Matching Subs to Amps

Matching Subwoofers To Amplifiers – How To

Both subwoofers and amplifiers are important components of an excellent sound system. While the amplifier strengthens the sound’s signal and drastically increases volume, the subwoofer works as a type of speaker that reproduces the lowest bass sounds.

Subwoofers powered by amplifiers are an integral element in a high-end and high-performance car system. While there are several brands and sizes of the best subwoofers in the market, there are also several brands of amplifiers with different power settings and configurations.

In order to get the best out of your car’s sound system, it is important you know how to match the correct subwoofer to the right amplifier to get great bass.

Unfortunately, you cannot simply choose any amplifier off the shelf and expect it to match with the subwoofer. Luckily, we have created a guide to help you do so:

Things To Consider


When opting for an amplifier for a car subwoofer, keep in mind that single-channel (or mono) amps are usually the best in the market. Such amplifiers process single audio signals using only a single channel that is wired to the subwoofer to produce awesome bass sound. While you can wire up several of the best subwoofers to a single channel, each subwoofer will receive the same mono frequency.

mono amplifier

Low-end frequencies generally do not create an impact and are not heard stereophonically, such as the high-range and the mid-range frequencies that your car speakers produce, hence one channel is all you require.

If you are further looking for ways to improve sound quality, invest in an amplifier that has filters and offer tone controls that enable the user to optimize the bass reproduction.


Impedance is another important factor that you cannot ignore while trying to match the subwoofers to the amplifier. In simple terms, impedance is the measure of electrical resistance.

Matching the impedance with the amplifier is much like matching a water pipe to the sink’s faucet. Without the right pipe, the water simply won’t flow efficiently.

The size of the pipe needs to match that of the faucet and can neither be larger or smaller. Impedance pretty much works the same way. If you do not match it correctly, the amplifier and your subwoofer can over-heat, directly resulting in terrible audio.

Most typical car subwoofers in the market offer you the option to choose a model with an impedance of either 2 ohms or 4 ohms. Matching the impedance may seem like a simple concept. It gets even simpler if you simply install just one or two subwoofers.

However, things can get complicated if you are dealing with multiple subs or dual-voice coil subwoofers that have 2 input and output connections. For example, if you intend on installing two subwoofers of with 4 ohms, you must opt for an amplifier with 8-ohm impedance.

If you have purchased a dual-voice subwoofer powered 2 ohms, you need to attach an amplifier with a 4-ohm impedance since the connection has 2 ohms.

Once you have successfully located an amplifier that matches the impedance and RMS watt of your subwoofer, the next step simply requires you to connect the subwoofer to the amplifier and connect it to the car stereo.

An awesome powered subwoofer can drastically increase the performance of your car’s audio system, allowing you to make the best out of your commute home.

RMS Watts

Typically, subwoofers feature two-power handling specifications. RMS watts, also commonly known as continuous power handling, peak power handling or peak watts.

The Root Mean Square (RMS) wattage of the subwoofer depicts the amount of power the device can handle on a regular basis. The peak wattage specifies the maximum amount of power the subwoofer can withstand for brief periods without experiencing damage. In order to get the best quality sound, you need to match the RMS watts of the subwoofer to that of the amplifier.

Most power amplifiers in the market mention a list of RMS watt ranges. This range specifies the minimum and maximum power range that the device is capable of producing.

Once you are aware of the amplifier’s wattage range, you must ensure the minimum power is at least 75% of the subwoofer’s RMS watts and maximum 150% of the RMS watts.

If you ever have trouble deciding between the two, keep in mind that an overpowered subwoofer is a much better option than an underpowered one.

For every additional subwoofer you wish to install in your car’s audio system, the power amplifier’s wattage range has to be a reflection of the additional sub’s RMS watts.

For example, if you are installing 2 subwoofers of 300 RMS watts ratings, you must opt for a power amplifier that offers a power range between 450 – 900 watts. Or less, both the subwoofers will only get half the power its needs to operate efficiently.

Similarly, if you wish to add more than several subwoofers to your car’s audio system, you must upgrade the power amplifier as well.


Combining a subwoofer and amplifier for maximum results for your car’s audio system can only be achieved once you are able to match the basic components. While the best subwoofers and amplifiers can be bought as complete sets, many people often choose to buy them separately.

This is where the person must take the specifications of the subwoofer and the amplifier into account so that both the devices combine to produce excellent results.

A high-end amplifier works by strengthening the sound signals of a subwoofer. When investing in a subwoofer, consider its sensitivity and frequency response.

The power handling capabilities and the impedance of the amplifier and the subwoofer should be as closely matched as much as possible if you wish to listen to sound that is loud and clear.

Additionally, closely matching the subwoofer and amplifier keeps the devices safe, reducing the risk of overheating.