"Tom" wrote in message
oups.com
Hello all,
I was lucky enough to inherit a pair of 901 II in Tucson,
The 18 drivers are in perfect shape, and they look as if
they were recently refoamed, All 18 play approximately
the same as measured by the hose-in-the-ear stethoscope.
I wrote to Bose, and they answered the next day (see
below.) They said I must find a Series II EQ. Response
curves werethe same for I's and II's, different
thereafter. My II speakers are acoustic suspension --
sealed box expecting plenty of amplifier power to move
them and compress the air in the box, while smothering
backwaves. I am guessing they caved to the "no highs, no
lows; must be bose" cliche and ported their boxes to
shore up the base while stonewalling the boomy problems
bass reflex can bring. OK, I admit I am guessing on that,
but what else could those nifty tailpipes sticking out of
the reflector side be for?
Anyway I began looking for a used E in the Q II, but eBay
sellers don't know anything about complex electronic
hardware, so it's a crap shoot.
I want to use these speakers in the home I am building,
more specifcally in the great room (30'L x 20'w x 12' h.)
They were such an icon in my youth. I am not going to mod
the boxes; I will try the EQ, and will thoroughly tes
repositioning them. However, in looking at the EQ II,s
pics it would appear to control the audio curve just as
do ordinary bass and treble controls on my receiver; why
can't I use the latter and forget the
questionably-functioning 30-yr EQ I'll end up with?
All you need to do is to duplicate the equalization curve of the origional
type II equalizer. Hopefully, you can find it documented some place.
The best way to obtain a given equalization curve is a parametric equalizer
with 4-6 bands per channel.
If you have documentation about what the desired equalization curve is, your
remaining problem is to set the controls of the equalizer appropriately. A
relatively rapid means would be needed for accurately measuring the response
of the equalizer. I can think of several ways to do this, but the most
economical means I can think of would be to use the audio interface of a PC,
looping the line output of the PC through the equalizer and back into the
line input of the PC. Software that measures frequency response quickly,
such as the freeware Audio Rightmark software would let you know when you
had the equalizer's controls set appropriately.
http://www.rightmark.org/