How-to guide

How To Install A Subwoofer And Subwoofer Amp In Your Car – The Complete Guide With Diagrams

Installing a subwoofer in your car yourself feels great! It’s so much fun to finally enjoy the awesome bass you’ve been missing in your music. There’s nothing like learning to do it on your own and being able to show of what you’ve done and feeling the pride that comes with a job well done.

I’ve seen a lot over the years as I’ve done hundreds of car audio installations – and unfortunately I saw a lot of good people end up with a terrible sounding system or heard about them getting ripped off. I don’t want that to happen to you.

I’ve put together an extensive guide to help you get started and give you lots of buying information, diagrams, installation steps, and a general understanding of the details you need to know.

Hopefully my guide will help you enjoy a job well-done and cut costs, too.

Table of contents


Infographic – How to install a subwoofer in your car

Infographic for how to install a subwoofer in your car


Before you get started – things to prepare for

In order to help you understand the big picture I’ll explain the basic things we need for great sound and a successful installation:

● Electrical connections:

  • +12V battery connection with a fuse
  • A good, solid connection to the car’s metal body
  • +12V “remote on” lead to turn the amplifier on or off with the stereo or ignition
  • An audio signal source to provide a signal for the amplifier to boost
  • Wiring from the amp to the subwoofer

● Subwoofer details:

  • A speaker made for producing heavy bass (subwoofer)
  • An enclosure designed for bass to install the subwoofer in (or a preassembled subwoofer box)

In most vehicles, a +12V connection at the battery is relatively easy to find and route power wire to the amplifier mounting locatio you’ve chosen. However, in today’s vehicles finding a +12V wire for the remote on connection that turns on and off with the factory stereo or the ignition switch (normally the accessory position) can be harder. This is because today’s vehicles have more wiring which is related to computerized signals and don’t use 12V. They’re often a much lower voltage or are a data signal bus and cannot be used for this purpose.

quick tip
There’s less time and frustration if you get the right parts and tools the first time rather than having to do so after you’ve already started. Try to get the basics you need first before starting.

I’ll cover all of this below.

● Planning time

Installing a subwoofer in your car can be hard work depending on the vehicle and what you’ll need to go through for installing and hiding the wire. If you’re adding a subwoofer to a factory system you should definitely prepare for additional work. A good estimate is perhaps 3 hours or more for adding a subwoofer to an aftermarket stereo and 4.5+ hours for a factory system.

Image of a young man working on car in garage

Try to allow enough time for daylight and to avoid rushing your work, especially if it’s your first time doing your own car audio installation. If you get stressed because of time you’re more likely to make mistakes and have to redo something later. Better to plan well or stop and pick back up the next day. If you can however, borrowing the use of a friend’s or the family’s garage is a huge help.

The right tools make all the difference! It’s worth it to wait a bit and get all the right tools together rather than struggle with the wrong ones. You don’t have to spend a lot of money, but if you’re a careful shopper you can usually get most of what you need without going broke. Most of them are basic tools and cheap ones can be found or you can get a decent tool set for a great price than includes most of them you’ll need and I’ll list in this guide.

I’ll list what you need based on my many years of experience installing car audio in the next section.

Getting the right equipment and parts

This is one of the single best steps and without a doubt, buying the right amplifier and subwoofer box & speaker are critical for good bass sound. The good news is that you have more options than ever today!

● Parts to gather before you begin

  • Amplifier wiring kit (see notes below) with fuse holder, remote wire, and connection accessories
  • Speaker wire for subwoofer (and also signal if using factory stereo)
  • Hand tools
  • Mounting brackets for mounting down the subwoofer box if needed
  • Cordless variable speed drill – not required but highly recommended
  • Good quality electrical tape (should say “UL Rated” on the inner roll)
  • Wire (zip) ties, small bag – 6″ or 8″ are great but others work well
  • Small package of 3/8″ length #8 self-tapping screws (if you have a drill)
  • Wire metal coat hanger (great for bending into a straight piece for pulling wire)

I’m a big fan of the Black & Decker cordless drills and they’ve done very well for me for installation jobs. Here’s the one I’m using now and I recommend it for you too.

You might also consider planning ahead to upgrade your speakers to some better sounding ones while you’ve got your vehicle already apart, too.

Amp wiring kits

Amplifier wiring kits come in a variety of qualities and a variety of variations of what’s included with them. Some only contain a fuse holder, fuse, power wire, ground wire, and the remote lead wire (typically an 18 gauge wire). Others also include RCA cables and speaker wire. The best kits include installation accessories like ring terminals, zip ties, and sometimes wiring grommets.

I definitely recommend purchasing a kit that is complete. For the average amplifier you don’t need to spend a huge amount of money for a good kit. Close to $30 can get you a great 8 gauge wire kit that’s well made and includes everything you need.

Image of a subwoofer installation wiring kitA good amplifier wiring kit can be bought with nearly everything you need for a great price: fuse, fuseholder, subwoofer speaker wire, power cables, remote on wire, zip ties, RCA cables, ring terminals (for battery and ground), and a few other bits and pieces. You can find some great ones on eBay and Amazon (but I recommend Amazon so you can check reviews, as eBay sellers often will sell you bad quality kits!)

Note: Not all wiring is the same. Some misrepresent the wire they contain and don’t actually contain pure copper wire or contain wire that is actually smaller than advertised (but looks larger because of the wiring jacket). Be sure to check reviews before buying.

Here’s a great write up I’ve made as well as several great kits I recommend.

Speaker wire

For an average subwoofer or pair of subwoofers, a small section of 16 or 14 gauge can work well. You can find 25 ft lengths or smaller for a good price. You don’t super-expensive brands, so don’t get talked into spending a lot of money. Just try to find a quality wire that’s reasonable in price on a roll.

Heads up! Speaker and power wire marked as “CCA” is not pure copper wire! Because of the rising cost of copper, manufacturers are now using copper coated aluminum wire, which is lesser quality than pure copper wire (and less expensive). For your speaker wire, it’s likely fine, but be aware when shopping. Sometimes the CCA note is in small print!

wire of 16 ga speaker wire

Don’t waste money on overpriced speaker wire. The main thing to remember is to buy quality wire – preferably a name brand type – with good insulation and good conductors. One wire should be marked so that you can refer to it as the positive lead.

When connecting to a factory system with no RCA jacks, expect to also pick up a roll of small gauge wire (18 or 20 gauge is good) of sufficient length to go from the vehicle’s speaker wiring to the amplifier. A 50 ft roll should work well for 2 pairs of speaker wire being run.

Here’s a good choice that’s cost effective and is good quality.

● Amp selection

This is very important but the great news is that these days most amps have the basic necessities for working with a subwoofer enclosure and producing good bass.

When choosing an amplifier, look for these basic features. Remember that you can use both a single-channel (also called “mono block”) amplifier or multi-channel amp that can be bridged for more power.

Features you need for good bass are:

  • 150W RMS power for the subwoofer available (either a single amp channel or 2 bridged channels)
  • Low-pass crossover for passing only clean bass and no upper-range music
  • A mid to high-quality brand with good reviews
  • Speaker level inputs option (if using a factory stereo)

Bridging an amplifier means wiring the speaker connection so that we take advantage of a built-in design feature which allows 2 amplifier channels to drive one speaker (or pair of speakers) for more power. This typically allows 4 x the power of a single channel to be provided! (Always check the specifications to be sure of power available and the required speaker Ohms rating).

For the average person, an amplifier capable of producing 150W for use with a well-matched subwoofer and speaker is adequate. If you want real “thump” and heavy-hitting, loud bass, plan to spend more and get a model with more power.

Close up image of a car amp crossover controlsToday’s car amplifiers normally provide high or low-pass crossovers to block bass or to block upper-range music from being played depending on the speakers used. This amp shown has adjustments for the range of sounds that can be played when the crossovers are used (which are optional). The “Full” setting means all sounds are passed to the connected speakers.

A low-pass crossover is a feature which will actually filter out upper-range sounds and will allow you to play only low-frequency, clean sounding audio. Most car amps sold today offer this. Some also have additional features like an adjustable crossover frequency (as opposed to a simple on/off switch, with a fixed frequency) and a bass boost feature. These features are a requirement but can help you tailor your system’s sound more if needed.

Regarding power, you can likely get buy with less if using a small subwoofer (for example: an 8″ or other small type of subwoofer in a premade enclosure). For noticeably louder and better subwoofers, however, it’s best to follow the rule above as a general rule for the average person.

On average, expect to pay near $100 for decent quality amplifier. However, today for around $150 you can get a better brand with great sound and excellent user reviews so you can be confident you’re making the right choice. After all, I’d rather you are happy and don’t make a mistake!

In my opinion, and after years of dealing with customers and various types of car amps, I strongly advise spending just a little bit more money to get something better rather than getting the cheapest amplifier you can. It’s a better plan in the long run and they are more reliable, too.

Using multi-channel amps vs. single-channel (mono) amps

If you plan to power additional speakers in the future and expand your stereo system, think about buying a 4-channel stereo. Even if you don’t use all 4 channel at the present that’s fine – you can always use them later, leaving 2 channels to power front speakers and bridge the 2 rear

Both types of amplifiers have their pros and cons to consider.

Multi-channel amp (4 channel, for example):

PROS:
  • Flexible and great for multiple speaker systems
  • Lots of brand and models available
  • Can be used in 2, 4, and other channel modes (bridged)
  • Popular, so often many reviews are available

CONS:
  • Tend to have lower power ratings
  • More power connections to deal with
  • May not be as compact as a mono amp

Mono (single channel) amp:

PROS:
  • Not flexible – useful only for subwoofers in most cases
  • Selection and options tend to be more limited
  • Many are low-pass only, no full range possible

CONS:
  • High higher power available for subwoofer use
  • Often can be as compact as or smaller than multi-channel amps
  • Simpler controls in many cases

I recommend you buy a good quality 4-channel amp with 50W x 4 or 75W x 4 (at 4 ohms) that is bridgeable to 150W or more. You’ll have more flexibility for in the future and won’t have to buy another amplifier. It’s the best bet for the beginner and the average person in my opinion. It’s always smart to plan ahead.

There are some excellent choices available today including a wonderul amp I reviewed here as well!

● Subwoofer selection and things to know

If you’re buying your electronics and subwoofer for the first time, it’s best generally to avoid buying an enclosure and subwoofer separately unless you know the recommended enclosure volume size (in cubic feet) for the subwoofer speaker or speaker pair. Also, I recommend you buy a sealed enclosure as mismatching a subwoofer with the wrong vented box can result in terrible sound!

I witnessed this many times, and it’s incredibly disappointing to see.

I’ve done many speaker designs of various types, and here’s a simple explanation of why it matters: Every speaker has certain parameters that determine how it performs in certain types and sizes of speaker boxes. If the speaker is not matched correctly, the sound produced can be far below what it should be able to produce.

This can result in “bottoming out” early (the speaker has little resistance to movement and begins to reach its limits when moving) or simply can’t produce bass sounds at a normal volume. Your hard work will have been for nothing if that’s the case, and it feels terrible to work very hard only to get bad sound. Trust me, I know, and I’ve helped many people in the past resolve it.

Image of MTX subwoofers in an enclosure Image of MTX subwoofers in an enclosure

 

It’s best to start with a subwoofer combo in which 1 or 2 subwoofers are correctly matched to the box they’re in. In most cases a brand name box with speakers is designed specifically to work well with the speakers based on their particular characteristics. And the resulting sound is usually great! This is the most convenient option for some people. 

My advice is buy a brand name pre-assembled (“preloaded”) or matched subwoofer speaker/box combo. It will pretty much guarantee you’ll get good sound. If buying a preassembled box, you can’t also buy a vented (ported) model if you wish.

Ported speaker boxes generally have slightly less “tight” sound but can often play louder and deeper vs. a sealed box for the same amount of power. So it’s generally your preference. Many small subwoofer combos are ported to get more sound from a small size.

Generally speaking, you’ll need to buy 4 Ohm subwoofers

Many amps, both single channel or bridged multi-channel amps, require a minimum speaker impedance (Ohm rating) of 4 Ohms, so bear this in mind when shopping. You can learn more about that here.

Consider buying a car powered subwoofer instead

A car powered subwoofer is one that is an all-in-one bass system made up of a special enclosure, matching subwoofer, and has an amplifier already built-in. They’re easier to install than a separate amplifier/subwoofer system.

Additionally, they’re a great choice for people who may later change vehicles especially people who own leased cars. The total cost for a power subwoofer vs. separate items may be lower, too!

Image of MTX AUDIO RTP8A powered subwoofer side view

A powered subwoofer is an all-in-one solution for subwoofer bass. Although many are extremely compact in order to fit in particularly space-limited vehicles, some like this one provide bass nearly as good or as good as a standard amp + speaker box installation. Typically their overall cost is less or the same as buying the items separately. There’s also no amp to worry about mounting, too!

They do have drawbacks, however: while they offer a more convenient way to install and remove the audio system, they tend to be more likely to have lesser performance than by using a standard amp and box system. Car powered subwoofers tend to be more oriented to solving the problem of limited space in a vehicle and therefore may be more limited in their speaker size, amplifier power rating, and the bass volume they can produce.

Note that they’re generally great choices if you want good but not extremely loud bass in your vehicles. Some models, however, feature larger speakers and high power built-in. I’ve covered this topic and show some great examples here.

Pro Tip
Whenever possible, if buying a powered subwoofer, get the largest model you can fit into the space you have available. Under-seat and other ultra-compact models produce some bass that adds a good extension to your music, but there’s no substitute for true air displacement like from larger subwoofers. The best sound generally comes from larger speakers like 8″, 10″, and 12″ speakers for example.

Get the right tools together

I’d consider the following tools essential:

  1. Phillips & flat head screwdrivers
  2. Good & inexpensive wire cutting pliers
  3. Needle nose pliers
  4. Utility knife with retractable razor blade
  5. Miniature flat head screwdriver or other similar tool(s) to pry apart plastic trim panels and adjust the amplifier gain at the end

Ideally you’ll have access to these as well, although I realize sometimes they can cost more than they should:

  1. Digital multimeter (test meter) for measuring voltages
  2. Cordless variable speed drill with clutch (absolutely FANTASTIC for speeding up work, drilling holes, and driving screws!)
  3. Crimp tool & crimp connectors
  4. Wire stripper (not a requirement but greatly simplifies work effort)

Some of these can be bought at stores like Wal-Mart or Harbor Freight for a discount price. However, it’s hit-or-miss whether or not they carry all the items you need. Most can be bought for cheap on eBay or Amazon.com.

I’ve been very happy with my digital multimeter from Harbor Freight. It was a great deal, and has lasted well! (Note: they also carry a cheap $3-5 budget version that will work also for installation troubleshooting).

Crimp tool with crimp caps

Image of blue butt connector

A crimp tool (shown with crimp caps) is a great tool for a professional-quality installation to avoid having issues with wire connections later. I recommend blue butt connectors (right) as they’re a bit easier to use and fit 16-14 ga. wire but can also be used with smaller gauge wire if you fold it underneath itself before inserting.

 

Getting the subwoofer ready

If you’re following my recommendation for buying a preloaded subwoofer box, then the work should be done for the subwoofer itself. If you purchase an enclosure and subwoofers separately, you’ll need to install them securely.

image of drywall screw Image of subwoofer being mounted in box

Install the subwoofer in the box. I highly recommend using a cordless drill and drywall screws as they go quickly into the wood material of the box. Most subwoofers use 8 screws. Don’t skimp on this! Subwoofers are heavy and have a lot of vibration when in use. It’s best to ensure they’re securely fastened.

If the cordless drill has a clutch set it to one of the first or lowest acceptable settings to ensure you don’t strip out the box material when fastening down the speaker.

Installing the amplifier & subwoofer

Here’s a general diagram to help you visualize the installation:  (Click to enlarge or click here to get the .pdf you can view or print)

How to install subwoofer and car amplifier infographic diagram● Installing an amplifier consists of several basic steps:

Route the positive wire cable to the car battery and hide it underneath the carpet and interior trim on the battery side of the vehicle.

In order to do so, you’ll need to pull up some of the interior plastic trim like rocker panel covers which usually snap off and snap back into place. Always be careful, and if necessary, carefully use a flat head screwdriver between gaps to help pry them off. Pull back the carpet to find room to hide your amp wire.

Door sill trim removal pic

You can then find the edge of the carpet which is usually easy to pull back and tuck wire into.

Running wire to the car engine and battery

Honestly, getting the wire to the battery is usually the toughest part you’ll face. But don’t worry, there’s nearly always a gap, hole, plug you can remove, or a rubber wiring harness seal you make a hole in by pushing a screwdriver or similar tool through.

With a flashlight, look underneath the dashboard and try to find a plastic filler plug that can be pushed out (exposing a free hole you can use) or a rubber seal with a factory wiring harness that goes into the engine compartment. If you need to do this, use a punch, pointed object, or even a very strong and long screwdriver to put a hole in the rubber seal. Then use the “coat hanger trick” to act as a wire snake for help pulling the wire through.

Image of positive amp wire pushed through firewall grommet

If possible, push a hole through a firewall wiring harness seal (“grommet”) and push the amp wire through that.

Image of car engine firewall plug

If by chance you find a plastic hole plug like this pop it out using a screwdriver and use it as ready-made power cable hole. That makes things MUCH easier!

Image of engine compartment wiring harness rubber seal amp wire install

If you’re going through a factory wiring harness seal as pictured in the 1st pic, push it through until you can grab the wire and then from there pull it through the engine compartment. Then you’re past the hardest part!

The coat hanger trick

With some pliers you can straighten out a standard coat hanger in order to create a “wire snake” which is a tool used to pull wire through small spaces. After doing so, you can wrap electrical tape around the power wire and attach it to the end. Then push it through the car interior (if no easier alternative is available) and into the engine compartment, where you can then finally pull it through by hand and remove the power wire from it.

It’s best to bend the ends so that they’re rounded and won’t snap easily on obstacles in the way. For best results, make a small loop on the end where you want to attach your wire and wrap it well with electrical tape to smooth over sharp edges that may snag.

Image of straightened coat hanger

A useful trick is to use a coat hanger to make a “wire snake” to pull wire through tight and difficult areas, especially when going from the interior into the engine compartment.

Running the wire the to back of the car

You may find it easier to remove the back seat and find a gap which will allow you to easily run wire to the back. I usually find it best to first try to find a space where I can push my hand or fingers into the side gap of the rear seat (as the base of the top half of the rear seat) and find out if there’s a space available. If not, I’ll try using a the coat hanger trick, which almost always works!

Connect the positive wire to the fuseholder.

This should be very straightforward. Trim about 1/2″ insulation from wire ends and assemble the fuse holder onto the expose positive wire. Connect a crimp ring terminal and crimp using vise grip pliers (or other strong pliers) or a crimp tool.

Place the fuseholder near the battery with approx. 12″ or less of wire length, as that’s a general rule used to ensure there’s not enough wire to possibly be in a short-circuit without fuse protection which could cause a battery explosion or cause your vehicle to catch on fire. Don’t think so? It happens! It doesn’t take very much for a pinched, unprotected wire to start melting the insulation and for a fire to start.

Don’t install the fuse yet!

Image of a pair of crimp ring lug terminals Image of a pair of gold plated crimp ring terminals of 5/16" size

I highly recommend crimp ring terminals like those in the left picture, and not those in the right picture (lug terminals). It’s because lug terminals are far harder to crimp and may require soldering sometimes to make the best connection. 5/16″ ring terminals like those on the left are excellent and easier to use, as well as being included in many good amp wiring kits. If you can’t get the rubber sleeves to fit over your wire, don’t worry too much and leave them off if necessary.

Avoid lug terminals like those shown here. I’ve discovered that while they’re sold in some amp kits and are also sold in parts stores, they’re a terrible pain in the behind to use and are intended to be used with special high-force crimp tools. They may very well keep you from getting your amplifier wiring installed, and I don’t want that!

Connect the positive cable securely to the battery.

Use the ring terminal to fasten to a battery clamp bolt or stud. Use sandpaper or a wire brush to remove corrosion and expose clean metal if necessary.

Car amplifier positive wire and fuseholder installed at battery

For the best method, use a crimp ring terminal to attach the positive wire to the battery clamp on a stud or bolt. Be sure to remove the fuse before doing so, and install the fuse holder on the wire prior to connecting it to the battery. Hold in place by using zip ties to attach to nearby wiring, hoses, or brackets.

Connect the amplifier ground wire to bare metal near where the amplifier and subwoofer will be placed.

Use a crimp ring terminal and secure it to the car body (bare metal) with a factory screw or bolt. An alternative and faster solution is to use a cordless drill and self-tapping screw to drill into the metal and fasten the ring terminal simultaneously.

Car amp grounded to factory ground location

If you can find a factory ground wire location in close range it’s an excellent ground wire connection point. Otherwise using a self-tapping screw and a cordless drill make the work very quick.

Connect the remote-on lead to the aftermarket car stereo and signal source

If the stereo in use is an aftermarket model a remote lead output wire should be available (blue or blue and white). Connect this to your remote on wire included with your kit. If no aftermarket car stereo is installed, it will be slightly harder. In that case you have a few options:

  • Run the remote wire to a +12V wire switched on with the ignition or the accessory position of the ignition switch (this is the 1st choice)
  • Use a specialized adapter which senses music and when connected to a power supply can provide a remote lead signal

The 2nd option shouldn’t be necessary except in really tough situations. Nearly always you can find a +12V switched wire somewhere in the vehicle. It may take time, but using a good multimeter you can find one, then connect to it in the same way I’ll show you for the speaker level signal below.

car stereo remote on wire image

On most aftermarket car stereos a blue output wire is for switching an external amp on and off. It supplies +12V when the stereo is turned on. Connect to this if available. I normally use butt connectors (crimp connectors) for connecting wire securely.

Connecting the RCA cables – or connect speaker wiring if RCA jacks are not available

Remove your car stereo and get access the rear wiring or rear of the stereo if it’s and aftermarket (non-factory) model. Connnect to the RCA jacks if available in the following order of preference:

  1. Subwoofer output jacks (often marked SUB or SUBW)
  2. If 4 are available, use the REAR jacks
  3. If only 2 are available, then that’s fine as well

The left channel is marked with a white jack and red represents the right channel. However, it’s not as important for when you’re using a subwoofer rather than stereo speakers, but good practice to be consistent.

Rear of Pioneer car stereo showing RCA jacks

Plug your RCA cables to the rear of the aftermarket stereo, if available.

Connecting to speaker level inputs (if you have a factory system)

If no RCA jacks are available or you have a factory car stereo, you’ll need to tap off of speaker wiring to get an audio signal source. This may be easier to do while you’re connecting the remote wire at the stereo. If there are rear speakers in the vehicle, that’s another option too as speakers in a trunk may have fairly easy access to speaker wiring.

You need to find wiring information for your vehicle and check at sites like the12volt.com for wiring charts.

Image of rear car speakers being connected to an amplifier (taps)

Illustration for tapping onto speaker wires for getting an amplifier signal

At each pair of speaker wires or near the speaker wire connector, strip off about 1/2″ of insulation and tap off by either wrapping wire or cutting the factory wire and re-connecting it using crimp connectors while adding small gauge wire to each.

Crimp connectors (see the tool list at the beginning) are reliable and make good electrical contact. I recommend you use those if possible.

Image of car stereo wires crimped

Route wiring to the amp location

After connecting the power wire, remote wire, and signal wire move it down to the same side of the car (as needed) and when the wire comes together use zip ties (also called “wire ties”) to neatly hold it all together. Use wire cutters to cut off the extra remaining zip tie length.

Wire bundled with zip ties example

Bundle your power and cable wires together neatly like this. But you can space out zip ties much more to avoid using too many. 1 ft or more spacing between zip ties often works well. The ties hold wiring in place, make it more manageable, and help keep things from moving around.

● Mount the amplifier

For the average person there are 2 great and pretty simple ways to mount your amp so that it doesn’t move and have problems while the car is in motion:

  1. Mount the amp to the subwoofer box
  2. Mount a custom cut board to the car, then mount the amp to it

I personally prefer #2, as it’s a better looking and more professional method. It’s slightly more work than #1, but looks wonderful and it also avoids subjecting the amplifier to extreme vibration when mounted to a subwoofer box.

For option #2 you can buy nice speaker box carpet or a dark fabric from Joann or some other fabric/crafts store and cover the board using an adhesive spray and/or a stapler, then mount it using brackets or car stereo straps. Black fabric is available in a variety of fabric types (I’ve used black felt or velvet-like materials often for custom installations).

Another advantage of the board mounting method is that you are able to mount an amplifier in many places otherwise not possible: Just cut a section of board (purchased from Lowe’s or Home Depot) slightly larger than the amplifier, mount it using brackets or straps, and that’s it. As long as you have room and the parts for mounting the board, it’s relatively easy! You can find some great ones I use here.

Pan head screw #8

Car stereo strap

 

Use pan-head screws (left) rather than self-tapping screws when you’re mounting items to wood or wood-like materials. Car stereo installation straps (right) are fantastic for custom mounting amplifiers, amplifier boards, and subwoofer boxes to a car.

Car amp mounted to subwoofer box Car amp mounted to board in car trunk - custom install

Two amplifier mounting ideas that work for nearly all installations. Don’t sweat it! One of these should work. However the board mounting idea looks much better and means you can mount your amp out of the way in many cases.

Connect all wiring to the amp and the subwoofer

image of car amplifier having wire connected

This is the easy part! And you’re in the “home stretch” – there’s not much left at this point. If all goes well, you’ll have awesome sound really soon.

With the power turned off and power wire fuse removed, connect the power wire, ground wire, and remote wire to the matching terminals. Normally the positive and negative terminals are larger than the rest. Make sure you have a good, tight connection without any stray wires sticking out in a way that may lead to a short circuit.

Image with diagram of how to bridge an amplifier

Connect the larger speaker wire you bought to the speaker terminals of amp. If you’re using a bridgeable amplifier connect the wires to the amp in a similar fashion as shown here. If using RCA inputs, connect to the input pair for the speaker outputs you connected to.

If using speaker level inputs from a factory system connect them now. They should be labeled and/or color-coded to make it more clear.

Power on the system and check for problems

Install the power fuse and turn on the ignition and your stereo. You should hear sound and the amplifier power light should indicate that it’s on. If not, check the following items for problems.

quick tip
Use a test meter when possible for troubleshooting amplifier problems. Test lights don’t give you enough information. Many amplifiers can have a good ground and +12V battery connection but won’t turn on if the remote lead is below a certain voltage, for example, so it’s important to be able to find out what’s going on.

  • Poor car ground wire (measure continuity between the amp negative terminal and a metal portion of the car)
  • Fuseholder problem or bad fuse
  • Remote wire voltage is too low or +12V isn’t being supplied at all

Generally there are only a few reasons why an amp can’t turn on and produce sound, so it’s normally one of a few basic problems like I’ve listed here causing the problem.

Setting the gain and bass adjustments

The problem with having sound adjustments on both the stereo and the amplifier is that settings can be all over the place and one can affect how the other produces sound to your subwoofer.

I recommend doing the following:

  1. Turn off all bass boost or equalizer (EQ) functions on the stereo or set to mid level or zero.
  2. Turn off any bass boost controls on the amp or turn to the minimum level
  3. Set the amp gain to minimum

image of car amplifier controls

Play some music you’re very familiar with and that you know should have good bass sound at a moderate level. Then with a small screwdriver or screwdriver bit that fits, turn the gain up on the amp until the bass level is at you liking. Don’t forget that when an SUV hatch or car trunk is closed, the sound will be changed somewhat (for better or for worse) because of how the sound waves behave inside the vehicle.

So it may take a little while to get it where you like it.

Afterwords, try using the car stereo’s audio settings again to hopefully adjust the sound from there. In case the stereo has insufficient bass or your system still doesn’t sound quite right, try using the bass boost on your amp if available.

A bass boost typically works boosting bass tones near a certain low frequency like 50Hz, for example and can sometimes add some extra “thump” and bass extension to your audio system.

Congratulations! You’ve accomplished what so many people never could – you’ve installed your own car subwoofer system!

Summary

I hope my guide has provided a lot of helpful information. That’s what I’d love to do, because I want everyone to know how great it feels to install your own car subwoofer and amplifier. It can be a bit of a learning curve the first time you try but it’s a really helpful skill to have because once you’re bitten but the “audio bug” you can continue to make changes and advance your sound system even more if you like later.

One important tip: for factory installed “premium” audio systems like Bose, JBL, and Harmon Kardon it can be difficult as those systems can be far more complex and may have a complicated design. Generally speaking you should still be able to add a subwoofer by tapping off of a pair of factory speaker leads in most cases. But if you’re unsure or get stuck, I recommend using Google to find car owner forums as there’s a very good chance that someone has already done similar work and posted information out there.

If you run into problems or don’t feel up to the task consider getting an estimate and more information from a reputable car stereo shop. If they say your vehicle will require parts and add-ons not listed here be sure to ask why. Add-ons are a very big money-maker for car audio stores.

What ever you do, don’t feel intimidated. Follow my advice here to be better prepared and take your installation one step at a time. Nearly everyone can install their own subwoofer in their car and enjoy fantastic bass!

Recommended items

As I mentioned in my guide, I generally recommend using a multi-channel amplifier. Here’s a great list I’ve put together of some of the best affordable and well-performing models.

Here’s a very good and complete amplifier wiring kit to make the job easier (I’ve found some of the best values at Amazon).

One of the best car stereos I’ve found is this one over at Amazon. I’ve also written a full review on my site, too!

If you’re considering buying a powered subwoofer here are some great choices plus more information.

Print outs

  1. Basic how-to infographic (.pdf file)
  2. Car amp installation diagram
  3. Basic speaker wiring diagram for woofers
  4. This web page: How To Install A Subwoofer And Subwoofer Amp In Your Car – Illustrated Full Guide (.pdf)

Got questions or comments? Feel free to leave a comment below or let me know.

Your comments are welcome!

      Leave a reply

      CommentLuv badge