Why do I need a subwoofer?

What is a subwoofer?

What is a subwoofer exactly? The common notion is that it is a large square box with a large driver in the middle. And it’s big. Very big (did I just mention that again?).

The sole purpose of a subwoofer is to reproduce the deepest of bass and to take over the reproduction of this part of the sound stage. Your speakers are not supposed to play the deepest tones, as this makes it more than difficult to place them correctly.

For home use there's typically two types of subwoofers available. Sealed and ported subwoofers. Sealed subwoofers consist, as their name suggests, of a sealed cabinet and a the bass reflex subwoofer is very similar in looks, but it's usually a little large and has one or more holes (ports). As a general rule the sealed subwoofers are a little smaller than their ported brother, but can't play as loud. The bass reflex subwoofers are a little larger and can typically play a little louder.

Very often a subwoofer is a square box with a build in amplifier and a large loudspeaker (the driver). The bigger the box, amplifier and driver, the louder the subwoofer can play – in general.

In order to reproduce the deepest bass a lot of power is required from the amplifier, or a large membrane area is needed (a big speaker driver). If both is present it is just great.

Why do I need a subwoofer?

Everybody needs a subwoofer. Eventhougth you bought the biggest speakers available (nothing wrong with that by-the-way) you still need a subwoofer.
If you want deep and clean bass in abundance – and who doesn’t? – then you need to get yourself a subwoofer.

Do you enjoy feeling the kick drumm in your chest or when the cinema chair starts vibrating when a motorcycle passes by on the screen, or do you simply just want to generally improve the sound of your speakers? Then you will have a hard time getting around not buying a subwoofer, as the subwoofer is superior in reproducing of this part of the sound stage. More precisely it is the sound between 20Hz and 80Hz.

There’s only very few speakers that is capable of playing all the way down to 20Hz or even 30Hz for that matter. Those who do, will most likely not be doing that at the listening position as this requires a great deal of presicion when placing your speakers.

As discussed in an earllier blog post here, the real goal is to achive correct reproduction of the bass in the listening position and at the same time being able to deliver a serious (powerful) sound presure. This is where the subwoofer really shines. This is what it is made for. It can transform each hit on the kick drum into a hard punch in the chest (or a soft one if you turn down the volume) without having to comproise the interior of your living room.

Eventhough you are not looking for a hard punched in the chest, you should still get yourself a subwoofer. Why is that? Well, is all to do with the way we perceive sound. The deepest tones – i.e. the bass – have a huge impact on the rest of the sound stage. If the bass region is under control, then the rest of the sound stages will be impacted in a positive direction. If there, on the other hand, isn’t much control over the bass the total sound stage is impacted negatively.

One of the first things to be impacted by imperfections in the bass are the reproductions of voices. It quickly becomes hard to hear they are saying in the radio or to keep up with the dialog in a movie.

I cannot underline enough how important it is to have the best posible bass reproduction and this starts with a subwoofer.

Which subwoofer should I buy?

It’s all about your room. The bigger the room, the bigger the subwoofer you will need. In large rooms you can benefit from the higher output of ported subs and in smaller and medium sized rooms, sealed subwoofers works well (yes they are smaller). The sound reproduction is similar if not identical from these two types of subwoofers. When selecting a subwoofer it is all about how large your room. The bigger the room the more powerful subwoofer you need.

As a general rule you should not be looking for a subwoofer with a driver smaller than 10”. It is in fact a bit of a strecht to call that a subwoofer.

They main thing to worry about is how loud you would like to play. Many people believe they need to be able to play at full reference level. That is usually not needed and by-the-way also very very loud! Referene level is based around 85dB and have peaks all the way up to 105dB. That is a lot! If you hit 75dB in the listening position most people will be more than satisfied. At this sound presure you will be able to fill the kick drumm in your chest and your coach will shake.

A later blog post I will be touching on how you should place your subwoofer and you need to always have bass management activated.

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AUTHOR - Tue Dissing

Founding director of Lyd By Dissing and a passionated hifi and music lover, with a taste for good sound, wine and (not to forget) beers.