The customer wanted a Moog Ladder filter. I chose to use the YUSynth MiniMoog VCF PCB as the size would fit behind a double wide PAiA panel and I could adapt it to run on the +/-9V power supply. I made the panel using 1.5mm anodized aluminum with the print graphics feature from FrontPanelExpress. I added a attenuators for the input and CVs and modeled the graphics similar to the 4730 Multi-Modal filter. A real Moog 904A listed for $250.00 in 1967 and ~$500.00 in 1973.
The YUSynth PCB is a perfect width for a 2wide PAiA panel.
Resistor changes for +/-9V operation
Resistor changes for PAiA levels
I made brackets similar to the PAiA and mounted the PCB to the panel. I added a 2.2 µF output capacitor with 100K bleed resistor for operation with the 2720-1 VCA since those inputs must be AC coupled.
I adjusted the output level so self-oscillation was 1V pk-pk.
I then adjusted the input level so with some resonance the output was just a bit over 1V pk-pk.
A bit more resonance drops the output level just a bit to under 1V pk-pk.
Maximum resonance is quite wild.
With no resonance the output level is hot at 2V pk-pk.
Adjusting the input attenuator to 50% results in a 1V pk-pk output.