What Is a Subwoofer?

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What Is a Subwoofer?

Almost everybody loves music, and to play good quality music, one needs a good audio system. Modern audio equipment has come a long way and even a basic audio set can play high quality music with clear high notes and impressive sounding bass. One important component of a good audio system is the subwoofer. In the past, those who wanted powerful sounding speakers had to get large, expensive speakers which took up a lot of space. A subwoofer is a dedicated speaker capable of producing powerful low-frequency sounds known as bass. Plus, present day subwoofers often do not require a lot of space and can be visually pleasing as well because they come in range of designs.

Buyers who wish to know more about subwoofers should know about the structure and types of subwoofers, as well as the main features to consider when purchasing such as device, including from eBay, in order to make a wise purchase.

Getting to Know a Subwoofer

A subwoofer is a loudspeaker that only produces low-frequency sound, also known as bass. Bass sounds are usually sounds that range from frequencies of 20Hz (Hertz) to 150Hz. Subwoofers are specialised speakers and do not produce midrange- or high-frequency sounds. Therefore, they are often paired up with other speakers to form a complete speaker set capable of producing sounds of all frequencies.

Although most main speaker systems have an amplifier, some subwoofers have their own power amplifier unit. This enables a subwoofer to create deep, clear bass, without taking any power from the main amplifier and burdening it. A high quality subwoofer always has its own amplifier, which allows the main amplifier or receiver to focus more on reproducing cleaner midrange sounds. Thus, the amplifier and main speakers are able to function efficiently and produce notes with less distortion. This means that sounds from instruments or voices in a movie become much more clear, while rich bass notes are still reproduced.

Structure and Construction of a Subwoofer

A subwoofer can be made of many different materials, and these materials influence the quality of the subwoofer. Some of the materials used in making the subwoofer’s diaphragm are reinforced paper, carbon, plastic, and aluminium. The diaphragm is the outer covering of the speaker, which vibrates when it plays any audio. The enclosure or box of the subwoofer is the frame holding all the parts of the speaker. It is often made of cast or stamped metal, with cast metal ones being more rigid, and stamped ones being more prone to cause sound distortions. A subwoofer enclosure has a hollow space inside of it which allows the speaker inside to vibrate and produce powerful sounds.

Subwoofer boxes come in many different sizes and types, with different types offering different sound quality and volume. Therefore, it is important for one to select the right type of subwoofer when buying it as an addition to the home or car audio system. Other components of a subwoofer are the voice coil, which moves the diaphragm to produce sounds, and the suspension, which holds the diaphragm in place. Although the suspension holds the diaphragm, it still allows it to move to a certain degree, which contributes to sound production.

Why Buy a Subwoofer?

The main purpose of a subwoofer is to produce low-frequency bass, and deep bass is important whether one is listening to music or watching a movie. A good quality subwoofer that produces an impressive bass is able to add more emotion and excitement to a good movie or music, which enables one to fully immerse in the movie and music.

A subwoofer can also solve problems regarding speaker placement. Often times, when there is no subwoofer, it is difficult to find a good location for the main speaker for it to best project clear mid- and high-frequency audio, besides providing good bass for listeners. With a separate subwoofer, the main speaker can be placed in a location that provides the best audio, while the subwoofer can be placed in another location where it can produce the best sounding bass.

High quality subwoofers can also greatly reduce the burden on the main speaker with a subwoofer in the system, since the main speaker does not need to produce bass. When bass is produced, there is a big cone movement in the speaker. A main speaker that has to produce bass can be very taxed, and this results in audio distortions. With a good subwoofer, an audio system can reproduce all sound ranges at high quality, thus providing for a better enjoyment when one is watching a movie or listening to music.

How to Purchase a Subwoofer

Buying a subwoofer is an important decision especially if one enjoys good quality audio entertainment. One can purchase a subwoofer as an addition to their existing home audio system or for their car. Some of the things one should consider when buying a subwoofer are its type (active or passive), size, enclosure, and power rating.

Active or Passive Subwoofer

Active (powered) subwoofers require a separate power supply, while passive ones do not. A passive subwoofer gets its power directly from the amplifier or receiver of the main system. Therefore, the sound produced on a passive subwoofer depends on the capacity of main amplifier or receiver. An active subwoofer, on the other hand, has a built-in amplifier which provides power to the subwoofer. This enables the subwoofer to produce better audio, besides preventing the amplifier on the main system from getting too burdened.

The Size of Subwoofers

The size of a subwoofer is determined by the size of its drivers, which are measured in inches. Common driver sizes are 8 inch, 10 inch, 12 inch, 15 inch, and 18 inch. The 10 inch subwoofers are less common because many of them cost the same as a 12 inch subwoofer. The 12 inch subwoofer is the most common and is suitable to be used at home. It offers a lot of power and can provide good bass for a large room.

On the other hand, 15 inch subwoofers are powerful enough for a large hall and less suitable to be used at home. When deciding on the size of a subwoofer, one must take into consideration the size of the room that it will be used in. If one has a small room, it is sufficient to just buy an 8 inch subwoofer.

The Enclosure of Subwoofers

A sealed enclosure subwoofer is a speaker within a sealed box. In a sealed enclosure, the pressure from the speaker becomes trapped and acts as a spring to restrict the cone movement. A sealed enclosure subwoofer is often small and gives accurate bass. A ported enclosure has an additional opening for a port. This opening allows the energy from the rear and the front of the speaker to combine, and as an effect, doubles the cone area. This means that a ported enclosure subwoofer can produce more powerful bass than a sealed one. However, a ported enclosure subwoofer has less audio accuracy and takes up more space than a sealed enclosure subwoofer.

The Power Rating of Subwoofers

To accurately determine the power of a subwoofer, one should take note of its root means square (RMS) power rating, which is expressed in watts. Although the suitable power rating for a subwoofer depends on the user’s preferences and room size, a subwoofer with a power rating of 75 to 150 watts is usually good enough for a home theatre system. When buying a passive subwoofer, one should check that it can handle the power of the amplifier from the main system.

Purchasing a Subwoofer on eBay

eBay has a large selection of equipment meant for audio entertainment, including subwoofers. To search for a good quality subwoofer, you can start on the eBay home page and select the ‘Electronics’ and then ‘Sound and Vision’ category. All you need to do is to type the item that you are interested in into the search bar on the page. You can search for "subwoofer", or use more specific keywords such as "home theatre subwoofer". After using your keywords to search, eBay will provide you with a list of all related subwoofers for you to look at. Make sure you read the description and the price of each subwoofer before you select one.

After selecting a subwoofer, read all the relevant details about the item so you know what you are buying. You should look at the full item description, price, postage fee, and return policy. If you have any doubts about the product, you can contact the seller directly by clicking on their name. One eBay feature which can help you decide on your purchase is the seller feedback score. A seller with a higher feedback score has positive feedbacks from previous customers and has a good track record on eBay.


A good subwoofer can make any music or movie sound more powerful and exciting, which enables the user to fully enjoy their listening experience. Having a subwoofer also enables users to have a better setup for their home audio system since the main speakers can be strategically placed to produce clear, accurate audio imaging, while the subwoofer can be independently placed at a suitable location to provide the powerful bass.

When choosing a subwoofer, it is usually better to buy an active subwoofer, which has an independent amplifier or receiver, than a passive one. With an independent amplifier, the subwoofer can obtain enough power without burdening the amplifier on the main speaker system. When looking for a good subwoofer, there are various factors which should be considered, which are the size of the subwoofer, the enclosure type, the power rating, and whether the subwoofer is a passive or active subwoofer. Regardless of their subwoofer preference, buyers are likely to find the right one on eBay, which has a large selection of high quality subwoofers.

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