[TowerTalk] Bose 901 antenna theory

[Jim Brown]

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)