Do you Need an Amplifier for a Subwoofer?

Whether you want to improve the sound in your car or at home, a dedicated subwoofer is a must. Subwoofers are essential to any audio system to produce deep and powerful bass. Like other speakers, they also require power to deliver bass. And that’s where amps/receivers come in.

An amp, short for an amplifier, increases the power of audio signals. In simple terms, an amp takes a small audio signal and makes it louder, allowing it to drive speakers or subwoofers.

Although some subwoofers come with built-in amps, others do not. And it raises the question of whether you can use a subwoofer without an amplifier. Also, do you need an amp for a subwoofer?

The answer depends on the subwoofer. There are two types of subwoofers: powered and passive. Powered subwoofers, also known as active subs, have a built-in amp, meaning they do not require an external amplifier. A passive subwoofer has no built-in amplifier, so it requires an external amplifier.

Generally, a subwoofer requires an amplifier to power it, even if it already has one. The power output from most audio sources is insufficient to drive a subwoofer independently.

What is a Subwoofer?

A subwoofer is a type of loudspeaker designed specifically to reproduce low-frequency audio signals, typically in the range of 20 Hz to 200 Hz or lower. These low frequencies, well known as bass and subwoofers, are specialized to produce deep and powerful bass, adding depth and impact to audio content, such as movies, music, and video games.

In terms of power, basically, two types of subwoofers are available.

Subwoofer that doesn’t need an amp

Some subwoofer comes with built-in amplifiers, also known as active or powered subwoofers. 

Active subwoofers are subwoofers that eliminate the need for an external amplifier. Active subwoofers that don’t need an amp allow you to connect directly with the audio source using an RCA cable or speaker-level connections.

They have their own controls for adjusting volume, crossover frequency, and phase, allowing for easy integration and customization in an audio system. Those who prefer the convenience and easy connection to add a subwoofer in their home theater system and small audio setups prefer these active subwoofers.

Some active subwoofers available in the market are ElectroVoice ZXA-1, Yamaha DXS12, and PolkAudio PSW.

Subwoofer that needs an amp

There are also subwoofers that can only drive with an external amplifier to power them. These subwoofers that need an amp are called passive subwoofers.

Passive subwoofers do not have built-in amplifiers and rely on an external amplifier to provide power and drive the speaker. They typically require a separate amplifier that is specifically designed for subwoofers, as they often require more power to produce low-frequency bass sounds effectively. 

These speakers are commonly used in large audio setups, professional audio systems, or custom installations where more control and flexibility in amplifier selection and configuration are desired.

Some impressive passive subwoofer models are Yamaha SW21, Bose B1, and JBL PRX4.

Why do you need an amp for a subwoofer?

As I mentioned earlier, even an active subwoofer can be connected to external amps. It will strengthen the weaker signal, which leads to clearer and overall improved audio quality.

Here are some of the reasons you need an amp for a subwoofer.

Power requirements

We have discussed that a subwoofer requires additional power to reproduce deep bass and tremble. The subwoofer can work at its total efficiency and deliver optimum sound quality by getting a sufficient power supply through an amplifier.

This results in a louder and clearer bass response without burdening the receiving end to strengthen the signal. It also helps to reduce the load on the head unit, which prevents electric shocks and breakouts from damaging the wires and resistors. An amplifier will efficiently distribute the power so all the components can deliver the best performance.


Using an amplifier will enhance the efficiency of your sound system. With a proper power supply, all the speakers can produce louder sounds and more apparent notes without distortion or a loading effect. 

It also saves the electric circuitry, and you can quickly get your desired bass response without compromising sound clarity. 


By integrating an amplifier, you can have more control over your bass output. Amplifiers have additional features and function buttons through which you can adjust the impedance and gains to fine-tune your output as you like. 

You can select a range for your bass and treble to play or modify it according to the music or movie you are playing.

Sound Quality

The sound quality is the biggest reason to have an amplifier to power your subwoofer. With the basic need of a subwoofer to reproduce missing sound notes, you surely don’t want to hear distorted noise containing notes at high volume. 

That happens due to the burden of receiving end amplifiers or head units that make the sound appear unclear at higher volumes. With an amplifier, you can enjoy deeper bass and powerful sound output without any noise in the channel or disturbances due to electrical loading.

Can you use any amp for a subwoofer?

While it is technically possible to use any amplifier for a subwoofer, it is not always advisable. Here are some aspects to ponder when choosing an amplifier for your subwoofer:

Power Output

Check on the power requirements of your subwoofer and get an amplifier with a higher power rating so that there is no power shortage and you can enjoy louder and deeper bass and tremble without an issue. 

Also, if you use the amplifier for multiple speakers, ensure a proper power supply and distribution so that no one is skimped on power. Check the RMS rating on your subwoofer and pick an amplifier with about 70 to 150 percent more output power.

Frequency response

Another factor in picking the suitable amplifier is to check the frequency response of the amplifier. To get good treble and bass- it is advisable to have an amplifier with a frequency response ranging between 20-20KHZ.


Impedance or total electrical resistance in the signal flow is another critical factor in deciding on an amplifier. So it would be best to pick an amplifier that adds an ample impedance to the channel with subwoofer impedance and lower the power requirement.

Using a too-small impedance amplifier will consume more power and might also damage the wires and amplifier.


Checking the compatibility and connection ports of your head unit of a stereo system is an essential factor to consider before buying an amplifier. 

Check carefully that your head units have pre-amp output ports connected to the input of amplifiers, so you can be free from buying extra adapters and connectors.


Lastly comes the features and added control to your amplifier. With more options and gains, you can have better control over your sound system and modify it as required.

There is no denying the fact that an amplifier is an essential component for your sound system if you want to hear powerful bass and clear notes. 

An amplifier will save your system from burdening and reducing the overall sound quality, and it protects the power source from short circuits or tripping. Moreover, you get more control and tune the output as you like, which is impossible with just a subwoofer, and that too with increased range and easy installation.

So immerse yourself in the rich and appealing sound environment with louder and crisp notes that will amp up your whole movie or music experience.


Whether you need an amp or not for a subwoofer depends on the type of subwoofer you have or looking to purchase. Active subwoofers do not require an external amp as they have been built in, whereas a passive subwoofer requires an external amplifier to power them.

However, you can use an active subwoofer or a powered subwoofer with an external amp. An external subwoofer amplifier can offer several advantages, including increased power, greater control over sound quality and performance, flexibility in system configuration, and improved efficiency.

You also need to ensure you choose the right and compatible amp for your subwoofer.

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