Way down under

Yesterday I mentioned we'd jump into subwoofers as a series. Several of you suggested I start the series with a few explanations. Great idea. First question. What is a subwoofer? The answer lies in its name; sub - woofer. It is a woofer producing music below the lowest notes of your loudspeaker pair's main woofer. Second question. Why do I need one? There are two answers to this often asked question. First, there are few loudspeaker pairs that actually produce bass down into the lowest areas of music. For example, a pipe organ can produce frequencies well below 20Hz and there are few, if any, loudspeakers that actually produce music down to 20Hz, let alone below that frequency. This statement is controversial. In fact, if you want to start an argument tell an Audiophile his speakers don't really produce low bass in the room. I've had more angry looks by saying this than presenting my religious and political views. It's a hot potato. But here's the deal. When you read the specs of your favorite speaker pair it may tell you they go down to 20Hz (or whatever). If you look closely at these specs they should also tell you how they measured that response. Typically a measurement microphone is placed one meter away from the speaker. So, if you were to sit one meter away from your speaker you'd be able to get the bass that's advertised. Most of us sit a bit further back in the room. Second, where you place your main loudspeaker pair is probably not the best place in the room for producing bass. Typically it is not. Separating the duties of the main loudspeaker pair has advantages. You setup your speakers where they image best, you add the subwoofer where it produces bass best (and I'll tell you how to find that place in a later post). Third question. What's the best subwoofer type to get? You know what they say about opinions and everyone having one? This subject's no different. And while I won't attempt an answer here, I would suggest it's a deep subject. Of the various types of subwoofers that abound: ported, sealed, servo, open baffle, multiple drivers, large drivers, small drivers, paper cones, metal cones and plastic cones. Each has many different executions within those categories; some better than others. That's enough for today. Tomorrow we soldier on.