How to Combine an Amp and Subwoofer for Maximum Results

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How to Combine an Amp and Subwoofer for Maximum Results

Both the amplifier and the subwoofer are integral parts of good sound systems. An amplifier strengthens the sound signal and increases the volume. The subwoofer is a type of speaker responsible for reproducing the lowest bass sounds. At home, they are used mainly as a part of a home theatre or hi-fi system in order to playback the sounds of films and music. However, they may also be included in a car sound system. In all cases, they are usually combined with other speakers. If speakers are sold as a set, then an amplifier and subwoofer should be included. However, each component can be bought separately. The first thing to consider when combining an amp and subwoofer for maximum results are their features. Then decide how many subwoofers are required. Amps and subwoofers are available in electronics shops, but the widest selection is found online on large sites, such as eBay.

Features of Amplifiers and Subwoofers

Amplifiers and subwoofers that are used for different systems, such as a home theatre or a car sound system, can vary slightly in their features because they serve different purposes. However, there are some common specifications that all amplifiers and subwoofers share. Features to consider include, size, frequency response, sensitivity, and impedance.

Size of Subwoofers

When it comes to subwoofers, their size can play a significant role in the way that they sound. Larger subwoofers are able to reproduce more bass sounds than smaller ones. The size refers to both the subwoofer itself and the cabinet that surrounds it. For best results, both the cabinet and the subwoofer should be as large as is acceptable for the space. The room and the subwoofer size are closely correlated. In general, larger subwoofers reproduce more sound, but their efficiency also depends on the amplifier. For larger rooms, a big subwoofer and a more powerful amplifier should be used.

Frequency Response of Subwoofers

The frequency response refers to the range of frequencies that speakers can reproduce. The human hearing range is 20 to 20,000 Hertz (Hz), with lower numbers representing lower bass sound. For a subwoofer, the lower number is important and it should be quite small for a subwoofer to provide deep bass sound.

Sensitivity of Subwoofers

The subwoofer's sensitivity refers to its efficiency. The sensitivity is measured in decibels (dB) by placing a microphone about 1 metre from the subwoofer and then playing a sound of 1 watt through it. The average sensitivity is around 88 dB, while 90 dB belongs to the higher sensitivity range. Subwoofers with a sensitivity of 95 dB are considered very sensitive. Sensitive subwoofers convert power into sound more efficiently. If the subwoofer is not sensitive enough, then it requires a more powerful amplifier for maximum results. A subwoofer with higher sensitivity uses less power and can be combined with a less powerful amplifier.

Impedance of Subwoofers and Amps

The impedance reflects the subwoofer or amplifier's resistance to power. Commonly, the impedance is rated at 8 Ohms, although the impedance varies with the frequency. Although many high end speakers have an impedance of 4 or 6 Ohms, some amplifiers cannot handle speakers with an impedance lower than 8 Ohms. The amplifiers may work initially, but may fail after being used for a long period of time.

Power Handling of Subwoofers and Amps

The power handling specification refers to how much power the subwoofer or amplifier can handle. However, the power handling ratings only provide a little bit of information about the way that the subwoofer sounds. More power does not necessarily mean more volume because sensitivity also plays a role. A subwoofer is better when combined with an amplifier that offers more power. There is no need to worry that more powerful amplifiers may ruin the subwoofer. In fact, speakers are more frequently broken by underpowered amplifiers.

Amplifiers have separate output channels for each speaker and the power for each one of them is important. For amplifiers, the power rating is measured in watts per channel. For home audio systems, the average rating is somewhere between 20 and 200 watts per channel. When comparing the power ratings of different amplifiers, it is necessary to detect the impedance and frequency response at which it was measured. If these values are different, the power ratings are not comparable.

Voice Coils for Subwoofers

If the amp and subwoofer are to be used in a car sound system, then it is necessary to consider voice coils. Voice coils are the terminals inside the subwoofer. They are responsible for driving the signal in a subwoofer. Car subwoofers have either one or two voice coils. Dual voice coil models have more wiring options. They are usually also designed to handle more power and offer better performance.

Amps and Subwoofers for a Home Audio System

Most amplifiers and subwoofers that are designed for home use are compatible with each other, so they can be combined easily. However, the best sound quality is achieved by considering their specifications.

Matching Impedance for Amps and Subwoofers

The amplifier itself does not have an output impedance value; it is the subwoofer whose impedance value should be considered. Amplifiers usually have an impedance range that they support. Many modern amplifiers may have a customisable impedance setting that allows the listener to tell the amplifier what kind of subwoofer is connected to it.

Subwoofers with a low impedance of about 4 Ohms can put too much of a strain on the amplifier because lower impedance allows more current to flow and the amplifier needs to deliver more power to the subwoofer. This is the case if the amplifier is not designed to support low impedances. Subwoofers with lower impedance are usually high end and have a wider dynamic range. They can also be used for higher volumes than subwoofers with higher impedance.

Matching Power Ratings for Amps and Subwoofers

In order to match the power ratings of the amplifier and subwoofer, the buyer should consider the watts per channel value. The subwoofer does not output power, but receives it from the amplifier. Sometimes subwoofers have a minimum power value which represents the amount of power required in order to get any sound out of them. The amplifier needs to provide at least that much power. Usually this rating should not pose any problems because amplifiers are sufficiently powerful. The maximum power rating is considered to be more important. The maximum power input determines how powerful an amplifier can be when connected to the subwoofer. This value is often conservative and exceeding it by a small amount does not usually cause a problem, but care should be taken in order not to overheat the audio system. However, if the subwoofer is not used at a high volume, more powerful amplifiers should be fine.

Number of Subwoofers

While the home audio system usually has one subwoofer, there might be more than one in a car sound system. This results in the best bass sound for the vehicle. The following table compares the common subwoofer combinations, outlining their advantages and listing the type of amplifier that suits them best.

Subwoofer Combination


Best Amplifier

One 4 Ohm single voice coil




Two channel

One 4 Ohm dual voice coil

Two ways of installing


Great power handling


Two 4 Ohm single voice coil

Lots of bass


Two 4 Ohm dual coil

Wiring flexibility

Lots of bass

Two channel

As the table shows, the amplifiers can be either mono or two channel. Two channel amplifiers usually work best at lower impedance values, such as 4 Ohms, while mono amplifiers provide the most power at around 2 Ohms.

Buying Amps and Subwoofers on eBay

When buying your amplifier and subwoofer on eBay, try to look for items that are best suited to a particular environment. Home audio and car sound systems use different speakers and amplifiers because these environments are different. Home audio subwoofers are usually enclosed cabinets, while car subwoofers may require some wiring. Therefore, start your search by typing in "car subwoofer" or "home amplifier". If you already have one of the components, either the amplifier or the subwoofer, then bear in mind the specification the existing item so that a compatible device can be found. You should match their impedances and power ratings for maximum results.

If you have any questions about the amplifier or subwoofer then contact the seller by using the "Ask a question" link.


Combining an amp and subwoofer for maximum results for a home audio or car sound system is done by matching the basic components. Although amplifiers and subwoofers can be bought as complete sets, buyers often opt for buying them separately. This is where the specifications of the amplifiers and subwoofers should be taken into account carefully so that the devices can be combined successfully.

A powerful amplifier helps to strengthen the sound signals of a subwoofer. When choosing a subwoofer, its frequency response and sensitivity should be considered. The impedance and power handling of the subwoofer and the amplifier should be matched as closely as possible because this delivers clear and loud sound, which keeps that devices safe because they do not overheat. A convenient way to shop for subwoofers and amplifiers is online at eBay, which allows buyers to make informed choices so that they can combine the devices for maximum results.

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