[sdiy] Re: [AH] Buchla VCOs

[Peter Grenader]

Let's not forget that even if the oscillators were set up for 1v/oct
tracking (which after the point I'm about to make they would be pretty much
useless), there was no keyboard controller available to generate equal
temperament until the late 70's which was way down the line in the 200's
development.

In short, Bob Moog's and Don Buchla's vision used similar means to come to
very different conclusions. Neither is better or worse than the other, just
different.  

This being said, the Buchla oscillator's VC inputs were such that these
later day equal temper'd touchplates could be tuned for that.  No, there was
no scaled inputs, but it is quite easy to adjust the attenuators so that one
could arrive at that if one wished.

P



 Paul Schreiber wrote:

> 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
> 
>