measurement

The “Bass Management Boot Camp” article about subwoofer setup that I wrote for the November S+V inspired an in-turn inspiring e-mail from reader Bruce Erwin. Bruce recalled his days setting up sound systems when he’d use a 1.5-volt battery to test subwoofer phase. If the sub and main speakers were in phase, he’d hear a single thump when he connected the battery to the wires leading to the sub's terminals. If they were out of phase, he’d hear a double thump.

That’s with passive subwoofers, though. Almost all of today’s subs have built-in amps, so this method wouldn’t quite work with them. Still, it got me wondering if I could come up with a simpler phase check than the ones I suggested in the article, which required either measurement or careful listening. My e-mail convo with Bruce gave me some ideas and, ultimately, a method that’s simpler than my original. And all you need to do it is a piece of free software and a meter you’ve either already got or can get for nothing.

I often worry that people get the wrong idea when I praise a speaker for sounding “flat.” By this I mean its frequency response is flat, which is a good thing. But if you ask the man on the street, I bet he’d equate flat sound with lifeless sound.

It’s high time I explained what frequency response is and why flat frequency response is desirable in audio products. Not only will I explain why non-flat response is bad, I’ll demonstrate it to you with some audio files I cooked up just for this article.

The way the audio industry has been measuring subwoofers for decades has turned out to be inadequate. But the new method they’ve come up with may be causing as much confusion as the old one.

We all know what distortion sounds like. We’ve heard it in heavy metal tunes, cheap iPod docks and the crummy speakers at Taco Bell drive-thrus. And we’ve all read distortion specs on things like receivers and subwoofers. But other than a general understanding that distortion isn’t something we want in home audio gear, most people really don’t know what it is.