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... :)