How to Buy Speaker Parts for a Subwoofer

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How to Buy Speaker Parts for a Subwoofer

A subwoofer is a common component found within high fidelity audio speakers, where it assists in the reproduction of bass sounds. Although a subwoofer is not strictly essential for the production of high quality sound, it does allow speakers to be more compact and use less power, without compromising their low frequency sound reproduction. Common in home theatre setups and stereo music applications, their popularity extends beyond home audio, with subwoofers being incorporated into many in-car stereo systems. They are also found in some personal computers systems, especially those designed for gaming.

There are many people who prefer to install their own subwoofer, rather than buying a ready-manufactured audio component. One obstacle to this is knowing which speaker parts are required. A second obstacle is knowing where best to acquire them. Before attempting to install a subwoofer, it is therefore important to understand a little about the types of speaker parts available. This includes knowing the differences between sealed and ported subwoofers, as well as how to choose the size of the driver.

Speaker parts for a subwoofer are too specialised to be widely available on the high street, and most people searching for them these days would look online. However, even online, specialist audio component retailers can be expensive. For those looking to save money on their purchase, it is often possible to find subwoofer components at eBay, at sensible prices. Which makes eBay the ideal place to start searching for subwoofer parts.

The Parts Required for a Subwoofer

Although important to the reproduction of good quality sound, subwoofers are not actually that complicated to build. The main speaker parts, other than the casing that houses the subwoofer, include a drive unit and an amplifier. In addition, some form of damping material is needed, which ideally should be acoustic foam. However, since acoustic foam is expensive, there are other materials that can be used instead. Beyond these items, less specialised parts include speaker terminals, cabling, and some fabric.

The Speaker Casing

Before buying any parts, it is important first to decide on the design that is going to be executed. This determines the precise parts required. Although other options also exist, there are two main categories of subwoofer: sealed or ported subwoofers. The difference between the two depends on the construction of the casing.

Sealed Subwoofers

A sealed subwoofer is one in which the driver is mounted within a casing that is completely sealed. Ideally it should be airtight. Having a sealed case is an important because it affects the way in which the subwoofer works, and therefore affects the choice of parts. By sealing the driver within an airtight container, the amount of power needed to operate it increases. This is due to resistance from the air pressure that builds up when the driver moves back and forth.

Ported Subwoofers

The alternative to a sealed subwoofer is one in which there is a port to allow air to enter and leave the casing. This reduces the air pressure pushing against the driver, thereby reducing the power consumption. For a given level of volume, a ported subwoofer is therefore more power efficient.

Advantages and Disadvantages of Sealed and Ported Subwoofers

Power consumption is not the only thing to consider when choosing between a sealed or ported design. The two advantages of a sealed subwoofer is that it can be made smaller, and it is generally accepted that the sound quality is better.

Size can be an important consideration. For a ported subwoofer, which operates at low frequencies, the size of the case would need to be fairly substantial. Not all rooms would be able to accommodate the large housing required, therefore in deciding which type of subwoofer to build, the available space should be taken into consideration. 

The Driver

Having decided on whether the subwoofer is going to be a ported or sealed subwoofer, the next decision is to address is the size of the driver required. Before doing this, the buyer needs to understand a little about the sound ratings which apply to low frequency sound reproduction. Sounds are rated in frequencies, with 20 Hz being the lowest frequency most people can hear, and 200 Hz being the highest frequency that a subwoofer would be expected to handle.

Infrasonic Sound

Sounds below 20 Hz are called infrasonic sounds. Although people cannot hear infrasonic sounds, they can feel sounds at this frequency. Many subwoofers are designed to accommodate such low frequencies, with 15 Hz considered a good frequency to aim at when building a subwoofer.

Frequency and Size

It is these very low frequencies that are responsible for the ground-shaking thumping which some people like and others hate, so to some extent the frequency is a matter of personal preference. It needs to be borne in mind, however, that the lower frequency, the larger the housing for the subwoofer. Also, one should know that the production of infrasonic sound requires a lot of power.

Driver Size

Having decided on the frequencies, it is now possible to choose the driver size. Driver size varies greatly, depending on what the subwoofer is expected to do. For domestic use, in a living room, the size might typically be from 25 cm to 50 cm. There is not a significant difference in cost between a large and small driver. However, it is important also to factor in the extra cost of a larger casing for a larger driver, and the extra space that a larger housing requires. A 40 cm or 50 cm driver would require a very large housing indeed, and may well be impractical for many sized rooms.

Bigger is Probably Better

That said, since a larger driver allows the subwoofer to handle low sounds and high volume better, with less risk of distortion. It obviously makes sense to buy the largest driver that is consistent with available space and resources.

The Amplifier

Most subwoofers are ‘active’ subwoofers, in that they incorporate their own amplifier. Alternatively, it is possible to build a ‘passive’ subwoofer, which relies on an external amplifier. If an equaliser is in setup, the question of choosing an amplifier can be complex. But for a normal, home-built subwoofer, as long as there is a decent amplifier, an equaliser is not essential.

Plate Amplifier

For a ported subwoofer, a plate amplifier is often a good choice. These can be built directly into the enclosure. A plated amplifier does not need a fan and is very quiet.

Standalone Amplifier

For a sealed subwoofer, it is necessary to use an external amplifier. If there are going to be several subwoofers running together, it is possible to buy one standalone amplifier to share among them.

Where to Buy Speaker Parts for a Subwoofer

Buying the parts needed to build a subwoofer can be challenging, as these are not items commonly found in typical high street retail outlets.They are simply too specialised to achieve the volume of sales needed to make it worthwhile for shops to stock them. This leaves a relatively small number of specialist electronic component retailers as the only source for those shoppers who are confined to the high street. Often, these retailers charge prices which reflect the lack of competition. For shoppers who are able to shop online, however, a better option is to visit eBay , where speaker parts for a subwoofer are easier to find and at better prices than what’s available on the high street.


Subwoofers are used to increase the bass sound on high fidelity audio systems, without needing to use a large amount of extra power, or requiring that the speaker be excessively large. Subwoofers are found in car audio as well as home audio applications, such as home theatre and gaming. Although most subwoofers are supplied commercially, they are relatively easy to construct as part of a DIY project. The casing for a subwoofer is generally either ported or sealed. Each type has its advantages, with sealed units being smaller, but ported units using less power.

When buying the parts needed to build a subwoofer, shopping in the high street is unlikely to be rewarding. Subwoofer parts are too specialised to be widely stocked, and for those shops which do sell them, prices are often high. Online retailers such as eBay do not suffer from the stocking constraints which affect the high street shops, and can therefore offer a better range at keener prices. This makes eBay a convenient and attractive venue for buying speaker parts for a subwoofer.

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