Buchla 256e Control Voltage Processor: Applications, Use, and Tricks

The Mighty, and Mightily Misunderstood, 256e Control Voltage Processor

This is a unique control voltage processor, regardless of the format. It is also unique in the Buchla brand in that it provides the only way to have VCA-like control over CVs, LFOs, and such. The Studio.h 254e does provide this kind of pseudo-VCA feature though and is an option for the “all analog man or mistress”.

The Breakpoints are wholly unique, are incredibly powerful; and I find them to be indispensable. As you’ll see and hear, they allow an incredibly detailed and personalized amount of fine-tuning of CV response. This is invaluable when used with a touchplate controller of any sort.

00:00 Start o’ fun!
00:24 4 Functions
01:00 Transfer Function explanation. How disting work?
02:24 Biasing
02:35 Attenuation
03:00 Constrain Voltages within a window
03:25 Constrain & Invert
03:49 VCA/Crossfader
04:43 Crossfade + Attenuate
05:17 Remote Crossfading
05:51 Breakpoint & Frequency Doubling
07:20 Frequency Doubling w/atten AND/OR waveshaping
08:30 Inversion
09:00 Attenuation
09:34 Biasing
09:43 VCA for CVs
11:12 Studio.h 254e will do this as well
11:19 Breakpoints with 223e Touchplate
14:28 Fine-Tuning Pressure sensitivity
15:13 Making a button. Dividing Touchplate key via breakpoint
16:10 Breakpoints w/Attenuation
16:20 Crossfading Audio via Inversion
17:52 Auto-Panning Ticks
20:00 Auto-Panning Frequency Doubled via Breakpoints
21:08 What would you like next?


A few notes:

1. The video is a bit less well organized than what I like. I contracted COVID-19 a few days before shooting the video and it still has its dirty hold upon me. One of the weird and annoying side-effects is that it really messes with a person’s short-term memory and ability to organize one’s thoughts. I ended up having to insert a bunch of explanatory notations into the video. At least it keeps the video shorter when you forget to mention things!
2. This video is not a complete display of applications. Most of the applications can be combined. Channels can be cascaded and so forth. The only fixed limitations are channel count and destinations.
3. I could get by with the 256e for CV stunt work and the Studio.h CSR (improvement upon the 210e). These are the two processors that I recommend first with the Studio.h 254e coming in third. I do own one of each.
4. The Studio.h 254e will cleanly pass and mix pulses. It is also accurate enough for pitch CVs. Jon Schatz (former B&A employee and creator of the ID700 iOS app) did manage to optimize the code within the 256e during his late days at B&A. This greatly improved the module by increasing the resolution by 10 times. It still isn’t perfect. It’s still sloppy about passing pulses. It is currently as good as it will ever get as we’re capped by hardware limitations. It is, nonetheless, an outstanding module.
Firmware as of this video is v30.3

5. Hopefully, I can remove this one after it is fully processed. YouTube compression algorithms seem to have made the narration sound distorted. This certainly isn’t my doing and I was diligent about this when reviewing the video.



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Lemme know whatcha want!