I've been taking a break from analogue circuits to investigate the world of DSP using an ESP32 microcontroller and the Faust DSP librares. This has been quite an adventure involving building my first dedicated Linux computer with PlatformIO running in Microsoft VS Code. So far I've got it running three sawtooth oscillators, a noise source, triangle LFO, amplitude and pitch envelopes and a simulated Moog resonant filter. The I2S interface produces impressive 24-bit sound quality at 48kHz sampling rate. Unfortunately the Faust delays and reverbs seem to make the processor brown out and it goes into a reboot cycle. More work required. Or possibly just a lot more memory. That couldn't hurt. The crackling noises are due to having the record level turned up too far rather than any problem with the synth.
Well, we're all confined to our homes while the COVID menace stalks the streets so here's a good old blast of insanely resonating modular synth with some 808 drums from Native Instruments Battery.
Just got this one completed and working. Uses the classic (reissued) CEM3340 chip as used in so many classic synths like the Sequential Prophet 5, Roland SH-101 and many others. The PCB wasn't quite right so I had to bodge wire a resistor and capacitor into the CV mixing section, not really worth fabricating a new PCB though as the finished module works very well.
What to do, what to do. I just can't decide.
I know. I'll make strage noises on the modular.
After several failed PCBs, we now have a working version that reads frequency from the modular! So far I've burned out four Arduino Nanos and a 20x4 LCD display module but we're getting closer to a working unit all the time. Next step is writing the rest of the firmware for the Nano to control the DAC and the 4066 switch.
I stumbled across a video demo of a clone of the Buchla LPG on Youtube and was phenomenally impressed. So much so that I knew I had to build one. It's an ancient type of filter using Vactrols, a combination of an LED and a light-dependent resistor to effect a frequency response change. And it sounds wonderful.
The first PCBs aren't quite right, I managed to omit the two voltage tracks to the ICs so this first version is patched up with a couple of bodge wires to make it work. Only smoked one opamp making it, a new record.
Currently on the production line is another kit from Rick Holt at Frequency Central. This one is the fabulous Meth Amp, effectively a clone of the EHX Big Muff in Eurorack format for those insanely distorted TB-303 squelches. Should be ready within a week if the Alpha pots arrive soon.
Having made a complete fuckup of two previous boards by putting the voltage regulators in the wrong way round, I've rattled through building this new version. One more board to build then the modular cases will finally be ready for me to transfer the synth modules into.
I never quite understood the term "Berlin school" synthesis. And President Kennedy's famous declaration translates as "I am a doughnut". So maybe this is doughnut school improvisation. Anyway, it's the modular synth doing its thing while I remain only nominally in control of the sounds it produces.
I have been known to occasionally provide guitar for my brother's outlandish space rock project, Brotherhood of the Machine. Strangely, I go far more crazy apeshit on other people's recordings than on my own.