Mono amps offer maximum bang per buck for driving subs, as they deliver more power at lower impedances.
2 Channel Amps:
Use a 2-channel amplifier to power a set of speakers, or switch to mono mode to drive a sub.
4 Channel Amps:
4-channel amps power your front and rear speakers, or switch to 3-channel mode to run speakers and a sub.
5 Channel Amps:
5-channel amps power your entire system: 4 channels for front and rear speakers, plus a sub channel.
6 And 8 Channel Amps:
6- and 8-channel amps give you incredible versatility in setting up your system, particularly with a 3-way setup.
You can stream music directly to a Bluetooth amp, great news if there's no room for a receiver in your vehicle.
Vehicle-specific amps & processors:
These amps and processors allow you to replace the factory amp in a premium system without losing any of your vehicle's features or functionality.
Learn how to install an amp in your car In this overview, we'll cover walk through a typical amplifier installation to see the steps involved when you install an amplifier in your vehicle.
How to install a car amplifier. Adding a car amplifier will let you play music louder. It'll also raise the sound stage and enhance the detail in every song at any volume. Let's take a look at what it takes to install a car amplifier in your vehicle.
In this video, we have one of our tech support advisors helping out. These are the same folks you'll talk to if you have questions during your install.
Find a place to mount your amplifier
Before you get started, find a suitable place in your vehicle to mount your amplifier. Amplifiers generate heat, so adequate ventilation is important. And you'll want to place it somewhere that's not too difficult to access.
Amp wiring kit and speaker wire
Your amplifier does not come with the necessary wiring, so be sure to purchase an amp wiring kit that includes power and ground wiring, as well fuses you'll need. You'll also need to purchase enough speaker wire for the job.
Disconnect the battery
First, disconnect the negative battery terminal to protect you and your gear during installation.
Running power wireNext, run the power cable from the battery to the amp. Cut a short piece of the power cable, at least 18" long enough to cover the distance from the battery to the fuse holder location, and strip the insulation off both ends. Crimp the terminal ring from your wiring kit to one end, and attach the fuse holder to the other end. Strip the insulation from the end of the wire that leads to your amp and attach it to the other end of your fuse holder. Assemble the fuse and holder, and attach the terminal ring to your positive battery terminal. Then mount the fuse holder securely. It’s important to keep the fuse close to the battery since the lead between the terminal and the fuse is unprotected.
In most vehicles, you can pass the power cable through the firewall that separates the engine compartment from the main cabin using an existing entry point. Once you're inside the cabin, tuck the power cable under trim panels or your carpet along one side of your vehicle until you reach your amp location.
Running turn-on wire and signal cablesAfter running the power wire, the next thing to do is run the turn-on wire and signal cables. The turn-on wire is included in your amp wiring kit. Run these cables behind the dash to your stereo. The turn-on wire connects to a remote turn-on lead in your stereo's wiring harness. It's usually blue, but confirm this with your owner's manual. Plug the RCA cables into the appropriate RCA outputs on your stereo.
Run these wires, the turn-on wire and the RCA cable, down the opposite side of the car from the power wire. This will prevent electrical noise from entering your system and spoiling your music.
All of this assumes you have an aftermarket stereo with pre-amp outputs. If you have a factory stereo then you'll do things differently. First off, make sure your amp has speaker-level inputs and "signal sensing" turn-on capability. If the amp does, you can just tap into the speaker wires behind your stereo, or possibly the rear deck speakers, to get signal to the amp.
Ground the amplifier The third primary connection is the ground wire. This wire should be connected to the vehicle's chassis. Look for a nearby bolt that you can fasten the ground cable to. The ground wire terminal should be in contact with the vehicle's bare metal. Sand away any paint at the contact point for the best connection.
Send signal from your amp to your speakers Now you need to get that audio signal from your amp to your speakers. Run this speaker wire at the same time you run the amp input wires.
If you're powering speakers with more than 75 watts per channel, then you should run new speaker wire from the amp to each speaker. If your amp is only powering subwoofers, then just run speaker wire to the subwoofer box. Either way, use 14- or 16-gauge wire from your amp to your speakers.
Now, mount your amp and make your connections. Try to use gentle curves with your wires and cables when possible.
Before you fire up the amp to test, turn the amplifier's gains all the way down. And if you’ve disconnected any connectors relating to the airbag, make sure to reconnect them. You don’t want to trip an error light that’ll need resetting. Now, reconnect your vehicle's negative battery terminal. Verify that the amp turns on when you turn the car on. Then you can play some music and set your gains.
Electrical Term Definitions
Here are some useful electrical terms related to calculating volts to watts, watts to amps, and volts to amps.
What wiring and accessories do I need? Car amplifiers don't come with any wiring included. You must supply the amp's power and ground wiring, an inline fuse, a remote turn-on wire, RCA cables, and speaker wires.
Power and ground wires The power and ground wires need to be thick enough to accommodate the amp's demand for electrical current or the amp won't operate properly or put out its rated power. Your amp's instructions will include a recommendation on what size wire to use. Or, you can check out How to determine the best size wire for help doing it yourself. Don't forget to measure all distances first, so you'll know what lengths of wire to get.
The fuse that will protect your system The in-line fuse on the main power cable, mounted within six inches or so of the battery connection, is essential for protecting the wire, your car, and you from a catastrophic fire in the event of a short circuit. Each wire manufacturer rates their wire's current capacity differently, but as a general rule, for a typical 16- to 20-foot run, you'll be safe using a:
An amplifier wiring kit The easiest way to get these items is with an amplifier wiring kit, which will include matching power, ground, turn-on wires, and fuse.
RCA cables and speaker wire Amp wiring kits often don't include signal wiring. Your amplifier gets its input signals from the receiver's output typically via RCA cables. RCA cables come in stereo pairs, in various lengths. When running new speaker wires from your amplifier's output to the speakers, any size wire from 18- to 14-gauge will work fine. (The lower the gauge number, the thicker the wire.) For subwoofers, use 16- to 12-gauge wires.
Where should I mount my amp?Use these guidelines to choose a location for mounting your amplifier. A smart mounting location will help your installation go smoothly:
Good locations to install an amplifier include:
Boyo trim panel tools
The instructions below address, in general, which panels may need to be removed and how they typically come off. Often, panels can be pried up at the edges. You'll probably also need to remove some screws and retaining clips (Figure 1). To prevent damage, always use care when removing panels — a panel tool is helpful.
Screws and retaining clips might be present that will require removal
Removing the door scuff plate The plates are usually removed by prying up the edges to release clips. Some vehicles will have screws present which will need to be removed (Figure 2).
Removing the seat beltA seat belt may be located on a panel that needs to be removed. Most seat belt anchor covers pry off. The seat belt anchor is secured with a large nut or bolt (Figure 3).
Removing the pillar trimpanel Remove the seat belt if present. Remove screw covers, screws, and plastic retaining clips if present. Pry up the edges of the panel to remove it (Figures 4 & 5).
Removing the kickpanel Look for screws and pry-out retaining clips to remove. Pry out the edges of the panel to release and remove it (Figure 6).
Routing wire behind the dashWhen routing wire behind or under the dash, always secure it with plastic wire ties. Be sure that the wire doesn't interfere with any moving parts to ensure safe operation of the vehicle.
Time to install the amplifierWith that background stuff covered, it's time to get to work. Gather up your gear and tools, maybe a friend and a soda, and give yourself plenty of time.
Step 1 — Disconnect the batterySet the parking brake and disconnect the negative terminal from your battery to prevent any electrical shorts or shocks.
Step 2 — Mount the amplifierMount your amplifier in the location you've chosen.
Step 3 — Install the power wireThe power wire from your amp wiring kit (usually 16-20 feet in length) needs to run from the battery, through your car's firewall, through the car's body to the amp. Find an unused grommet in the firewall or one that already has wires or cables passing through it and that has enough room for the power wire to fit through too.
Route the power wire from your amp wiring kit through a hole in your vehicle's firewall, using a grommet or bushing to prevent the insullation from scraping against metal.
If you can't find an existing grommet, you'll have to drill a hole through the firewall. Make sure you don't drill into any electrical or gas lines — check both sides of the firewall. Use a grommet to protect your wire from fraying and shorting as it passes through the hole.
Step 4 — Install the fuse holderThe power wire from your amp wiring kit may have a fuse holder installed. If so, go to Step 5. If not, find a good spot close to your battery to place your fuse-holder (included in the kit) — less than 6" from the battery is best. Be aware: even after a fuse blows, the short stretch of cable between the battery and the fuse holder will still be live and a potential fire hazard in the event of an accident. Anchor the fuse holder to a suitable spot with a screw or cable tie, so it won't hang loose or bounce around.
Fuse installed on power wire, and secured in engine compartment near the battery.
Cut a short piece off the end of the power wire (to cover the distance from the battery to the fuse holder location), and strip the insulation off both ends with a wire stripper. Crimp the terminal ring (included in the kit) onto one end of the short piece of wire, and attach the fuse holder onto the other end. Strip the insulation off the end of the power wire that leads into the passenger compartment, and connect it to the other end of the fuse holder.
Multi-amp installationsWhen powering multiple amplifiers, you run a single heavy-gauge power cable from your battery to a distribution block, and then connect a lighter-gauge cable from the block to each amplifier. This arrangement minimizes potential noise problems and keeps your installation looking neat. Make sure the main power cable is thick enough that it can handle the total current draw of all the amplifiers.
Check out our amplifier wiring diagram to see how the wiring gets connected in a typical 2-amp system.
Step 5 — Connect the power wire Attach the power cable to the positive battery terminal (not directly to the battery post itself). For top-mounted battery posts, the most common way to do this is to crimp a ring terminal onto the end of the power cable (many cables in wiring kits come with it already attached). Remove the battery terminal's nut, slip the power cable's ring over the bolt that secures the battery terminal to the battery post, and replace the nut. For GM vehicles with a side-mount post, we offer terminal adapters that work nicely.
A wire loom provides added protection for your wire against the high heat inside the engine compartment. If your kit includes a wire loom, thread it over the power cable until it reaches the firewall and cut to fit. Thread another piece over the short power wire running from the fuse holder to the battery.
Step 6 — Ground wire: the most important connection of all As near to the amplifier's location as possible, find a bolt to your vehicle's metal frame to use for ground. If you can't find a convenient ground screw or bolt, drill a hole for one — be careful not to drill into any wiring, the gas tank, or a gas or brake line. Crimp a ring terminal (usually included with the amp kit) to the short piece of ground cable (also in the kit).
EFX Ultimate Ground Terminal
Scrape away any paint and clean the bolt location thoroughly, and then bolt the terminal tightly to the vehicle's metal chassis. Use a lock washer, a star washer, extra screws, and any other technique or device that'll keep this connection tight, clean, and electrically conducting. Many people even coat the final connection with silicone caulk to prevent corrosion.
Scrape the paint away from the contact point so the ground connection will be bare metal to bare metal.
Improper or loose grounding is the #1 cause of amplifier problems.
Step 7 — Install the remote turn-on wireThe turn-on wire (also called the remote wire) is located behind the stereo. On aftermarket stereos, it's usually a blue and white wire. The remote wire will "tell" your amplifier to turn on whenever the stereo is powered up (usually, whenever the vehicle is turned on). You'll have to remove the stereo to get to this wire. For step-by-step instructions on removing your vehicle's radio, see your vehicle-specific Guide.
Locate the remote turn-on lead behind your radio (usually a blue and white wire), and connect the turn-on lead from your amplifier wiring kit to it.
Strip the insulation off a small section of this wire coming from the radio and the turn-on lead that came with your wiring kit and connect them together via solder, a crimp connector, or a Posi-Connector.
The turn-on signal is +12 volts DC. If, like a factory radio, your radio doesn't have a remote turn-on output, then you can get the turn-on signal from your vehicle's fuse box. Because of its low current demand, you can connect your turn-on lead to almost any fused output terminal, like the one for the radio itself for instance, as long as it only powers up when the vehicle's on. Using an Add A Fuse connector plus a 2A to 10A fuse will make this connection easier.
You'll need to route the turn-on lead to your amplifier through the car's body — it's often easiest to route the turn-on wire with the RCA cables (next step) but you can also route it with the power wire after it passes through the firewall. The power and RCA cables should run on opposite sides of the vehicle, to reduce noise — but it won't matter for the turn-on lead's low current.
Step 8 — Making the signal connections If your in-dash receiver has preamp (RCA) outputs, connect your RCA patch cables to them. Route the patch cables to the opposite side of the vehicle from the power cable. It's important to separate the patch cables from the power wires as much as possible to avoid potential noise problems. Now you can partially re-install the radio in the dash. Avoid completely re-installing it if you can, in case you need to fix a problem later.
If you're using a factory radio with no RCA outputs, you can get your amplifier's input signals from the factory speaker wiring. The speakers will be getting their signal from the new amplifier — which leaves the radio's outputs available to use for the amp's inputs. There are two ways to do this: get a line output converter (LOC) that'll adjust the speaker-level signal for your amp's input, or get an amplifier with speaker-level inputs. You cut the factory speaker wires behind the radio, and connect the wires coming from the radio to your LOC or amp's inputs.
Scosche SLC4 Line Output Converter
Learn more about line output converters.
Step 9 — Speaker wiringNow you have to provide a way for the music to get from your new amp to the speakers. The best way to do that is to run a new speaker wire from each amplifier output to each speaker. Use 14- or 16-gauge wire for speakers, 12- or 14-gauge for subwoofers. Speaker-level signals are not very prone to picking up interference, so it's okay to run your speaker wires near power cables.
You'll have to run each wire for your door speakers through the rubber gasket or boot around the hinge, to protect the wires from the weather or from getting pinched in the door. There may be a Molex plug or a similar obstruction blocking the way, but you can usually find a place to drill a hole through it big enough to fit your wire through. Disconnect or cut the factory speaker wires and connect the new wires directly to each speaker terminal.
It is important that you keep the polarity of your speaker wiring straight. This means that each positive terminal of the amp connects to a positive terminal of a speaker — and the same goes for the negative terminals. This ensures that your speakers will operate in mechanical phase — all the speaker cones moving the same direction with the same kind of signal — and will sound balanced when playing together. The positive and negative terminals of each speaker should be labeled, but if not, the positive terminal will usually be wider than the negative terminal.
Use your factory speaker wiring Another and much more convenient way to send the powered signal from the amp to your speakers is to run the speaker wires to the harness that’s behind your receiver, where all your car’s speaker connections are accessible in one place. You cut each speaker wire from the receiver's harness and reconnect it to a speaker wire coming from the amp. Then, the signal can flow from the amp to the speakers by way of the vehicle's original factory wiring. This technique will work fine in systems with up to 75 watts RMS of power per channel — but for more powerful systems it would be better to run new speaker wire directly from the amp to each speaker.
Check out How to connect an amplifier to a factory stereo to see how this can be done.
Step 10 — Connect all the wires Neatly drape or trim each wire and connect it to the amp. Make gentle curves with the wires, not sharp bends that could pinch. Many people cut small slits in their vehicle's carpeting and run their wires underneath, for stealthy installations that look factory-neat. A wiring snake comes in handy for this. Tape your wires to the snake, fish it under and through to where you want your wires to go, and pull them on through.
RCA cables routed through slits in the vehicle's carpet, and connected to the amplifier's signal inputs
Step 11 — Turning it on Check all of your wiring, from the battery and receiver to the amp and speakers, making sure every connection is tight and secure with no stray wire strands laying out that could cause a short circuit. Especially, check that the ground connection is tight and secure. Set all the amplifier's gains to minimum, and turn off all the filters and any bass boost or EQ it may have. See that the main fuse is properly installed in its holder. Then, reconnect your car's negative battery cable.
Turn on your car, then turn on the radio. Verify that the amplifier powered up (there'll probably be an indicator light on it somewhere). Play some music and turn the volume up just loud enough to hear. Now verify that sound is coming from each speaker and/or subwoofer in your system. If everything sounds right, you can finish re-installing the stereo and all your vehicle's paneling, and then move ahead to step 12.
If things aren't working as they should, see the Troubleshooting section below.
Step 12 — Setting the amp's gainSetting your amplifier's gain, or input sensitivity, matches the amp's input level with the receiver's output level, resulting in maximum distortion-free music and minimum background noise.
Setting the amp's gain
For a detailed explanation of how to do this, read our article about setting the gains on a 4-channel amplifier. If you’re installing an amp for a subwoofer, read How to tune your subs. The approach is the same, we’ve just tailored the explanation to each situation.
Enjoy your new system.
Troubleshooting your amplifier installation Sometimes things just don't work like we expect them to right from the start. Here are some of the most common problems that can occur when installing an amplifier.
Factory radios and their security codes If you're using a factory radio, it may need its anti-theft security code reset. If so, you can usually find the code and resetting procedure in the vehicle's owner's manual, online, or from a car dealership service department (be prepared to prove you own the vehicle).
Amplifier doesn't power-up In order to properly and safely troubleshoot a malfunctioning electrical system you'll need to use a multimeter to measure voltages and check continuity. Crutchfield sells the Install Bay 3320 digital multimeter, but if you're in a hurry, you can probably find one at your local hardware or electrical supply store.
One common symptom of over-powering is the dimming of lights when bass notes hit. If your lights dim just a little during heavy bass passages, you might benefit by installing a capacitor on the bass amp's power cable. Otherwise, check out Headlights dim when the music plays to help solve over-powering issues.