What is a Subwoofer: Breaking Down the Basics

Restore the crucial bottom 2 octaves & you release everything above it


My name is John Hunter and I own a company called REL Acoustics and some friends thought it would be useful to explain to those of you who are not as experienced, what exactly a subwoofer is. For theater, It’s utterly critical. If you don’t have a subwoofer, you’re not listening to theater. And full stop that’s it. It absolutely is the element that adds all the drama, all the excitement, all of the fun stuff of movies.


Interestingly, for music it adds an entire different dimension to things. There’s richness and warmth and beauty that exists in your system that a subwoofer can unlock.

So, what are these three basic building blocks that are used to build really any subwoofer, pretty basic things.

I’ve got a small one here. I’m just going to borrow it for a moment. What we have here is the driver, the actual element that pistons in and out and produces bass. We have the amplifier, which is used to actually drive that.


Now, relax, we’re not stealing power from your amplifier. We’re actually just taking a small signal and then we’re using this amplifier to make that signal much louder. Then any driver requires a cabinet.

Now let’s jump in and ask, why do we need this? I have some nice speakers. Isn’t that sufficient? And the answer is not for deep bass. The amount of power that’s required, electrical power, that’s required to produce really deep bass that actually can keep up with your main speaker is vastly more.


So, you may have an inexpensive receiver. Let’s say that it puts out a hundred Watts per channel. We may well need two, three, 400 Watts per channel in a subwoofer, that’s this small, in order to make bass that really leaps into a room and takes over and gives you that deep, really satisfying base that you’re after.

So, what impact does a subwoofer have on music and movies. Let’s start with the easy one. All of the things that are the special effects in movies.


Whether it’s a submarine, you know being depth charged, a spaceship getting hit by a photon torpedo all of those actually go out through a very special dedicated channel.

It doesn’t matter if it’s an old-style DVD or Blu-ray. Even Netflix has found a way to get all of this stuff onto your system. There’s a special channel, it plugs in with its own little connector from your receiver or your soundbar, out to this, and it literally reproduces those special effects.


It’s called an LFE, which is short for low frequency effects. The part that is a little harder to understand and much harder to do is actually connecting up and restoring the low bass that we’re used to hearing in music. Even if you’re somebody who loves acoustic music exclusively, or you like chamber music in classical, all sound that you’re used to hearing is what is referred to as full range. Now just a quick physics lesson.


Full range means all the way down to zero and all the way out to infinity. And when you consider that, now, granted, as you start getting down into the low, low frequencies, and into the very, very highs, everything begins to fall off in level. But we’re used to hearing that, right?

Our brains are used to processing things. So, you’re hearing things in a recording for example, and you’re not aware of it like the air conditioning running in the background, in the studio. And how does it sound? It sounds like nothing. You don’t think about it. It’s just there. When it’s not there, you start to have all kinds of little signals that you’re listening to a stereo system, not real music.


And as you get into this a little bit more, it doesn’t have to be super expensive. You’ll find that the restoration of those cues of the ability to hear somebody’s footsteps echoing down a hallway. To hear somebody, for example, live on stage, who’s playing the guitar tapping their foot on the stage and it comes back up to the microphone stand and ultimately onto the piece. When you hear that restored, it’s like seeing a beautiful painting restored, it was dull and faded and all of a sudden, you’re going oh my gosh.


And that’s what our company is dedicated to. We’ve worked so hard to restore those bottom perhaps, two octaves. Where all the magic occurs, because if you get that magic perfect, it just releases the upper eight octaves of music. So, everything is affected holistically. It’s not one thing it’s not for those who just want a big, huge boomy sound.

You can do that with almost anybody subwoofer, but the really difficult thing in music is getting a subwoofer to blend perfectly with your main speakers. And then it just takes over and blooms and everything comes to life in a way it never has before.

November 11, 2020 - Posted in: Sound Insights, Videos