Drum synthesizer - Finished

The case is ready, and all functions are working! :) There are small problems, but I will fix them soon.

It's really fun to play with it, especially the cross-modulation functions, and the triggering combined. It can produce sounds from funny, and simple synthetic "space" drum sounds, to agressive, and noisy, industrial drums, even cool analog bass sounds, and simple synth sequences! So much possibilities are in this "simple" instrument. :)


A little summary of the instrument:

Analog drum machine, and filterbox.

Features:

• Two independent drum channels, based on Coron DS8 design.
• Two Wasp VCF clones, with LP/HP/BP/Notch modes
• External signal processing with the filters
• Triggering with button, or external signal (audio, piezo pulse, etc.), led indicator
• Inputs for VCO frequency CV
• VCO frequency modulation (or cross-modulation), with VCF output of the other channel
• VCF CV input
• Separate outputs, or mixed out

Sound samples will follow soon!

Drum synthesizer - construction 3

The front panel is ready, and the drum synth has a new PSU too. The electronics is completed, now I need to design a case.

Drum synthesizer - contruction 2

I've finished the rewiring of the panels, and the drum synth is now working with it's own external 9V DC PSU. Two separate piezo triggers can be used to fire the channels independently, it's a lot of fun. :) Sadly, the DS8's output signals are too quiet, or not ideal for the Wasp VCF, even if resistor R30 (100K) is replaced by a 470K one.

I also need to process external signals, so a preamp will be included:

Preamp, and mixer circuit on veroboard:

Drum synthesizer - construction 1

I'm in the middle of the building phase. The two drum voices (with the Wasp filters) are working properly! :)

I've made a temporary, cardboard faceplate, because I need to finalize the graphics. I need to make an extra PCB with the VCF LFOs (4069 LFO), some preamp for external input signals, a 555 negative supply circuit, and maybe a headphone preamp too. I also need to make some experiments with cross-VCO modulation between the two DS8s. If it sounds good, I will put 2 pots on the front panel with this functionality. I will make experiments with Wasp out -> DS8 VCA in feedback loop. I like distortion... :)

The "Rebel.D2" drum synthesizer

I like to run projects in parallel, so there is my new idea: I want a simple, analog drum synthesizer.

I've built a Coron DS8 clone from Marc Bareille's schematics. I don't have CA3080 OTAs, so I've redrawn the circuit to use LM13700, and integrated a led driver for the incoming trigger signals.

After a few hours of playing with the DS8, I've realized, that this circuit can be enhanced with a VCF. The DS8 doesn't contains a filter, only the noise spectrum can be altered with a switch.

Because the DS8 is using +5V supply voltage, and the Wasp VCF also using this value, I've tried it, and built this combination, plus a piezo trigger pad into a temporary plastic case for trial.

This combination sounds wonderful, warm, and analog, but it also can be harsh, distorted and rude. This VCF simply mutiplies the possibilities of the DS8.

Then the idea of a simple two channel drum synthesizer was born:

I don't want to integrate any control circuit into this machine, only the CV/control/trigger jack sockets will be built in. The Wasp filters can be used for external signal processing, so this unit will be an integrated drum synth and a dual filterbox.