It is difficult to design a single speaker that covers the complete range of the human hearing. Possible but expensive. So a combination of units are normaly used to reproduce the desired sound range and a crossover is needed to separate the octaves that are to be send to this or that unit.

But crossover adds distortion (back to this nasty bit later) and being that we hear much better in the 1000 to 5000 Hz (vibration per seconds) range just where a 2 way speaker system would have it, some designers went to a three way (or more) system. Not only will you have a tweeter to reproduce the higher sounds better, you will have a woofer for the lows and maybe a mid (we older folks may remember the term "squawker") for...well, the mids.

So where does a "sub woofer" comes from? Well as the name state, it lives below the woofer. You can not have a subwoofer if you are without a woofer to begin with.

Now, not only do we have a number of distortions created by the crossover, we have more problems matching the various speakers sound qualities, keeping to sound waves emited by each units in sink with each others and dealing with more vibrations coming from the box that contain all of the above.

This is where the "art" of building a truly great speaker system begins. Do I use a single unit and avoid the crossover's nasty distortions? Keep to a two way and have a simplier crossover? Go for a three way and avoid the area where our ear hears the best? Have a big box that may extend the low notes? Keep it small to minimize vibrations generated by the box? What is best?

Have fun finding the best speaker for your listening needs.

Doc Sage