I’ve finally finished the current batch of modules! But I do have a bit of a problem - the new cabinet which I haven’t even started building is already over 3/4 full…
Here’s a list of the new modules. Click on the name if you want to see more details, otherwise this would be an impossibly long post!
MFOS ADSR
I already have a YuSynth ADSR which suffered from the ‘not returning to 0V’ problem. That’s fixed with a diode in the output stages, but I thought I’d try a different circuit for this second ADSR - hence the MFOS design.
Voltage Influenced LFO
Based on the Pittsburgh Modular VILFO design. I didn’t like the lack of buffering on the outputs, so I added buffers and also a pulse wave output. The circuit generates a pulse wave, so why not have access to it!
Sculpt-O-Sound Trigger-To-Gate-Convert-O-Matic
Found right here! Built with ferrite beads on the power inputs and without the crowbar diodes.
YuSynth multimode Steiner-Parker VCF
I like this VCF and built it quite a while ago, but it got pushed out of the cabinet to make space for an MFOS VCF with voltage controlled resonance. It’ll be nice to have it back.
Quad Quantizer
Originally inspired by Hagiwo’s dual quantizer, this has 4 5-octave output channels using a MAX5175BAUD quad DAC and flexible trigger generation options. It uses an I2C EEPROM to store the configuration. The schematic, PCB layout and RP2040 zero code are on GitHub.
Drum Simulator
Based on two copies of the CGS18 drum simulator. One board uses the original R/C values for high and low toms, the other is tuned to give a bass drum and wood block. I ignored the instruction to use 100k trimmers for the resonance; instead by experiment found padding resistor values (R1+10kPOT+R2 = ~100k) so the panel mounted pot at maximum sets the resonance just short of sustained oscillation. This allows each drum to be adjusted from very dry to highly tuned and resonant. I also (at the panel design stage) added a mixer so some or all drums can play through a single output.
Dual Universal Slope Generator
Based on the CGS Voltage Controlled Slope Eurorack with two copies of the PCB behind the panel. I tweaked a few things in the design. By default the circuit can’t be retiggered until the rise/fall cycle is ended, but that’s controlled by just one diode. Including a switch in the circuit for that diode allows the circuit to be retriggered during the fall stage. The CGS circuit already generates a !END circuit using the spare LM3900 op-amp, so I added resistors and zeners to make these outputs available on the panel. Output voltages are set to be compatible with Eurorack by appropriate adjustment of the level trim and changing the zener diode values on the END & !END outputs. The CGS circuit uses DPST switches to enable the exponential rise and fall feature. I changed this to use a DPDT centre-off switch, with the feedback enabled in both ON positions but the 1M resistor to -12V only enabled one way. This gives two different exponential rates. Finally I added (as a behind the scenes dongle) a PULSE output based on a simple op-amp comparator driven by the main OUT signal.
Two Turing Machines each with dual Volts and a Pulses expansion + Vactrol Mix / LPG/MIX
I really like these modules - hence two of them! The second machine has my modified LPG/Mix expander with the Gates/Pulses selector. I’ll be adding a small daughter panel to this to allow control of the vactrol decay time in both Mix and LPG mode. If that works as well as I think it will, I’ll modify the older Vactrol Mix to also allow Mix or LPG mode with variable decay time plus Gates/Pulses switching - it will just lack the three variation switches.
YuSynth Voltage Controlled Panning Output Mixer
Built from the YuSynth design but without the tone control circuitry. I designed the PCBs to allow additional input modules to be added easily and will almost certainly be adding a couple more input channels fairly soon.
I’ve also got to find space to include a couple of commercial modules (a Limaflo MotoMouth formant filter and an After Later Audio nRings) and a panel mounted Korg SQ-1. Cabinet #3 can’t be too far over the horizon…