car tweeter diagrams

How To Install And Wire Car Speaker Crossovers The Right Way

November 13, 2020

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 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?

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.

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

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:

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!).
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.

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

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:

Low-cost 6dB/octave crossover (capacitor) mounted right on the tweeter.
A single capacitor wired inline on one wire.
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?

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.

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

November 9, 2020

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

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:

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).
“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.
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 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:

High up near the level of your ears
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 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

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:

Strip the speaker wire and prepare it for the connector
Insert firmly into the (correct size) crimp connector
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

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:

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.
Hold the tool & pressure in place firmly so it cannot move.
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.

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

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:

Strip the wire leaving 3/8″ to 1/2″ bare wire exposed.
Tightly twist the wire so it can be pushed into the connector properly.
Insert the wire into one end firmly, pushing it into the metal contact inside. Be sure to insert it fully.
Place the connector into the crimp tool in the appropriate position in the tool, near the end of the connector.
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.
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?

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?

Here’s the short answer:

You cannot use tweeters on a monoblock (bass-only) amp or a subwoofer output channel using a low-pass crossover.
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?

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

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:

Are you tweeters too loud? Find out here how to reduce tweeter volume with resistors.
Find out here everything you could want to know about tweeters.
Confused about tweeter, midrange, or woofers crossover frequencies? Here are the best crossover frequencies for home and car audio.
What happens if you change your tweeter impedance? Find out what happens if you change the speaker impedance with a crossover.

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!