Here's a problem that has enjoyed almost no
discussion in speaker design circles because there
has just not been a good solution:
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
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
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!
Issue #1 - Dual Band Bass
A New Frontier in Audio: Dual Band Bass
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