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Buchla CV standards -- Vintage Buchla 2.4v/octave?
MUFF WIGGLER Forum Index -> Buchla, EMS & Serge  
Author Buchla CV standards -- Vintage Buchla 2.4v/octave?
sanders
It seems to be pretty widely reported and generally agreed that the 200e uses a 1.2v/octave or 1.0v/semitone CV standard for VCO tracking.

However, the same is not true for vintage Buchla VCOs. I've been wondering about this for a while now and only just recently found two reliable sources ( Daniel Scheidt's 1981 Buchla User Guide and Dale Millen's Univ Arkansas Buchla System Abstract) that report the 259 VCO having a 2.4v/octave or 1.0v/quarter-tone scale.

I'm just wondering if there's anyone here who owns a 259 and has found this to be the case in practice for one, and also if any of those same 259 users have found some means of controlling their 259s at 2.4v via MIDI or otherwise.

I'm interested in a way to incorporate a 259 into a volt per octave world and looking for advice.
dougcl
Perhaps off topic, maybe not. You can use the 251e to quantize up to 100 incoming CV voltages to arbitrary outbound CV (even nonlinear).

midi->midi2cv(1V/oct)->251e->259(2.4V/oct +/- nonlinear error).
divisionbyzero
2.4v/oct is curious because it only allows for a 5 octave range (going by the paper which states the cv range for pitch is 12.7 volts), not nearly the full actual range of the 259. My 259 was calibrated to 2v/oct when I got it which gave it around 7 octaves of tracking when playing it from a 112.

I was going to add scaling options to the 225e so I'll make sure to add 2.4v/oct as one of the options (1v/oct, 1.2v/oct, and 2v/oct being the other choices).

.6v/oct would be interesting too to allow for quarter tone play on the e-series oscillators.
blindoldfreak
yup. my 259s are 2v/Oct too, and the 221 spits out the same.
danox574
I've also seen the 2.4V/octave standard referenced in the guide for the Buchla 300 as the type out output you'd get from the 219 keyboard. Music easel schematics appear to use a 0-13.5V range for control of several things, including a 55Hz-1760Hz range on the complex osc (although the slider does a little more range that that), so it seems to be about 2.4V/oct. The complex oscillator easel schematic does have 1.0V/octave written near a scaling trim pot as well, though, and it appears that the ranges were altered at some point during the schematics life.
sanders
sanders wrote:
It seems to be pretty widely reported and generally agreed that the 200e uses a 1.2v/octave or 1.0v/semitone CV standard for VCO tracking..


This is a typo, I meant 0.1v/semitone for 200e and 0.1v/quartertone for 200 series. But, if the 259 is indeed 2.0v/octave, then I guess it's something close to 0.166/semitone (I think).

I have built most of my 200 system, and I'm getting increasingly interested in figuring out some sort quatization device for incoming sequence voltages.
Zentek
sanders wrote:

I have built most of my 200 system, and I'm getting increasingly interested in figuring out some sort quantization device for incoming sequence voltages.

If you can host Eurorack modules in your setup, the Klavis CalTrans can play your Buchla (whatever V/Oct version) VCOs quantized, from Eurorack pitch control at 1V/Oct.
Peake
I've cloned the original 144 and 158. From my build blog:

Scaling: A friend recorded an original 144's pitch response to several voltages.

At 2 volts, it produces G0, 24hz.
At 4 volts, it produces E3, 164hz.
At 6 volts, it produces a very flat D4.
At 8 volts, it produces a very slightly sharp Db6.

It appears to wish to be E3 through E6, from 4V to 8V, which is 4V = 3 octaves.

(No idea why a 259 would be 2.4V/Octave although some of the 258s were closer to 1.8 to 2.0V/Octave, IIRC.)
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