Buchla CV question

[Grant Richter]

> I don't know much about Buchla modulars, so I may be
> very wrong here. Apparently he used separate CV and
> audio connections (different jacks).

The Buchla 200 system uses three voltage systems.

Audio signals use 1 volt p-p and 1/8" connectors.

Control voltages are 0-15 volts on Black, Blue or Purple
banana jacks.

Timing signals are 10 volts for gate with a superimposed
+15 volt pulse for trigger (on the same line) on Red banana
jacks. All timing signals are diode isolated for wire OR.

The power supplies in a Buchla 200 are +24,+15,+12 (Vactrol led supply),+5,
Quiet Ground, Noisy Ground, -15, -24 on an eight wire harness.

> I noticed diodes in some CV output circuits I've seen.
> Could it be that the philosophy was to have
> a kind of "analogue wired-or" function, where the
> current *maximum* of all CVs would be used, rather
> than ordinary mixing / addition ?
> Or was it ordinary mixing when searate input jacks
> were used, but maximum function when both sources
> were plugged into the same input jack ?

That is true of the Buchla 266 SOU, but it is the only place
I have seen it. Yes you can wire OR the outputs and the
highest voltage will prevail.

> Related question: Were the Buchla CVs generally 
> unipolar (positive only), or were there bipolars
> CVs as well ?

All the CVs were unipolar because each input has
a +/- attenuator. Because the only transconductor
in a Buchla is a Vactrol (no OTAs at all in most modules)
the audio path and CV path are optically isolated
from each other and use separate power supply lines and grounds.
The CV circuits use 741 op-amps and the audio portions use NE5532s and
5534s.