Archive of the former Yahoo!Groups mailing list: MOTM

OK, I'm not a Buchla expert, but I can see an immediate reason it was hard to do "Carlos music"
on them.

The VCOs have NO straight 1V/Oct inputs! On the dual 258s, there are 2 exponential FM ins (both
on reversing attentuators, with a coarse AND a fine adjustment) and on the linear FM. just a
straight attenuator.

I suppose the thinking was to use the combination of Coarse/Fine attenuators to get to 1V/Oct,
but this is a doomed operation.

The actual circuitry is a straight-forward 726 heater expo converter, a hand selected
hi-frequency track resistor (about 3M) with LM741 CV mixers (ugh).

It's obvious from looking at 1/2 of the modules that Buchla loved the military surplus stores :)
The boards are a hodge-podge of decent 1% RN resistors mixed with carbon comp. The VCO trimmers
are not precision, but cheesy ones. Every board uses different transistors. Trimmers are use in
some modules (the frequency shifter has like 8 of them), but I guess I'm not into the 'West Coast
Sound'. I think a 1V/Oct input with a 10-turn trim would be nice.....and knowing Don, he probably
did this ∗on purpose∗ to cause 'interaction' to 'find your own center of VCO happiness'. Whatever
:)

I would have use a switched pot, so that you had a choice of fixed or variable tracking. Guess
they were out that day when he went shopping :)

Paul S.
break time