You really should look at the datrsof the posts. But I will respond for the hell of it. I got one.

I looked at it and there is not much about the output stage, FM or whatever, but there is a bunch of stages of OP AMPs in there that must have no other purpose but to do some really fine EQ. I mean stage after sdtage, combined OP AMPs in different stages.

This is all obviously to as accurately as possibly counteract frequncy response variables and phase shift in their particular speaker system. that's why you can't really dupolicate their EQ for the 901s with a regular ten band. You might get close, it will sound good, but not that good.

Eliminating the phase shift is important in keeping those peaks and valleys out of the frequency response curve, and though they do not do a perfect job, they at least make it sound pleasing.

IIRC, there are alot of unmarked components on that print. Some are marked, in fact I belive that in the EQ section they are marked. But look at the configuration of the amps, it is a rat's nest. This EQ system was obviously designed by instrumentation engineers. Someone capable. It is so ****ing precise it is ridiculous. Of course we canot prove that becaue what, get a calibrated mic out there ? It is meant to match THEIR speakers.

The old Boses had a woofer on one side with a smaller but matched in higher freqs on the left. It used a longish cavity through the back of the cabinet to make a bass reflex system. Later models used two woofers and had the vent or whatever out the back. Sounds ghood but I have no idea which is better. I actaully have heard both, but they were years apart and in totally different environbments so ther eis no way to compare.

Watch the dates here. Nobody should say never respond to an old post, becaue if YOU had one to fix or whatever, what the hell ? Sometimes you do find a print from an old ass source at a university or something.

But trying to help anyone gone for a long time just, technically, spams the group. Unintentionally of course but the end result is the same.

But it gave me some rant time :-)

You should look it up, see the print for that MF. That EQ circuitis out of this world.