"Phil Allison" wrote in message

"Arny Krueger"

Now for the seriously damning facts about the Bose 901. When the 901
was built, not that much was generally known about optimizing the
performance of arrays of small drivers. It turns out that arrays of
small drivers can be
a
real can of worms, if smooth, well-balanced frequency response is
desired. I'm quite sure that if Bose were to design the 901 today
with a clean
piece
of paper, they'd do it quite a bit differently.


** What - you mean there is an even " cheaper " way than the
one used now ;-)


Probably the most serious problem with designs based on ad-hoc
collections of identical small drivers is that they can have very
rough frequency response (lobing and comb-filter effects) when you
move slightly off-axis, and they can also have frequency response
that is a strong function of distance from the speaker to the
listener. There are ways to manage these problems with generally
involve putting the drivers on curved baffles, and/or adjusting the
level and/or frequency response of the drive to the various drivers.
However, the classic Bose 901 design really does neither of these
things well.

Here's an AES paper that points out these problems and potential
solutions in some detail:

Author(s): Keele, Jr., D. B.
Publication: JAES Volume 38 Number 10 pp. 723·748; October 1990
Abstract: The Bessel array is a configuration of five, seven,
or
nine
identical loudspeakers in an equal-spaced line array that provides
the
same
overall polar pattern as a single loudspeaker of the array

One important point is that the no way is the Bose 901 a
Bessel array. A second important point is that of all the Bessel
arrays analyzed, 5 drivers in a row was found to be the only one
that was recommended.


** Hang on Arny, what multi driver array has the 901 really got
?????

The answer is none. There is only ONE driver facing the listener.

You are mixing the 901 up with the 802 PA speaker.

Phil, what are those two arrays of 4 speakers on the back of the 901? Or, am
I imagining that I saw them there?