Here's a problem that has enjoyed almost no discussion in
speaker design circles because there has just not been a
Woofers that work well in the low bass do poorly in the upper
bass and vice-versa. This is because the long stroke and
heavy moving system needed for the lows prevents the quick
articulation needed to closely track the signal in the upper
bass. And the nimble driver capable of portraying texture and
rasp won’t do grunt work. There is a ten times difference
between 20 and 200 cycles so it should not come as a
surprise that one driver won't really cover the territory.
So you need two kinds of woofers. No problem, right? Just divide the bass into two bands. Simple right? No, not
simple because low frequency passive filters (crossovers) just flat out suck. The huge capacitors and inductors
needed to function at those frequencies are not only expensive but add so much impedance that they destroy the
amplifier’s ability to control the woofer. And the timing errors really add up. The low bass ends up tubby and
slow, the upper bass gets smeared and the two don't really want to meet in the middle and become one.
The cure is worse than the disease. We've all tried it and we've all come up short. The best we've done is to let the
woofer work naturally, then try to "graft" a subwoofer onto it from below. This is far from an optimization.
Sometimes it’s pretty good.....but never superb.
So, as speaker makers we've just gotten used to it. We've adjusted our expectations of what great bass sounds
like down to this limitation.
But now that's over.
Now we can easily divide the bass into two bands in the data stream with our Digital Signal Processor. We’re free
to use drivers specialized for their tasks. Then we can adjust every aspect of the signal before we send it to the
amps. We can readily create a unified presentation. Each woofer is directly connected to its amp so they all go
whack, whack, whack! And easy room equalization comes along for the ride. Problems gone. Killer low bass, killer
mid bass, killer upper bass. Killer bass!
A New Frontier in Audio: Dual Band Bass
Issue #1 - Dual Band Bass
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