How To Hook Up A Subwoofer To A Car Without An Amplifier 

Norvan Martin

Installing a subwoofer is one of the best ways to improve the sound quality of your car audio system. A good sub helps you augment the bass experience. However, some subwoofers generally require an amplifier, but what if you don’t have one? In this article, we discuss how to install a subwoofer into a car without an amplifier.  

Hooking up a subwoofer onto a car without an amplifier is pegged on the type of subwoofer, whether passive or powered. Please ensure that you are using an aftermarket stereo with preamp outputs.

Connecting A Passive Subwoofer

A passive subwoofer is without a built-in amplifier, and connecting such a sub to a car is not different from connecting to any other speaker. 

Step 1: Disconnect The battery And Remove The Speakers

Begin by disconnecting your battery completely. Then, remove your speaker from the mounting dock to give access to its wiring. This could be the speaker wires behind your stereo or rear deck speakers.

Step 2: Mount The Subwoofer

Mount your subwoofer in your preferred location in the car, and ensure that you have existing speaker wires in the area where you will install the subwoofer.

Step 3: Re-route The Stereo And Finish The Connection

Finally, re-route the stereo and power supply cables to the subwoofer and connect them. If your audio system has an outlet for your subwoofer, equally connect that.

Note that you will not get a shattering bass by wiring the rear speaker output; instead, you will get a lower bass frequency in comparison to the speakers. 

If by any chance there are no existing wires, drive wires from the head unit harness, the same way as you would for the car speakers. 

Please make sure that the ground wire is connected to the vehicle’s chassis. Just connect it somewhere to the vehicle’s bare metal. It could be a metal bolt or something similar. Just remember to send the paint before connecting.

Step 4: Reconnect the battery

Turn the subwoofer’s built-in amp gain down and reattach the car’s battery terminal.

Step 5: Check Your Audio System

Check your audio system to ensure everything is working properly, including your subwoofer!

Connecting A Powered Subwoofer

A powered sub will hook to the stereo, in the same way, a standard amplifier will. Follow the steps below to complete the connection process. 

Step 1: Assemble The Materials

Begin by assembling the suitable material. Here are some of the materials you will need to complete the connection. 

  • Spanner 
  • Hammer, 
  • Tester, 
  • Screws and 
  • Pliers. 

Step 2: Power Off The System

Disconnect the electric system – detach the negative battery cable from the battery negative terminal to avoid shock since a subwoofer is an electric component.

Step 3: Shut Off The Infotainment Components 

Disconnect all the lines leading to the broadcasting system to avoid accidental shocks while accessing the rear panel.

Step 4: Remove The Fuse 

There are mechanisms in the fuse box you need to apply before the installation process. Therefore, removing the fuse allows for the connection of the subwoofer and the main power supply.  

Step 5: Detach The Stereo From the Dashboard 

Using a flathead screwdriver, disconnect the speaker from the vehicle’s stereo mounting dock to access the wiring harness and outlets on the stereo, rear panel. You can also use the rear deck speakers instead.

Step 6: Attach An Adapter With The Stereo Wires 

An adapter acts as a power outlet for your subwoofer. A combination of the adapter and the stereo wiring will provide the final power source, hence the connection through a single cable.

Step 7: Place The Subwoofer 

The placement is a very significant step in the connection process. While setting up, create a crossover connection between your sub and car stereo. Thus looking for the right rear panel in your car is very pertinent.

Step 8: Connect The Low-Frequency Effects 

Connect LFE to the output port of the subwoofer. It might be labeled “subwoofer” or “sub-out.” This label is for subwoofers only and is usually the only RCA port, making it easily identifiable. Note that you should not run RCA and power cables together, for they can cause sound distortions. 

If you don’t see the LFE output or the subwoofer is missing the input, try to find the left and suitable stereo connectors (sometimes indicated as R and L). If the Line uses cables, plug it into the L or R on the subwoofer box.

Follow the procedure below to make sure your connection is safe. 

  1. Make sure the negative pole is connected to the negative and positive with the positive. Use a tester to test the flow of the electrical current to make sure the crossover and everything is working smoothly. 
  2. Place the subwoofer back into its holding, ensuring that you use the only metal-to-metal connection without any paint between the car body and the wire. 
  3. To this point, you should make all connections. Place the earlier removed ground battery wire on the battery negative terminal and screw it back. This will ensure a stable connection.    

Step 9: Grounding

Please make sure that the ground wire is connected to the vehicle’s chassis. Just connect it somewhere to the vehicle’s bare metal. It could be a metal bolt or something similar. Just remember to send the paint before connecting.

Step 10: Check Your Audio System

Check your audio system to ensure everything is working properly, including your subwoofer!


How Does A Car Subwoofer Work?

A subwoofer produces deep thumping bass, something that standard speakers cannot offer. Subsequently, any sound system without a substantive subwoofer sounds very flat. A car subwoofer delivers low-frequency audio, leaving the tweeters to create high-frequency sounds like the vocals. 

Additionally, the low frequency reproduced is typically in the range of 20Hz to 100Hz. Studies have indicated that human ears can hear between the degrees of 20Hz to 20,000Hz. 

Installation of a subwoofer onto a car does not matter where in the car it is done. A sub is not dependent on placement because low frequencies do not need directional projection toward the ears. You can install it in the trunk, below the seats, or even inside the spare wheel. 

Can I Connect A Subwoofer Directly To A Car Stereo?

Generally, some subwoofers (passive subwoofers) require an amplifier to function properly. For example, a common setup is to connect a passive subwoofer to a 2 channel amplifier. This is because passive subwoofers do not have built-in amplifiers.

You may want to connect a subwoofer directly to a stereo because you don’t have the budget for an amplifier. However, check out our guide on how much to get subwoofers and amplifiers installed if you have an old am lying around before you decide on this. 

Can I Connect A Subwoofer Directly To A Car Stereo

To avoid using an amplifier, you can instead connect the subwoofer to the car stereo using a powered subwoofer. A powered or active subwoofer already has a built-in amplifier. This saves space in your car and eliminates the need for an external amplifier. However, they won’t be as powerful. 

If you have a powered subwoofer, just remove one of the speakers from the mounting dock, reroute the wires to the subwoofer, and mount the sub. If your audio system has an outlet for your subwoofer, connect this as well.

In addition, you can check out our guide on how to connect a subwoofer to a car stereo without an amp or how to connect a subwoofer to rear speakers in the car

Can You Put A Subwoofer In Your Car Without An Amp?

Indeed, a sub needs an amplifier to run the transducer. The amplifier’s job is to amplify the signal, which is required by large magnets in the bass speakers. 

Subwoofer drivers only accommodate power to some limit. For instance, a 1000 W sub works from 0 to 1000 W; depending on its sensitivity, you should have the sub work with 1W. A subwoofer needs twice the power you feed to the rest of the speakers to reap reasonably in terms of audio quality.

Therefore, subwoofers sound very muffled and deep, and you tend to ‘feel’ the sound rather than hear it. There is no definition of sound at all, just a dull vibration. 

By extension, a subwoofer brings three main benefits below to your car: 

  • Clear and real audio
  • Low distortion and 
  • Louder sound

Can you put a subwoofer in your car without an amp? As we already mentioned, passive subwoofers will need an amplifier for a better sound experience. However, if you have a powered subwoofer, you will not need an external amp as powered subs come with inbuilt amps. 

How Can I Get Bass Without A Amp?

Bigger amplifiers can be costly to buy. You can check out our guide on how much it costs to get a subwoofer and an amplifier installed to learn more. Nevertheless, getting bass without an amplifier is still effortless. Here are some tricks that will help you harness bass from your subs even without an amp. 

Step 1: Put The Sub In a Corner

Placing the subwoofer in a corner offers you more bass boost with the potential to give you up to six decibels of bass boost without requiring toad an amplifier. 

Step 2: Ensure the whole System Is In Phase

Make sure the subwoofer is in phase with the car stereo. Most subs come with a phase switch that makes it easier to vary or offers a 0-degree and 180-degree position. Play some bass with the sub and adjust to the loudest bass using the phase switch

Step 3: Change The Position Of The Subwoofer

Place the subwoofer in an asymmetrical position relative to the boundaries of the car to get a much louder bass output. 

Step 4: Fine Tune The Subwoofer Crossover Controls

If you operate subs with improperly adjusted crossovers, the main speakers and subwoofer will most likely compete in the bass frequencies and cancel each other out. Adjust the crossover properly to get louder bass. 

Which Subwoofer Can I Connect To A Car Without An Amp? 

If you still want to have clear and sturdy bass without including an external amplifier in your car, then consider installing a powered subwoofer. Active subwoofers have built-in amps and will work without an external amp.  

They are usually presented in different sizes and shapes and are available on Amazon. Some of the subwoofers you can connect to a car without an amp include:

1. Under-Seat Subwoofers 

These subs are ideal when the trunk has limited space. Some of the under-seat subwoofers you can connect to your car without including an external amp include:

  • Rockford Fosgate PS-8 Punch
  • Rockville RSW12CA Slim
  • Kicker 11HS8 Hideaway 

2. Bass Tubes 

Bass tubes consume relatively limited space, especially when the car is tiny. A perfect example is the MTX Audio RT8PT

3. Spare Wheel Subwoofers 

Spare wheel subwoofers are ideal if you have room in the spare wheel area of your car. No trunk space shall be in use at all. Choosing the right subwoofer depends on individual preferences and installation possibilities. 

One of the best spare wheel subwoofers to add to your car without an amp is JBL Basspro Hub

Does A Powered Subwoofer Need An Amplifier?

Unlike passive subwoofers, powered subwoofers come with built-in amplifiers and don’t need help from another receiver or amplifier to work. This ensures they are easy to use in combination with the average home-theatre receiver. All home theatre receivers come with pre-amp line outputs.

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Norvan Martin is the founder of He is a professional Electronics Engineer and is passionate about home theater systems and AV electronics. BoomSpeaker was created as an online hub to share his knowledge and experiences as it relates to home theaters and home audio electronics. My email: [email protected]  Connect on Pinterest and Linkedin