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What exactly is the use of a subwoofer?

You would have seen a subwoofer for sure. A box that is attached to the soundbar or speakers or a home theatre system. Subwoofer for home is becoming very common now. But you may not know what is the use of a subwoofer. In this post, we are going to see the same.

what is the use of a subwoofer?
Pic courtesy: Rythmik subwoofers

What is a subwoofer?

What does a subwoofer do?

A subwoofer is a special kind of speaker with an enclosure that is often paired with a music system to produce bass notes. 

As you may know, humans can hear sounds between 20 Hz to 20,000 Hz. This depends upon the age of humans. Higher the age, less the high frequency they hear. Our concern is around the bass end. Especially from 1hz to 80Hz. This is where the subwoofer comes in to play. Below 20 Hz, you cannot hear the bass but you can feel it in your body.

The subwoofer has huge drivers compared to the tiny speakers of satellite enclosures. The size differs from 5-inch diameter to 21-inch diameter and perhaps even more.

You see, as the frequency goes down in the chart, the wavelength gets bigger and bigger. In order to produce low frequencies, the driver has to be big enough or smaller drivers with a high excursion. This speaker is coupled with high power amplifier so that the large drivers can move forward and backward faster to produce accurate bass notes.

Subwoofer vs speakers

closed up photography of brown wooden framed sony speaker
Photo by Anthony on

Subwoofers are a kind of speakers in general. The difference is that subwoofers do duties on the lower end of the spectrum. Speakers have identical components of a subwoofer but the frequencies it produces are different. Structurally, subwoofers have bigger magnets, strong speaker cones, and huge voice coils ( sometimes there are two or more coils for more power and efficiency) and they weigh a lot. Comparatively, speakers have small magnets, small voice coils, less rigid cones, etc which are good enough to produce higher frequencies above 80Hz effortlessly.

What is the use of a subwoofer?

Why a subwoofer is needed?

The subwoofer is needed because traditional speakers seldom hit very low. Some speakers are full range and go low but not as much as a subwoofer. 

Below 80Hz, the sound is omnidirectional meaning your ears cannot determine the direction of the sound. This means no matter where you keep the subwoofer, you can hear the bass but you cannot say where it is coming from. Subwoofers make the music system small and simple to keep it in the house. If there isn’t a subwoofer and you need bass, the only way to go is to build a very big enclosure and putting in a big speaker to produce bass.

some subwoofers are specialised in the mid-bass. And some go ultra-low. But, you do get costly subwoofers that do both. The subwoofers that are great in the mid-bass segment can give a lot of punch and drive. It hits your chest and resonates with your body. You feel the bass. The subwoofer that goes ultra-low under 20Hz can give you an eerie feeling that the subwoofers tuned to mid-bass lack. Ideally, the subwoofer that excels in both gives you the best movie experience.

How does a subwoofer work?

There are two types of subwoofers. 

  • Sealed subwoofers
  • Ported subwoofers

The sealed subwoofer is a little compact in nature. When the speaker moves forward, the air in front is pushed when the speaker cone moves back the air gets relaxed. This makes a pattern of the wave which we call bass. In ported subwoofer, things are less different.

As the name suggests, ported subs have a port. To accommodate the speakers and ports, the subwoofer has to be big. It is sometimes tough to find a space for subwoofers in the living room. In this case of a ported subwoofer, when the cone moves forward, the air is compressed. When the cone comes back and goes invert, the air is relaxed. However, the rear waves from the back of the woofer are also fed to the front by a port which time aligns frequencies so that you will get significantly more performance compared to a sealed subwoofer.

Where to place a subwoofer?

Subwoofer placement is very important. Because a small change in subwoofer placement can have a significant change in bass and its tonality. There is no hard and fast rule on where to place a subwoofer. But the best placement can be found by a small experiment.

Place the subwoofer on the seat where you sit and watch movies or listen to music, now crawl around the room and find a nice spot where the subwoofer sounds great. Put your subwoofer in that spot and you are done. This place will be the best place to put the subwoofer in your room. Even the best subwoofer sounds bad in a not-so-good place.

Adding two subwoofers can even out the peaks caused by room modes.

Is a subwoofer necessary for TV?

You can connect the subwoofer to a TV but it is not ideal. It is best to use a subwoofer with a speaker system or a home theatre system. This way you not only integrate the sub to your music system but also you get the sound quality overall very good. This is because the TV’s have mediocre sound quality in general.


The subwoofer can be said as an add-on for music and movies but quite literally, it is one of the main components of any sound system. With movies like john wick, avatar, Jurassic park, you crave a proper subwoofer. Without a subwoofer, you will just miss a big part of a movie or a piece of music.

2 thoughts on “What exactly is the use of a subwoofer?”

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