A great monophonic analogue synth like the Dark Energy sounds great, no doubt. But it still has only one VCO. So there is for example a suggestion how to fatten up the sound of the Dark Energy with the help of some Doepfer modules: http://www.amazona.de/index.php?page=26&file=2&article_id=3322
By adding two more VCOs the sound get's fatter and richer. There are a lot of sound examples on the site that excited me and got me thinking how I could get that cheaper. Because building the proposed Doepfer minicase would be something around 430 €. That's a lot!
So I decided to make it with two monotrons. I modded both to be able to control them via cv pitch and gate and connected both to the cv1 and gate output of the Dark Energy.
After mathching the pitch range with the trim potentiometeron the back of both monotribes I did some testing and it's a nice combination. I made a little jam later on. It's hard to get the monotrons in correct tune with the Dark Energy and with each other, because the pitch potentiometer of the monotribe is very sensitive. But the thing about fatter sound through more VCOs is that it sounds fat because the VCOs are not exactly in the same pitch. Adding filter or pitch modulation to the monotrons opens a wide range of possible sounds together with the Dark Energy that also has Frequency Modulation and other cool stuff.
More pictures of both monotrons added to some kind of hounsing with a 5V Power Supply and jacks for pitch, gate and cutoff.