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...

The 247v Sequential Voltage Source

I have been working on a new Sequential Voltage Source. It is only a single module space and packs a big punch. It does most of the things a MARF or ARF does, but without any menus. It can act as an 8 stage sequencer with two rows, voltage control of the clock/slide rate, switchable slides/pulses, pulse outs on each channel and the ability to loop from any stage to any stage.  It can act as a multi-stage envelope, up to all 8 stages with any stage as a sustain stage or any stage pausing unless a key is held. It can act as ADSR, AHDSR, HADSR, AD, AR, AHD, LFO saw, pulse, square, triangle, something more complex, LFO that only runs when a key is held, LFO that only runs when a key is lifted.

I wanted a small sequencer with every function on the panel. I wanted to do TB-303/MC-202 type sequences with slides selectable per stage, where the pulse output holds the whole stage on a slide stage but only pulses 25% of the stepped stages. I desperately scrambled to complete two for my performance during the NAMM show. I made panels from PCBs because they take less time to manufacture. I only got one finished and then it didn't work when I got there! Anyway, it's working now. It's pretty fun.

getting my modules together

After a month of downtime, I am back in the saddle. I got tonsillitis and had to go to the hospital, then my grandmother died. It's been a bummer, but I've done a little bit of work on a couple modules that I'm ready to show. These pictures are just the panel designs on paper with knobs laying on top, but they give a suggestion of what the finished modules will look like.



The first is a clone of an oldie. I don't care too much for the idea of cloning old modules (I'd rather do something new), but people keep asking me about 258 oscillators. It makes sense that some 200e users would crave the raw analog sound of the classic 200 sound source. There are a couple things that make this a funny one to re-do in modern times.

The first is that it used a µA726 matched transistor pair. That transistor is heated to maintain a constant operating temperature, so the scale doesn't drift as it heats up. This part is long obsolete. Although I could buy NOS ones on ebay, I have decided that this is not the best idea. Since the 259 uses a regular matched pair and a tempco resistor and the 208 switched from a µA726 to a regular matched pair and tempco in one of it's design revisions, I figured it would be ok to do this one with an LM394 and a tempco resistor. I also have redone the PCB so that all the panel controls mount on it. It makes the module much cleaner looking and less prone to failures. If the pots fail 20 years from now and nobody is making the same ones I have used, one could always panel mount some and wire to the PCB like the original design. It could be built up using the original knobs, blue knobs (if I can get the big blue ones!) or the ones Don is using now on the 200e modules.

The second thing is that the 258 has no keyboard input. Don decided to put a fine tune on the left-most CV in instead. I have never cared much for this and have entertained several other options. The first idea was to put a push/pull pot in the left-most position and when it is pulled engage a trimmed CV in rather than the scalable one that is normally there. Grant Richter told me he had done this on an actual Buchla 258. The problem I have with that is the depth of those pots would require really long stand-offs and panel mounted pots. The second idea I had was to put a gray banana jack in the hole where Don put the fine tune control on the left. This would work, but I don't know that I like having a banana jack in the area where the knobs are, call me weird. The final idea I had was to put a toggle switch where the fine tune was. If it's up, the input is trimmed 1.2volts/octave or whatever and if it's down, the CV goes through the control. I have set up my PCB so that the original fine tune control, the banana jack or the switch are all possible. I plan to try them all out and decide which suits best.

Although I did a couple 258 clones a few years back using a CA3080 instead of the discrete transistors in the core, I found the triangle symmetry to be imperfect and the whole exponential converter had to be changed to use a PNP pair, hence this module will be true to the original design using discrete transistors.


The second module I have ready to order parts for is the Quad Voltage Processor I wrote about last month. I thought I could get all the parts between the controls on a single PCB, using SMT, but I found that it was more parts than I anticipated. It is a motherboard with all the panel controls and a second board with the actual circuit. Since this is essentially 2 whole 257 modules, each with an extra CV input, I think that is respectable enough. I'm really looking forward to getting this one built up. This will be a boon to small 200 systems, where it will solve many control voltage situations.

Anybody interested?