On 8/31/2013 7:23 PM, Larry Banks wrote:
Then, adding an inverse response in series with the total speaker
response -- the equalizer -- created what is known as a quasi-linear
system.
There's a HUGE problem with all of this analysis -- the loudspeaker
response is the sum of all of the drivers, with the directivity of each
driver superimposed, as well as the acoustic time of flight from each
to each observer. AND the response at every point is the COMPLEX sum
(magnitude and phase) of all of those drivers, and because the TIME is
different to each observer, which means phase shift that increases
linearly with frequency, AND is different to each observer. This means
that every observer hears DIFFERENT peaks and dips in the response. In
the pro audio world, we call these peaks and dips caused by cancellation
of multiple arrivals "comb filtering," because the amplitude response
looks like the teeth of a comb held vertically.
SO -- in the real world, with a gargantuan equalizer, you might
theoretically obtain a flat response for one point in space, but you
would be creating a worse mess everywhere else. :)
Bose speaker systems do include equalizers, but they are compensating
for the overall response of the system, not for the comb filtering
produced by the multiple drivers.
73, Jim Brown K9YC (Retired from pro audio)
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