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…

uLFO

Got a couple of new modules this week. The MFB Dual ADSR will replace the Doepfer A140. It’s got two ADSR envelopes, each with a “hold” state as well as the expected attack, decay, sustain and release. The envelopes can be triggered individually or together, and they each have two outputs. This is all great.
The Bubblesound uLFO is at its heart, as its name suggests, a low frequency oscillator. But it’s more than just that. It can go really really slow — something like 20 minutes per cycle — and it can be tracked at 1v per octave at audio rate, which basically makes it a secondary VCO. I’ve been wanting to learn more about FM synthesis and this is my first module that has a linear FM input. Both of my VCOs, Doepfer A110’s, only have exponential FM (at some soon point I plan to replace the 110s with a Cwejman VCO6 and a Harvestman Hertz Donut but they’re hard to come by right now).

uLFO and MFB dual ADSR

One funny thing about the uLFO. On Monday I noticed that the response of the SIne Shaped output seemed odd. This is a unique feature of the uLFO. It’s got a regular sine output but it’s also got a “shaped” sine, which basically creates what the Bubblesound website calls positive/negative biased non-linear triangles. The wave forms look like waves as drawn by a kid on one side, and bumps or the McDonalds logo on the other. However, I noticed that the shapes it created were the opposite from the icons indicated on the panel of the uLFO. I made a little movie to send to send to Bubblesound to make sure that I was hearing it right.

I posted this to the Muffwiggler forum, which got mixed replies. To make sure I wasn’t going nutty I ran the waves through my CueMix oscilloscope which proved that yes, I was hearing it correctly. Later, David at Bubblesound wrote and confirmed my observation. Regardless of this little quirk, this is a terrific module and I look forward to posting more here from the uLFO.