In this article I want to show you some snippets of my building process of the Serge Wave Multipliers (VCM).
About the module
This module consists of three sections. The top one is the simplest of these. It can be used as an ordinary linear gain controlled VCA by setting the switch to the low mode. The high mode squares up the incoming signal. The effect you get from it is similar to an overdriven tube amplifier, but voltage controllable.
The second wave multiplier comes with two inputs to mix two signals. By turning the potmeter up you get odd harmonics so you can make a boring sine wave more interesting. The amount is voltage controlable. You will get awesome sounds from it!
The wave multiplier at the bottom produces even harmonics and has also two inputs. It kind of sounds like a distortion. It also has two outputs where one of them is the squared up version of the other. It can produce pretty harsh sounds.
The building process
As always, my stripboard layout is pretty densly populated. This is because I like to build my modules compact to make the most of the available space I got. I also try my best to fit all the components on one board. I used the following layout for my own build. You can download the high resolution layout and schematics here:
The schematic of the third multiplier calls for three 1µF bipolar capacitors. These don’t count as a standard part in the stock of general electronics retailers though. However, there is a workaraound to that problem. Kindly, Eddy Bergman sent me an easy schematic on how to build bipolar caps with higher capacitance on your own. You can of cause also use polyester caps. This is how it works:
I just soldered the caps and diodes point to point and this it how it looks like:
Calbration
The calibrtion of the top and middle wave multiplier is pretty straight forward. Just put an audio signal into the CV input and turn the CV potmeter all the way up. You will hear the signal coming through. Now turn the trimpot until you can’t hear the signal anymore. I used multiturn trimpots since that’s what I got in stock. You can also use single turn ones. There is even a video showing how to do it:
Here are some pictures of my build:
When looking around in the internet, I noticed that there aren’t really any easy demos of it availlable. To get you an idea on how it sounds I recorded my own. As you can see, the third multiplier is folding the sine wave although the potmeter for the folding amount is turned all the way down. I don’t know if this is normal, but for me it’s no problem.
That’s it. If you like what you see or if you got any questions or feedback just leave a comment or come over to my Facebook group. Thanks for tuning in!
Moebius Synths 