Video of the new Verbos 247v sequential voltage source

Here's a quick video of my 247v module in my Buchla 200 cabinet. It shows some of the sequencing features. The 247v is connected to a 259, 281 and 292. The 281 is in sustained mode to get the benefits of the variable pulse length on the 247v. To start, I run it from it's internal clock and switch around the stages' on-off-slide switches. Then, I run it from an external pulse from the 281. This shows how the TIME MULT control acts like a pulse length/slide length control. I then show some tricks with patching stages into the strobe input and send in voltage to the analog input from an off stage 254 to select which stages are playing. There are loads more features, using the yellow inputs to make envelopes and stuff. I hope this starts to show it off...

Quantizer/Analog Shift Register take II

In 1972 as a resident at CalArts, Fukushi Kawakami made four modules as additions to the school's rather extensive Buchla 200 system. The modules are a Control Voltage Switching Matrix, two Control Voltage Integrators and what I believe is the world's first Analog Shift Register. 

http://barryschrader.com/the_fortune_modules/

Since then, the world has fallen into disarray, computers have taken over, analog modulars have gone in and out of favor several times and those four Fortune Modules have ended up in Grant Richter's hands. Somewhere in the middle of all that, Serge made an analog shift register and wrote about it (under the nom de plume Arpad Benares) in Synapse. Even before the Fortune Modules, Buchla had made a rather amazing Control Voltage Integrator called the 155, but that's another post.

Anyway....

Analog Shift Registers are a bank of Sample and Holds. In fact, using only the first output, it is a Sample and Hold. When a pulse is applied, the CV on the input is stored on output one. Whatever was on output one is moved to output two, and so on. 

In 1997 I made 2 copies of a module that was a dual four stage analog shift register as well as an 8 channel voltage quantizer. One of these is still in daily use over at OSI music and the other is rotting on a shelf in my shop. When this photo went around the forums and blogs some people suggested that rearranging the panel to allow the analog shift register outputs to be quantized via shorting bars would be a good idea. Point taken.

 

I had a couple of ideas of my own that could make it a better module. Sadly, it got back-burnered and never saw the light of day until now. The new version has rotary switches to select the scale to quantize to. The ASR outputs can be plugged into the quantizer with  shorting bar. There is no longer a "slave" switch to chain the two ASR's together, but a cable and shorting bar can now do that too. Some new ideas have come up as well, like using the quantizer to look-up the voltages from the "random" voltage sequences from the 266. It's obviously not as glamorous as an oscillator or filter, but it will come in useful to some people.

MARF making

I repaired a MArF a few years back, but nothing was like the undertaking of getting the 248-3206 from the Buchla garage sale working. I only know of a couple of these in existence and I don't know that any of them work. Someone bought the panels with only the motherboards attached. I have had them in my possession for more than 2 years. I had to design, assemble and troubleshoot the input board and 3 output boards for this beast. Each board is 14" x 6" or so, no small task. Today it worked for the first time.

Pictured is the working MArF as a reference. and the 2 panels from the double size expanded unit. A 3206 is a normal 1602 unit with an additional 4 space panel added to it. The expander adds another 16 stages of sliders and memory as well as 4 more output channels. The 6 total output channels can address the 32 steps in any way. This thing could be a 200 system's only source of modulation generators. LFOs, Envelopes, Sequencers, Quantizers, Voltage Processors are all possible. More infos to come.

Much more info to follow.

1.2 volt per octave input

Pictured is the 258v with the addition of a trimmed 1.2 volt/octave CV input (the grey banana jack on the left). I have decided to go with this system because it gives the trimmed CV in I want, but doesn't take away any other inputs or outputs. The fine tune control for the left most CV in, I believe only was useful when scaling that input for a keyboard.

I'm working on them, and still waiting on the Selco knobs...

funny waveshapes

Some people think that a good waveshape is one that looks like what is printed in a textbook. A clean SAW wave is not always the best sounding one. Buchla 259s do not address the waves at the main output by the way they look, but rather by their harmonic content. Sure, there's a square and sine output, but the main output is a blend between even and odd harmonics, between hi and low order harmonics and between lo and high timbre. This always seemed, to me, like the better way for a musician to deal with oscillator output. The 258 claims to have a saw and square wave, but I feel that the spirit has always been about even or odd harmonics. They crossfade from sine to saw on the top oscillator and square on the bottom. The waves never look perfect, but they sound so good that the oscillator has a cult following. People clone it left and right. The above 'scope pics are from the prototype of my clone.

Here you will find some scope shots from an actual vintage Buchla 258C:

http://www.synthtech.com/pix/buchla/b258/b258_w1.jpg
http://www.synthtech.com/pix/buchla/b258/b258_w3.jpg
http://www.synthtech.com/pix/buchla/b258/b258_w4.jpg

Looking good. Sounding good. Feeling good.

Ruff Club

This is just a rough mock up of what I have been thinking about for a single space mixer. It's 6 channels, each with voltage controlled and manual level and panning. There is a stereo, unity gain expansion input and a mono output. A mute switch on each channel. The 3 channels to the left pan right with higher voltage and the 3 channels to the right do the reverse. Panning is equal powered, so there is no dead zone in the middle. I think it fits the bill.

Music Easel Oscillator

The oscillator section in the 208 module can be seen as a rest stop on the way between the 258 and the 259. The "timbre" section is introduced as well as a switch to select waveforms. It's the first time Don implemented a dedicated modulation oscillator and trimmed keyboard CV inputs.

Interestingly, the original version of the 208 used a totally different design than the 258 or the 259, with Vactrols in the oscillator core. I don't know how many of these were made, but it was fazed out in favor of the 259-like design you can find schematics for on the web.

The "Timbre" control introduces wave folding on the sine wave, but does not effect the other waveforms at all. There is a separate, unlabeled knob above the waveshape switch that controls the mix between sine and the other shapes. The wave folder's effect disappears at the full CW position of this control.

I built a clone of this oscillator about 6 years ago, using 2 single sided photo etched boards. I modded a few things to make more sense in a dedicated module. There are a few lessons I learned, that I would do differently, if i did it again. It is a nice design and I think it has validity, even alongside other Buchla oscillators.



Going through my box of abandoned old PCBs, I got the idea that maybe this would be a cool module to throw together, considering the hype surrounding the Music Easel. Maybe it's time to revisit this one....

Musings on Voltage Processors

Some time in 2007, the idea of "building a better voltage processor" came up between Reed and me. The problem goes like this....



256
pros: good for mixing, inverting and scaling. Huge output voltage swing possible, for black knob era systems where you really need 15 volts to open some parameters.
cons: All it can do is mix and invert. Only 2 sections. No indicators. All black banana jacks. (just kidding Rick)


257
pros: able to mix, scale, invert, crossfade, manually offset, VCA
cons: no gain, can only mix 2 CVs. Because it uses PWM for the crossfade, it doesn't like audio rate CVs. Only 2 sections. Confusing nomenclature.

256e
pros: able to crossfade. invert, scale, mix (kinda). Breakpoints!
cons: only will work with up to 10 volt CVs. No real mixing.



The first idea was to make a quad voltage processor module that had 2 sections of 256 clone and 2 sections of 257 clone. That seems like a cool enough idea, but then I thought, "what about making a design that can do what both do and including 4 of those?"

The idea is to have the ability to mix 3 CVs, crossfade, scale (from a knob or another CV), offset. It should have an LED to show it's state. I had a design made up and a front panel worked out, then my laptop was stolen by a Gypsy in Barcelona. These print outs are all that remain. Anyway, I am ready to dive back in and I will get something together.



It will be like a 257, but with 2 reversable CV inputs. The PWM crossfader will be made from newer, faster parts. So the cutoff frequency will not be so low. The 257's triangle oscillator, for the PWM, is 21kHz. I think I'll try to take it up to 100kHz or so. This shouldn't be a problem for modern analog switch chips. I think I'll use center detented pots for the reversing CV inputs. Here's the 257 schematic, BTW.



With this configuration, you can mix 3 signals, one with voltage controlled gain. It's not the 4 signals of a 256, but it's close. It can do everything a 257 can do, with a bit more speed. It's 4 processors in one module space. It'll have LEDs on the outputs. the output will not swing a full 15 volts, because I don't want a 24 volt supply line (200e and many 200 systems don't have one). It won't even try to do the breakpoints, we'll leave that to the 256e.

The 266 project

The Audities Foundation got whatever parts were left in Don's archives during the garage sale about 6 years ago. Included in that lot were 2 unused 266 Source Of Uncertainty panels. I built this one and am working on the other.

Obviously, this is a very popular module and every Buchla user wants to have one, but without any circuit boards nobody was jumping at it. A couple "kits" for this module went out the door at the same time. So I was fortunate to track down some scans of the circuit boards without any parts installed. Then came the long process of cloning them. This module has 3 PCBs inside. The motherboard (with all the panel components on it), A and B.



I know, I know. "They're not blue!" Well, I didn't feel that it was necessary to make the PCBs the same color as the originals. The second cry is, "But there are no orange banana jacks on MY 266!" True, the original release of the 266 used red banana jacks for both pulse input and pulse output jacks, but since Don changed to orange for pulse inputs in the late 70s and is still using that standard today I went with the new standard. It turned out that I made several errors in my cloning of the PCBs, leaving short traces between pins on ICs off. It's ended up working after a little stress and now lives happily between a 265 and a 266e. Long live the Source of Uncertainty.