How to Install Subwoofer Amp – A Step-by-Step Guide

Installing a subwoofer in your car can make the music sound much better. Subwoofers play very low bass notes that you can feel as well as hear. But you need an amplifier to power the subwoofer properly. Putting in a subwoofer and amplifier may seem confusing if you haven’t done it before. In this guide, I will show you how to install subwoofer amp in simple steps.

I have installed many car stereos and can guide you through the whole process in a simple way. We will get the right subwoofer and amplifier for your car and budget. I will show you step-by-step how to connect the wires neatly through the car’s interior panels. Then we will mount the amplifier and subwoofer in good locations. I will explain how to set up the amplifier so it sends clear, powerful bass tones to the subwoofer.

When we finish, you will enjoy listening to music in your car much more. You will hear and feel deeper, richer bass notes. And you will know how to upgrade your car stereo all by yourself. So let’s begin – installing a subwoofer amplifier is easier than you think when done carefully one step at a time.

Choosing an Amplifier

The first step is selecting the right amplifier for your subwoofer and system goals. Here are some key factors to consider:

• Power – Look for an amp rated to power the wattage of your subwoofer(s). Add 25-50% overhead for headroom.
• Channels – You’ll want a mono (single channel) amp for subwoofers. Some offer variable low-pass filters and crossover settings.
• Ohms Stability – Check that the amp can run your subwoofer’s impedance safely, like 1-ohm stable for a dual voice coil sub.
• Features – Consider amps with built-in crossovers, bass boost, remote gain control, etc. to simplify the installation.
• Budget – Amp prices vary considerably. Stick to reputable brands from Rockford Fosgate, Alpine, JL Audio, etc.

When sizing the amp, it’s best not to push it to its absolute max-rated power. Give yourself some overhead so you don’t distort or damage the subwoofer. I recommend aiming for 50-75% of the amp’s rated power for your subwoofer configuration.

You can check my recommended subwoofer amps here: Best Car Amplifier for Bass – Top 10 Picks

Choosing a Subwoofer

The subwoofer is just as important as the amp. Here are the primary factors:

• Power Handling – Match the wattage rating of your subwoofer to the amplifier power.
• Woofers – Choose between single or dual voice coil subs. Duals offer wiring flexibility for 1-ohm stable amps.
• Enclosure Type – Sealed, ported, or bandpass enclosures have different sound signatures. Match to your cargo space.
• Mounting – Consider low profile, shallow mount, or sealed enclosure subs depending on available space.
• Brand – Stick with reputable brands like Rockford Fosgate, JL Audio, Alpine, and Kicker for quality and durability.

I typically recommend a 10-inch or 12-inch subwoofer in a properly sized sealed or vented enclosure. Dual voice coil subs provide wiring options and more excursion for deeper bass. Choose a sub-rated for more power than your amplifier to avoid overworking it.

Vehicle Prep and Electrical Upgrades

Before installation can begin, make sure your vehicle’s electrical system can properly power the new amp and subwoofer:

• Battery – Use a digital multimeter to check the voltage and health of the battery. Replace if needed.
• Alternator – Upgrading to a high-output alternator may be needed for large amplifier power.
• Big 3 Upgrade – Upgrading primary electrical cables (battery, engine, chassis ground) reduces voltage drop under load.
• Fuses – Install high-current fuses or ANL fuse holders near the battery to safely protect the new cabling.
• Remote Turn-On Lead – Run a wire from the head unit’s remote output to trigger the amp’s turn-on relay.

Completing any necessary vehicle upgrades like these beforehand ensures reliable power and protects your expensive new gear. Don’t skimp on the electrical – it makes a big difference in the system’s performance.

Amplifier Installation

Now for the fun part – installing the amplifier. Here are the basic steps:

1. Mount the Amplifier – Use the included mounting brackets and screws to securely fasten the amp in your cargo area or elsewhere out of the way.
2. Run Power Wire – Install an in-line fuse nearby, then run 1/0 or bigger power wire from the battery straight to the amplifier’s terminals.
3. Run Ground Wire – Use short, thick ground wire to connect the amp ground terminal to a clean, unpainted bolt near the mounting location.
4. Run Remote Turn-On – Tap the remote wire into the head unit’s remote output wire, then run it to the amp’s remote terminal.
5. Run RCA cables – Run high-quality, shielded RCA cables from the head unit’s pre-amp outputs to the amp’s RCA inputs.
6. Set Gain – Use a multimeter to properly adjust the amplifier gain to the head unit’s pre-amp voltage level per the manufacturer’s instructions.
7. Connect Subwoofer – Connect the subwoofer’s voice coils to their terminals on the amp according to the sub’s wiring diagram (single or dual VC).
8. Dress Wires – Neatly arrange all cables and wire ties so they don’t rattle or get damaged. Use wire loom as needed.

Make sure to verify all connections are secure and double-check your amp settings before playing any music. With any luck, your new amp should now be powered on and ready to go!

Subwoofer Enclosure Installation

The final step is mounting the subwoofer enclosure. Here are some best practices:

• Secure Bracing – Reinforce the enclosure mounting points with sturdy bracing or angle aluminum for a rock-solid install.
• Consider Accessibility – Mount the enclosure so the voice coils are easily accessible if service is needed later on.
• Ensure Venting – For vented enclosures, make sure the vent or port is unobstructed once mounted.
• Aiming – Adjust the enclosure angle or positioning to aim the subwoofer’s sound toward the listening area for the best output.
• Fiberglass/Seal – Consider using sound-deadening materials like Dynamat to seal any enclosure seams or holes for a cleaner sound.
• Dress Wires – Run the subwoofer speaker wire neatly from the amp to the enclosure and secure it with wire ties.

Follow the enclosure manufacturer’s mounting instructions. Test fit the sub and enclosure first before finally securing it. And there you have it – your system should now be fully installed!

System Setup and Tuning Tips

Don’t overlook some final adjustments and settings to get the most from your new subwoofer system:

• Set Crossover – Adjust the amp’s low-pass crossover frequency and slope to blend the sub seamlessly with your front speakers.
• Set Levels – Balance the subwoofer volume level control on the amp with your head unit’s bass, fader, and balance settings.
• Set Bass Boost – If available, use a slight bass boost (2-4dB) to compensate for road noise and give the lows some emphasis.
• Dynamat/Sound Deadener – Adding sound deadening materials in problem vibration areas can reduce unwanted boomy resonances in the installation.
• Stock Speaker Check – Often the stock speakers can’t handle amplified power. Replace them if they distort at high volumes.
• Enclosure Bracing – Adding internal bracing to vented boxes minimizes panel resonances for tighter, cleaner lows.
• Rear Fill – Adding powered speakers behind the rear seats gives the bass more space to fill out the cabin.
• Set Crossover Frequencies – Experiment crossing the subwoofer in at 40Hz, 60Hz, or 80Hz depending on your front speakers’ capabilities.

Proper setup makes a huge difference in the system’s sound quality. Don’t be afraid to experiment and adjust these settings until everything sounds its best!

Troubleshooting Installation Issues

Even with careful work, issues can still arise. Here are some common problems I come across and solutions that I find working:

• No Power – Check all fuse locations, the battery terminal connections, and that power/ground wires are fully seated in terminals.
• Distorted Sound – Common culprits are incorrect gain setting, bad RCA connection, faulty head unit, or poor speaker match to the amp.
• Buzzing Noise – Check for loose connections at the RCA inputs that could introduce noise. Add ferrite cores if needed.
• Sub Not Working – Verify the voice coil connection is tight and wired in phase with the amp channels. Check box venting.
• Rattles/Vibration – Add Dynamat or damping material to isolate problem panels causing unwanted noises.
• Low Output – Ensure the gains are properly set, sub enclosure size is correct, and wiring has good conductivity without voltage drop.
• No Remote Turn-On – Check the remote wire connection and that the head unit is outputting voltage on the remote wire when powered on.

With patience and methodical checking, you’ll uncover the culprit. Don’t hesitate to consult forums for extra troubleshooting help if needed either.

FAQs on Installing Subwoofer Amp

How do I connect my amp to my subwoofer?

You need speaker wire to connect the amplifier’s positive and negative output terminals to the subwoofer’s positive and negative speaker terminals. Make sure to match the wire colors for proper phase connection.

How to connect a subwoofer to a car? 

Run speaker wires from your car’s factory-amplified speaker output or aftermarket head unit to your amplifier. Then connect wires from the amplifier to your subwoofer’s positive and negative terminals. Ground the amplifier and subwoofer to the vehicle chassis.

What is the best way to connect subwoofer wires?

Twist the individual wire strands tightly on each connection to reduce interference. Use crimp connectors or solder joints to securely fasten the wire ends. Wrap electrical tape around connections for added insulation and protection.

How to install a sub with a built-in amp?

Mount the subwoofer enclosure in the trunk or other convenient spot. Run the power wire from the car’s battery to the subwoofer/amp and ground the unit. Connect RCA cables from the head unit’s pre-amp outputs to the line-level inputs on the subwoofer/amplifier.

How do I connect my subwoofer to my sound system? 

Run speaker wire from your head unit’s speaker outputs to an amplifier. Connect the amp’s output to your subwoofer’s input terminals. Power and ground the amp, then run an RCA cable from the head unit to the amp for the bass signal.

How do I connect my subwoofer to my amp without subwoofer output?

Use a line output converter (LOC) device. Connect it between your head unit and amp. Run speaker wire from the head unit to the LOC. Use RCA cables from the LOC to the amp’s low-level inputs to feed the subwoofer signal through the amplifier.

My Final Thoughts on How to Install Subwoofer Amplifier

With proper planning, installation, and tuning, adding a subwoofer amplifier can be a very rewarding upgrade. Stick to quality gear from reputable brands and take your time. Don’t rush and double-check all steps.

If issues come up down the road, revisit your installation and settings. Subwoofer systems require routine maintenance like recabling terminals and checking for loose connections that degrade over time.

I hope this complete guide has equipped you with the knowledge to confidently install your subwoofer amplifier. Feel free to reach out if you have any other questions during your project. Happy bass-playing and safe tuning!