to connect audio signal to a car amp used in your home

Be aware that headphone jacks can be a good or bad audio source depending on your particular device. Even though they’re usually not quite as good as RCA outputs/AUX output jacks, I’ve had pretty good experiences doing using this with brand name smartphones or tablets.

In fact, I use this method to test a car amp at home.

You also use an affordably-priced Bluetooth receiver for around $25 from places like Amazon. They offer a direct line output jack or RCA jacks for this very reason.

Be sure to get a decent brand as the generic/no-name brand models tend to have sound quality problems and can produce odd noises between music tracks playing on your phone, for example.

How to connect a car amp to a home stereo (diagram & options)

How to connect a car amp to a home stereo diagram

The way you connect your car amp depends on both your home stereo and your car amp’s features. You’ll end up with one of 3 situations:

  1. Home stereo with no RCA output jacks + car amp with speaker level inputs: It’s actually fairly common for home stereos and home theater receivers to have no full-range RCA audio-out jacks. In this case, if your car amp has speaker level inputs built-in these can be connected to an unused pair of speaker terminals or alongside speaker terminals in use. The amp’s speaker level inputs will scale down the speaker signal to a much lower signal the amp needs.
  2. Home stereo with no RCA output jacks + car amp with RCA jacks only: In this case, you’ll have no choice but to use a line level converter used for car audio. Just like in #1 above, these are connected just like speakers to speaker terminals alone or alongside connected speakers.
  3. Home stereo with full range RCA output jacks + car amp: This is the easiest way by far. Unfortunately, not that many home stereos have full-range RCA output jacks. Some only have subwoofer RCA output jacks which are bass-only outputs. Full-range RCA output jacks can be connected directly to the car amp’s RCA inputs, but subwoofer RCA jacks won’t work for full-range music since they only pass bass.

What is a line level (RCA) converter and how do they work?

Image showing examples of line level RCA converters

Shown here are two examples of line level/RCA speaker level converters that work well for home receiver/amp to subwoofer use. Both take a higher voltage speaker level signal and drop it down to a low voltage suitable for the amp’s input section.

Line level converters (also called RCA speaker level adapters) are small adapters that reduce the higher-voltage signals from speaker outputs to a much lower voltage (“line level”) used by a car amp’s RCA jack inputs. They can be connected directly to a ratio, amp, or speaker and provide RCA jack connections.

They’re really useful because they make it possible to connect an amplifier to a signal source that you otherwise can’t.

What to do if you have ground loop noise (humming)

Example of an RCA ground loop isolator

A ground loop isolator you can use to “break” (isolate, disconnect) an amp’s RCA ground connections from that of an audio source to eliminate the electrical path that causes ground loop noise.

Sadly, noise can be a BIG headache when it comes to car amps despite them being designed to prevent it. The same is true that home stereos, too: anything that carries a signal and has a ground connection can create a “ground loop” that gets picked up by the amp and then turned into a very annoying noise you easily hear.

What causes ground loop noise?

Ground loop noise happens when there’s a slightly different potential (a slight difference in voltage) between the ground connections in an amp, stereo, and other components. Despite everything you try, sometimes it’s nearly impossible to eliminate.

In that case, you can try a simple RCA cable ground loop isolator which often solves it. Note that you shouldn’t try to get the cheapest you find because they can negatively affect sound quality.

You can find a good one for $10-$25 or above depending on the brand and features.

Related helpful articles

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How To Connect A Car Amp To A Home Stereo (With Diagrams)

How to connect a car amp to home stereo featured image

Using a car amp…at home? It’s not such a crazy idea after all! While it’s true that it’s not super easy, it’s really not all that hard and you can do it.

In this article, I’ll explain how to connect a car amp to a home stereo with clear diagrams anyone can understand. I’ll also show you all the little things you need to know before you try so you avoid disappointment & headaches.

Contents

First things first: Can a car amplifier be used at home?

Can a car amp be used at home man thinking

The good news is that YES, one way or another, you can definitely connect a car amp to a home stereo.

However, since car amps use a different power source the single biggest challenge is getting enough power to them. They also use a remote-on wire to turn the amp on & off so it doesn’t draw power and kill your battery when installed in a car.

Fortunately, these (and other) problems are fairly easy to deal with. Here’s a list of what you’ll run into when using a car amp at home:

  • Signal inputs: Not all home stereos have RCA line-level jacks, so this may require a workaround to connect to your amp’s audio inputs. Some amps make this pretty easy, however. (This isn’t much of a problem as you’ll see from my diagrams below)
  • Power source: Unlike home stereos that are powered from alternating current (AC), car amps work from a +12V direct current (DC) supply. You’ll need a +12V AC-DC power supply with enough current to run the amp. Not just any AC/DC 12V adapter will do as you’ll see later.
  • Turning the amp on/off: This is actually really easy! You can simply disconnect your DC power supply and let the amp shut off or use a simple switch to turn the amp on and off. I’ll show you how to wire the car amp so it can turn on.

The bad news is that unless you have the parts you need already, you’ll probably have to spend a little bit of money to get it working well.  The good news is that most of what you need can be found and bought new or used but you may need to order some online.

Sadly, retail stores are usually poorly stocked when it comes to power supplies that you can use for a car amp indoors. You’ll have much better luck online at places like Amazon or electronic parts suppliers.

How to use car amp with a home stereo + diagram

How to connect a car amp to a home stereo diagram

The way you’ll connect your car amp depends on both your home stereo and your car amp’s features as I mentioned earlier. You’ll end up with one of 3 situations:

  1. Home stereo with no RCA output jacks + car amp with speaker level inputs: It’s actually fairly common for home stereos and home theater receivers to have no full-range RCA jacks you can connect to the amp. In this case, if you’ve got a car amp with speaker level inputs these can be connected to either an unused pair of speaker terminals or alongside speaker terminals in use. The amp’s speaker level inputs will scale down the speaker inputs to a low signal it can use.
  2. Home stereo with no RCA output jacks + car amp with RCA jack inputs only: In this case, you’ll have no choice but to use a line level converter commonly used for car audio. Just like in #1 above, these are connected just like speakers to unused speaker terminals or alongside an existing speaker set. This will drop the signal down to a very low level that’s used by the amp’s RCA inputs. Note: I strongly recommend getting a decent quality model converter with adjustable outputs for best results.
  3. Home stereo with full range RCA output jacks + car amp: This is the easiest way by far, but not all home stereos have full-range RCA output jacks. Some only have subwoofer RCA output jacks which are bass-only outputs. Full-range RCA output jacks can be connected directly to the car amp’s RCA inputs.

How to connect the remote-on wire on a car amp

How to connect remote wire on car amp used in home diagram

In all cases, you’ll also need to wire the amp with power and a remote-on wire so it can turn on. You can do this one of several ways:

  • Jumper the remote on terminal:  When wiring the power and ground 12V connections, you can use a small jumper wire from the +12V terminal to the remote terminal so it’s on any time the amp has power.
  • Just a jumper wire + switch: Basically the same, but you can also duplicate how a car stereo’s remote on wire works by using a simple inline switch on the remote wire to turn it on/off yourself.

If you’re using a switch you can leave the AC/DC power supply plugged in if you like. When the amp’s remote wire loses its +12V signal, the amp will switch off internally and draw zero power.

Example of line level converter with remote wire output Axxess AX-ADCT2

QUICK TIP: To make things even easier, you can use a line level converter with a built-in remote wire output feature which will automatically turn the amp on or off with the speaker input signal.

Note that these do need a power and ground connection.

What is a line level/RCA converter and how do they work?

Image showing examples of line level RCA converters

Shown here are two examples of line level/RCA speaker level converters that work well for home receiver/amp to subwoofer use.

Line level converters (also called RCA speaker level adapters) are small electronic devices that connect to speaker outputs from an amp or receiver and scale down the higher-voltage signal to a low level (“line level”). The outputs are RCA jacks which can then be connected to an amplifier or subwoofer with RCA jacks.

They’re extremely handy in the car stereo world because they make it possible to connect a stereo without RCA outputs to any amplifier or powered subwoofer. We can also use them for home stereos, too.

How much do line level converters cost?

While you can get the el-cheapo ones for under $10, I don’t recommend those. Expect to spend around $15-25 or so for a good one. No need to spend too much these days as there are lots of good values out there.

What voltage & size DC power supply do I need for a car amp?

Example of how to estimate car amp current used

You can get a rough estimate of the maximum amount of electrical current you’ll need for a car amp using its maximum RMS power as shown here. However, if you’re not using an amp to its full capability you can get buy with a smaller (and less expensive) power supply.

What voltage does a car amp need?

Car amplifiers, when installed in a vehicle, work off of a voltage range as the engine runs. Although we say cars & trucks use a 12V supply, in reality, a car amp is designed to work from somewhere around 11V to 14.4V or so as the alternator in your vehicle raises or lowers it’s output while charging the battery.

Therefore you can use a power supply with a DC output similar to this, but I recommend 12V to 13.8V. Most power supplies you can buy are one of these.

What size power supply do I need?

Car amp DC power supply examples

You’ll need a power supply with a decent amperage (A) rating. Regular wall adapters won’t work as they’re very weak (0.5 to 1 amps or so). You can find 5A supplies for under $15 depending on where you shop. Desktop computer “ATX” power supplies are affordable and available in power ranges up to 500W or more. They’re easy to find but need a certain wiring connection in order to turn on.

In order to figure out how big of a DC power supply you need, you might want to calculate roughly the amount of current your amp will draw at full power. Once we know that, we can take into account wasted power that all amps use up and come up with a fairly accurate number.

Just so you know, class D car amplifiers are more efficient and therefore waste less power (and draw less current) than standard class A/B amps.

If you’re not sure what class your amp is, if it’s a class D amp it’s usually stated on the box or the amp itself. Class A/B amps often don’t state it anywhere. (Many new amps are class D so I wanted to take that into account)

Estimating amp current

You can estimate amp current based on the maximum RMS power of the amp. Don’t use “peak” or “maximum” watts as these don’t reflect the actual continuous power a car amp puts out.

As class D car amps are around 85% efficient and A/B amps are around 65% or so efficient we can use that to estimate the total current an amp would need.

Class D amp example:

Estimating the current used by a 50W RMS x 4 amp, all 4 channels used:

  1. 4 x 50W = 200W total. (200W/12V) = 16.7A.
  2. Take into account power waste: 16.7A/.85 = 19.6A
Class A/B amp example:

Estimating the current used by a 150W RMS x 2 amp, both channels used:

  1. 2 x 150W = 300W total. (300W/12V) = 25A.
  2. Take into account power waste: 25A/.65 = 38.4A

As you can see, to run a car amp at full power you’ll need a pretty big power supply! However, the good news is that it’s only if you really want to drive the amp at full capacity. For lower-power, casual listening, we can get by with a smaller (and thankfully, cheaper) power supply.

Realistic power ratings you’ll need

For just listening to music with decent volume, I recommend at least a 2.5A supply for small amps (under 50W/channel). For 4 channels or higher power ones, I’d get a 5 amp or bigger. If you’d like to have more power, consider getting 15A or above.

You can find a 5A supply for under $15-$20 if you shop carefully. 10A and 15A supplies are fairly popular so they’re usually really affordable, too. However, when it comes to much bigger supplies that will let you drive a subwoofer with heavy bass, for example, those can be expensive: $100 and above.

Connecting 2 RCA stereo outputs to a 4 channel amp

Diagram showing a 2 channel car stereo connected to a 4 channel ampWhat if you’ve got a 4 channel amp? No problem! You’ll still use the same methods shown earlier but you’ll need to jumper either the speaker level inputs or the RCA inputs using “Y” connections to get a signal to the rear channels too.

Most car amps with front & rear speaker level inputs can be wired to 2 speaker input pairs as shown in the diagram here. When using RCA connections, you can pick up a pair of inexpensive female-to-male Y adapters to split the signal from 2 into 4 connections. (Don’t spend too much on Y adapters as you can use a decent pair of cheap ones just fine)

QUICK TIP: Some car amps have a 2/4 channel input switch built in for this purpose. In that case, setting it to the “2ch” position will supply a signal to all 4 channels. For some amps this only applies to the RCA inputs so be sure to check your owner’s manual.

Can I use 8 ohm speakers with a car amp?

4 ohm vs 8 ohm speaker power comparison graph

This graph shows what happens when you use an 8 ohm speaker in the place of a 4 ohm one. The 8 ohm speaker will work – however, it comes with a price. Since the 8 ohm speaker isn’t matched to the 4 ohm car amp, it can only receive up to 1/2 the power output and has a lower maximum volume than a 4 ohm speaker would.

Using 8 ohm home speakers in place of 4 ohm ones with your car amp won’t hurt anything. There’s a catch, however. They’ll only develop 1/2 the power of a 4 ohm speaker meaning lower maximum volume is possible.

For example, if you were to use some home stereo 8 ohm speakers instead of 4 ohm speakers, you’d notice the volume would be a bit lower than when using 4 ohm ones. That’s because a speaker needs more and more power output to increase the volume more and more; also 8 ohm speakers allow only 1/2 the same amount of electrical current to flow vs 4 ohms.

Car amplifiers & car head units don’t have a high voltage supply like home stereos and home amplifiers do. That means they’re designed to use lower impedance (lower resistance) speakers to develop the same amount of power by letting more current flow.

As long as you’re aware of this it’s ok, because they’ll still sound and play fine – you just can’t get the same power and as much volume when you crank it up vs using 4 ohm speakers.

I have a hum (ground loop noise) from the amp. What can I do?

Example of an RCA ground loop isolator

Example of a ground loop isolator you can use to break the ground conductor connection in RCA cables to eliminate ground loop noise.

Unfortunately, noise is a problem with car amps despite them being designed to prevent it. It’s also true that home stereos and amps are known to sometimes create “ground loops” between different electronic components via the RCA cables.

Ground loop noise happens when there’s a slightly different potential (electrical voltage point) between the grounds of an amp, stereo, and other components. Despite everything you try, sometimes it’s nearly impossible to eliminate.

In that case, you can use a ground loop isolator to connect inline in the RCA cables. This usually does the trick. Note that you shouldn’t try to get the cheapest you find because they can negatively affect sound quality.

You can find a good one for $10-$25 or above depending on the brand and features. The good news is that they’re super easy to use: just connect them to the RCA cables and you’re done!

More great articles you’ll love

There’s lots more great stuff to see! Here are some excellent articles that have helped many others, too:

Let me know what you think!

Have questions or comments? Just let me know below! You can also contact me directly here.

How To Hook Up A Car Subwoofer To A Home Stereo (With Diagrams!)

How to hook up a car subwoofer to a home stereo featured image

Thinking about putting that extra car sub to good use? Maybe you’re wondering if it’s possible to hook up a car subwoofer to a home stereo or amplifier at all.

The good news is that yes, in many cases you can use a car sub with a home stereo. However, it’s not as easy as just wiring them up any old way.

I’ll tell you what you need to know and provide some helpful diagrams. Let’s get started.

Contents

Can I hook up a car subwoofer to my home stereo?

Can I hook a car subwoofer to a home stereo? Man thinking image

The quick answer is that it depends. There are several basic things you need to understand first before you try. These are important, too…so don’t be careless or you could damage your home receiver or amplifier.

You can hook up a car subwoofer to a home stereo directly if:

  • You have a subwoofer or more than one subwoofer that can be wired for at least 8 ohms total. This can be two 4 ohm subwoofers or a 4 ohm dual voice coil (DVC) subwoofer.  [See diagrams below for how] 
  • Your home stereo or amp can handle 4 ohm speakers (most can’t so let’s ignore this).
  • Using workarounds: this includes using a small 4-ohm capable amp between the receiver and sub or an inline resistor to bring up the speaker load. (Don’t worry – I’ll share these in detail below)

Even if you have the right car subwoofer(s) your amp needs to have enough power available to drive the subwoofer box. The good news is that for casual listening you don’t need a ton of power like you do for cars and truck use.

The single biggest obstacle is that most home stereos, home theater receivers, and home amplifiers can’t handle the 4 ohm speaker load of many car subwoofers. It’s 2x lower than the 8 Ohm minimum most require. (Some car subwoofers are even 2 ohms, in fact).

Why can’t I use a 4 or 2 ohm car subwoofer with a home stereo?

Diagram showing how to match speaker ohms to a home stereo

You’ll need to be sure to avoid connecting a speaker impedance (Ohms, speaker load) that’s too low to a home stereo amp or receiver. Doing so causes it to try to produce more electrical current than it’s designed for. This causes overheating and potentially permanent damage to your electronics.

Just like car amplifiers & car stereos, home stereos have a minimum speaker load, stated in Ohms, that they’re designed to handle. 

Never try connecting 2 or 4 ohm car subwoofers or speakers to a home stereo – they’re likely to overheat very quickly and suffer possible damage.

Why is matching speaker impedance important?

Matching the speaker load to your home stereo just means matching it up with the best Ohm load that will deliver the power & volume it’s designed to produce. As you can see in my diagram above, if the speaker is over the rated Ohm spec, it will work safely but at the expense of delivering a lot less power and volume than you’d like.

Using the correct Ohm load means you’ll get the rated power – and as you might guess – the maximum volume possible. 

However, using less than the rated Ohm speaker load (whether 1 or more speakers, the total Ohm load the stereo sees) is dangerous and won’t work. Don’t do it!

Tip: In cases where the subwoofer is less than 8 ohms total and/or the receiver or amp doesn’t have enough power don’t give up! There are some work-arounds that can you can use as we’ll see.

Do I need a speaker crossover for a car subwoofer?

Example of a passive subwoofer low pass crossover

Example of an 8-Ohm compatible low-pass speaker crossover for blocking all sounds above a low bass frequency (cutoff frequency). These are used to get “clean” sounding bass from a subwoofer when there’s no crossover already provided.

By the way, there’s another important part you’re likely to need and may not have thought about: using a speaker crossover for clear bass with a car subwoofer. Car subwoofers are normally used with a car amp with a low-pass crossover built in already.

That’s often not the case for home stereos, although some do have a subwoofer RCA output jack for use with an amplifier or powered subwoofer.

Diagram showing a passive subwoofer speaker crossover

The point is that unless you want to hear vocals and other sounds from the car subwoofer, you’ll need to hook up a subwoofer speaker crossover between the stereo & the sub. For clear bass, you’ll need a crossover to block higher-frequency sounds subs can’t play well.

If you’re lucky enough to own a receiver or home amp with a low-pass crossover built in you can use that instead.

How to wire a car subwoofer to a home stereo

How to connect a car subwoofer to home stereo diagram

As you can see from my diagram above, I’ve come up with 4 ways to connect a car stereo to your home stereo receiver or amp – but it greatly depends on the specifics. For example, using a 4 ohm car sub is relatively simple, while using a 2 ohm or another type can be more complicated.

Here are the  4 ways you can do this:

  1. Two 4 ohm car subwoofers: This is one of the simplest setups possible. Just connect the subs in series for a total of 8 ohms and connect them to one of the stereo receiver speaker outputs. However, be aware that if there’s no speaker crossover in place or built-in, you’ll get vocals and sounds in the subs that won’t sound good, so a crossover may be needed. (see above)
  2. Single DVC 4 ohm subwoofer: Likewise, a single dual voice coil (DVC) subwoofer with 4 ohm windings can be wired in series to meet the 8 ohm requirement. Just like above, a low-pass (subwoofer) crossover may be needed.
  3. Single 4 ohm subwoofer or receivers without enough power – using a mini amp: You can use an affordable miniature amp to drive a 4 ohm car sub directly, avoiding the needed to lose power like you would in option #4. You can use a mini amp that can drive a 4 ohm or even 2 ohm car sub directly. Some also have a built-in crossover for great sound making them a great choice.
  4. Single 4 ohm subwoofer using a series power resistor: This is the simplest and most affordable option. Using a power resistor (a resistor that’s designed to handle higher power levels) just wire it in series with the sub to get the 8 ohms needed. Power resistors can be found for around $5 more or less. I recommend a 25 watt or higher rating, depending on your stereo’s power output.

Note that while option #4 is the easiest of all, I don’t recommend it because you’ll lose 1/2 or more of the stereo’s power output. That’s because the power is divided between it and the sub. 

Audio power resistor examples

Examples of power resistors you can use for speaker projects including hooking up a sub to a home stereo. These resistors can be found and electronic parts stores and speaker part retailers, or even Amazon or eBay. They’re often priced very affordably (around $5 or so for a pair or pack).

What to do if you can’t get the right Ohms together

Home stereo mini amp example

Example of a small & affordable amplifier that can be used to drive a lower impedance car subwoofer from your home stereo receiver. You can find these with a crossover built-in (as shown here) for under $30.

It’s a bit tricky in some cases – especially when using multiple car subwoofers and/or those like 2 ohm models, for example. A home stereo amp is a great answer to this problem and offers several benefits:

  • Can drive lower impedance subs directly
  • Low cost (often under $30) and very compact size
  • Some include a low pass crossover built in meaning you’ll save a lot of hassle

While I realize you might not want to have to spend money & wait for the stuff to arrive, it’s definitely worth thinking about. Here’s a good example of an inexpensive one I found.

How do you hook up a subwoofer to a receiver without sub output?

Image showing examples of line level RCA converters

Examples of line level converters use you can use to get an RCA low-level signal from a home stereo without subwoofer RCA outputs.

The good news that if you’re planning to use a small amp to power a sub at home but your receiver doesn’t have a subwoofer or other RCA outputs there’s a solution. You can use a line level converter, commonly used for factory-installed car stereos, to create some, then connect to a subwoofer amp.

You’ll want a good quality one with adjustable output level dials to be sure you don’t have problems with the signal level. They’re especially valuable to have as many vintage or older home stereos don’t have subwoofer outputs.

You can connect them just like you would a speaker, either to unused speaker outputs or also connect them alongside speakers already in use.

How many watts do you need for a subwoofer?

Man thinking about how much power for car subwoofer with home stereo

Car subwoofers are very inefficient speakers and are some of the most power-hungry you can find! The good news is that if you’re just looking forward to average listening levels you can get by with less power.

  • For easy listening, low-volume music levels, or sound from movies, you’d want at least 25 watts RMS of power per channel available to drive a subwoofer.
  • For a bit more “punch” that requires extra bass (especially the bass & thuds from DVD or BlueRay video sound) 50W+ would be much better.

If your home receiver is on the weaker side as some budget models are (for example, 15W-20W per channel) you’ll need a small external amp as I mentioned earlier. If you’re planning driving a car subwoofer with high volume and want some serious bass I’d recommend a minimum of 100W RMS and even more if you can afford it.

Bookshelf stereos usually can’t cut it – they’re just not designed to produce much power. However many decent quality home stereo receivers or home theater amps/decoders can do the job ok.

Home stereos vs car amplifiers

On the downside, home stereos don’t produce anywhere near the power of today’s car amps which typically have at least 75W to 100W or more per channel, if not several times that! On the plus side, when using a subwoofer inside your home you don’t have the terrible acoustical losses that you do in a car or truck.

This means when using a car subwoofer inside your home you need less power to hear it well.

Subwoofer sensitivity (efficiency) & volume

Some subwoofers produce more volume for the same amount of power. This is actually a standard specification used to compare speakers and the official name is speaker sensitivity. In other words, the sensitivity of a speaker describes the volume output it produces for a given amount of power, in decibels (dB).

A standard dB reading of 1 watt measured 1 meter (1M) away is used for this measurement in the speaker industry.

When comparing two subwoofers, for example, one might have a sensitivity of 87dB/W while a 2nd one has one of 91dB/W. This means the second produces more sound with less power. Because speakers require a doubling of power to increase another 3dB in volume, that means a more efficient speaker can use 1/2 the power or less than another speaker for the same volume!

That’s something to think about when comparing subs.

Will a sub work without an amp?

can you use a sub without an amplifier question man thinking

This one’s easy to answer, although it’s important to be clear about power & amplifiers. In general terms, no, a sub won’t work ok without an amp.

Hang on a second, though! What does “amp” mean in that case? To be more clear, here’s the long and short of it:

  • A subwoofer, like any other speaker, must be powered by an amplified audio signal with a decent amount of wattage in order to produce sound.
  • To properly drive a subwoofer for it to work well, that’s different; in that case, yes, without question you need an amplifier of sufficient power to drive it well.

That is to say, you can’t hook up a subwoofer to a non-amplified signal output from any stereo or other audio source. You need an amplified speaker output with a fair amount of power in order for it to work ok and sound right.

As I mentioned earlier, for casual listening inside your home you can likely get away with 25 watts for subwoofers with decent efficiency. However, if you want to drive a subwoofer hard and get that real bass “thump”, you’ll need a lot more power: 80-100W or more for a home amplifier.

More great articles about speakers and audio

Don’t miss out – there’s a lot more great reading ahead! Check out some of my other detailed articles:

Got questions or comments? Feel free to leave a comment below!

How To Connect A Subwoofer To An Old Amplifier Or Vintage Receiver

How to connect a subwoofer to old amplifier or vintage receiver featured image

Got a vintage amplifier or receiver? When it comes time to add some great low-end bass you might be scratching your head wondering how – and if – you can add a subwoofer. 

The great news is that there are several ways to connect a subwoofer to an old amplifier or vintage receiver.

Even better, it won’t cost a lot, either! Read on and I’ll share with you 3 ways to connect a subwoofer along with clear subwoofer diagrams anyone can understand.

Contents

Home stereo subwoofers explained

Passive vs active home subwoofers diagram

Comparing passive (non-powered) vs active (powered) home stereo subwoofers. Powered subwoofers have an internal amplifier and one or more signal input options: speaker inputs, RCA input(s), and in some cases, digital audio inputs.

There are two kinds of home stereo subwoofers: powered (“active”) and non-powered (“passive”).

  • Powered subwoofers use a low-signal signal which is boosted greatly using the built-in speaker amplifier, power supply, and crossover. These types are one of the most common and in many cases use an RCA type input jack to connect to the receiver for sound.
  • Passive (non-powered) subwoofers are simply a subwoofer speaker inside the bass enclosure which is directly wired to the speaker terminals or a passive bass crossover inside. These types are less common.

How does a subwoofer work?

An amplifier boosts the low-level input signal in order to drive the subwoofer’s voice coil with sufficient power and move the speaker cone, producing sound. As the cone moves the air inside of a specially designed enclosure (speaker box) deep bass, contained in the musical input signal, is produced.

They’re designed for only low-end bass and not voice or other musical instrument frequencies.

A powered subwoofer includes an amplifier already inside the subwoofer enclosure. It also has a built-in low-pass crossover to block higher sound frequencies in order to produce clear and great-sounding bass only.

For non-powered subwoofers the problem comes when you connect one to an amplifier or receiver’s outputs without a crossover – it sounds terrible!

Old amplifiers and vintage receivers vs new receivers

Unlike older amplifiers, more modern home stereos and especially home theater receivers have a subwoofer output jack (or pair of jacks) dedicated to this bass signal a subwoofer uses to create sound. This is usually from stereo music signals or the subwoofer (“.1”) channel sound in multi-channel surround sound material such as Dolby Digital or DTS.

For example, you may see terms like “5.1” or “2.1” speaker systems or surround sound audio listed for movies. In this case, the first number represents the number of main speakers. The “.1” is used to represent a sound channel limited to only bass for subwoofer use.

Older amplifiers and receivers don’t provide a subwoofer output so we’ll need to connect a subwoofer using some other ideas.

Powered subwoofer inputs & controls to know

Powered subwoofer example with inputs and controls labeled

Shown is an example of a powered subwoofer’s rear panel with 2 kinds of inputs: speaker inputs and RCA (low level) input jacks. Note that not all subwoofers offer speaker level inputs, meaning if yours doesn’t have them it’s a bit harder to connect the bass signal input.

Powered subwoofers usually have a few different inputs and controls. It always depends on the particular brand and model you buy.

Here’s what you’ll usually find on most:

  • Power input (AC outlet power)
  • On/off switch
  • RCA input jack or a pair of jacks
  • Subwoofer crossover adjustment
  • Subwoofer level adjustment know (the amplifier’s signal boost level)

In most cases, a subwoofer input jack, if you had one on a receiver, is a “mono” (monaural, 2 stereo channels combined into one) signal you connect with a single RCA cable.

Receiver subwoofer output jack example

Shown: What a receiver with a subwoofer output jack looks like as found on many newer receivers. These connect to the RCA input jack on the subwoofer, if present.

Of course, if you’re reading this it’s because you don’t have a receiver with a subwoofer output. In fact, some of the information you’ll find right now on the internet says that you have to buy another subwoofer if you don’t have a receiver with an output jack. That’s simply not true.

Subwoofers with speaker level inputs are great to have for exactly this reason as you can connect them directly to an older amplifier or vintage receiver’s speaker outputs.

Even if you buy (or already own) a subwoofer without speaker level inputs, it’s ok – there’s another way to basically connect it essentially the same way!

Below you’ll find a diagram showing how to connect an old amplifier or receiver without a subwoofer output easily.

Diagram & examples: Connecting a subwoofer to an old amplifier or vintage receiver

Diagram showing how to connect a subwoofer to an old amplifier or vintage receiver

1. Connecting an old amplifier or receiver to a subwoofer with RCA input jacks

Example of a powered subwoofer RCA jacks & RCA Y adapter cable

Left: Example of a powered subwoofer with 2, instead of the typical 1, RCA input jacks. Right: An RCA Y adapter that can be used with a line level converter to connect to a subwoofer with a single RCA input jack.

If you’ve got a subwoofer with 1 or 2 RCA input jacks and no speaker level inputs, here’s a simple and high-quality way to connect it: by using a line level converter.

What is a line level converter and how do they work?

Line level converters (also called RCA speaker level adapters) are small electronic devices that connect to speaker outputs from an amp or receiver and scale down the higher-voltage signal to a low level (“line level”). The outputs are RCA jacks which can then be connected to any amplifier or subwoofer with RCA jacks.

 While you almost never see them used for home stereo systems, they’re extremely handy in the car stereo world because they make it possible to connect a stereo without RCA outputs to any amplifier or powered subwoofer.

Likewise, they can be used for home stereo amps and receivers, too!

Image showing examples of line level RCA converters

Shown here are two examples of line level/RCA speaker level converters that work well for home receiver/amp to subwoofer use.

How much do line level converters cost?

Line level converters vary in price a bit depending on the quality and features, selling around $15-$25 or so in many retail stores and online stores.

How to use a line level converter

To convert speaker level outputs from your amplifier or receiver to RCA jack subwoofer outputs, you’ll connect the provided speaker wire connections (marked by colors and striped) just like you would regular speakers. You then connect RCA cables (or a single cable, depending on your particular one) to your powered subwoofer.

The internal electronics not only scale down the speaker output voltage from a receiver but also help prevent noise from the audio path, too. Most, but not all, speaker level adapters do not need a power source.

If your subwoofer has a single RCA subwoofer input jack, you may want to pick up a “Y” RCA adapter to combine both receiver channels on the output side into a single mono RCA plug.

Subwoofers with 2 (stereo) RCA jack inputs will need a standard stereo male-male RCA cable.

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2. Connecting a subwoofer with speaker level inputs

Example of subwoofer speaker level inputs

A subwoofer with speaker-level inputs is especially easy to connect to your older amplifier or receiver! To do so, just connect to the speaker outputs on the source unit using speaker wire and then to the matching inputs on the subwoofer. You can even power speakers from the amp or receiver at the same time.

If your subwoofer has speaker level inputs built-in you’re in great shape! Just connect them directly to your amplifier or receiver’s speaker outputs, either to unused speaker terminals or at the same time (in parallel) with speakers connected to the receiver.

Just like an off-the-shelf line level RCA converter I mentioned earlier, the subwoofer’s internal electronics will scale down the speaker signals to a much lower line level signal the internal amp can use.

You can still expect very nice sound quality as the signal used is just divided down and isn’t changed. Because speaker level inputs have a very high input impedance (total input resistance), in most cases it won’t hurt to connect them to your receiver or amp at the same speaker wire terminals where speakers are already connected.

To do so, you’ll just connect them in parallel: positive speaker inputs to positive speaker outputs and negative speaker inputs to negative speaker outputs.

Additionally, there’s a low-pass crossover built-in as well to produce great-sounding bass and no unpleasant parts of the music – just pure, low-end bass.

Note: Subwoofers with speaker level inputs and outputs provide a way to easily connect both at the same time. The outputs are internally connected to the input connectors, making it easier to add speakers and the subwoofer to a receiver simultaneously.

3. Connecting an amplifier’s speaker outputs to a passive (non-powered) subwoofer

Example of a passive subwoofer low pass crossover

A passive subwoofer low-pass crossover, unlike an electronic crossover, works using capacitors and inductor coils instead of electronic components to filter out the unwanted higher-frequency sound that would otherwise go to the subwoofer. This lets you power the subwoofer with only a lower bass sound similar to how a powered subwoofer works.

Using a passive (non-powered) subwoofer is definitely not as easy as a powered one. The good news is that it can be done, and relatively easily, too. In fact, it you don’t have to worry about going broke, either, although you will need to do a bit of shopping.

To connect your amplifier or receiver to a non-powered subwoofer as is shown in the diagram above, you’ll need to pick up a low pass crossover that you’ll connect between the amp or receiver and the subwoofer.

These will filter out sounds above the crossover frequency and provide only a nice bass sound to it.

How to choose a subwoofer crossover

Speaker crossovers like the one shown are sold both in a single (one speaker) or dual (2-speaker) models depending on the brand & supplier. They also have to be matched correctly to the impedance (Ohms rating) of the sub.

For example, for an 8 ohm subwoofer, you’ll need to use a crossover designed for 8 ohm speakers. Otherwise, the sound filtering is radically different and won’t sound right since the speaker load will change how the crossover filters the sound quite a lot.

Normally you’d choose one with a low-pass frequency of close to 100Hz or close to that. You may need to shop around to do so.

Where to shop for passive subwoofer crossovers

Speaker crossovers are sold where speaker parts & related components are sold as well as marketplaces like Amazon or Parts Express. Other speaker specialty stores where replacement speaker parts are sold may have them, too.

Stereo vs surround sound receiver subwoofer output comparison

Stereo vs surround sound receiver differences diagram

Unlike older or standard stereo receivers, surround sound receivers have a unique output that comes from the surround sound movie or music source. However, in regular stereo listening mode, they act the same as regular receivers.

Just as a side note, one thing to be aware of is that when you connect a subwoofer to an old amplifier or receiver you won’t be able to get the separate dedicated bass sound channel (.1 channel) like you can with a surround sound receiver. 

Those are able to extract the dedicated bass sound from a DVD or other media and route it to the subwoofer output jack. On the other hand, it might not even be a problem.

Did you know? The surround sound receiver “LFE” (low-frequency) output is considered optional – hence the “.1” name. 

Surround sound receivers and amplifiers are designed so that you can play nearly all the sound through the main speakers if needed.

In some cases, for example, some movies and music use the bass channel to really draw you into the experience. Using a receiver without that output means you can’t get the same effect, but that’s only for surround sound mode.

The good news is that in stereo mode, both new and old receivers & amps have very similar subwoofer behavior when connected as you’ve seen here. In other words, you probably won’t really miss it if you’re using an older receiver or amp.

That’s just something to be aware of in case you’ve considered upgrading at some point.

More articles with speakers, speaker wiring, and diagrams to help

I’ve got some other great info to help you learn more and get your system going:

Questions, comments, or etc?

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