testing 142

I’m constantly figuring little things out about this synthesizer and I feel, in many ways, that in the five months I’ve had this modular thing I’ve learned more about synthesizers and sound than in the years and years previous working with software.

I recently added a Doepfer A142 to my system. This is a voltage controlled decay/gate. What it does is takes a trigger input, like from a LFO or in my case the MFB Seq02, and creates an envelope that consists of a very quick attack and a voltage-controlled and adjustable decay. What I was looking for was a way to create steps of different lengths from the sequencer to add some movement and, you know, funk. I could do this with my Model 10, but I like using the Model 10 so much that I figured I’d like to have something that is dedicated to sitting next to and serving the sequencer.

Soon after plugging it in, I started noticing that something wasn’t right with the A142. It didn’t have a “quick” decay, only a really muddy longish one. This was especially the case with manual control. When I plugged the CV in, I could get sharp clicky envelopes, but in manual they were anything but short even with the knob at 0. I discovered that on the PCB of the module there was a small trim pot, but I didn’t know what it did as the Doepfer site didn’t seem to refer to it.

So, as I do at times like this, I turned to the internets and started a thread at the Muffwiggler forum. I immediately got some help and much of it was quite thorough and technical. Just having others tell me that their A142’s work as expected at least narrowed it down to a problem with my particular module. One or two readers actually got deep into it and with this information I at least got the thing usable. The trimmer on the back adjusts the offset, which means that it adjusts the point at which the envelope starts getting longer. By turning it about a quarter-turn, it’s now set to where from 0 to 1, the envelope is about 1ms long. This is a good thing. A new problem begins at 1, because by 3 the envelope is more than 12 seconds. This in theory should take place at nearly a complete turn, like around 9 or 10. So the entire range of the envelope is now between 1 and 3, which means that very very small nudges to the knob result in very large changes to the length of steps from the sequencer. From incredibly staccato to very very legato.

To illustrate this, I made a video. It includes captions for clarity, but basically I set up a simple sequence in the Seq02 and make adjustments with the A142. You can see the minor little changes to the knob and hear the major adjustments to the step lengths. The advice from the forum was to solder a new resistor onto the PCB. I’ve been meaning to learn to solder…