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The motherboard is expected to provide a 0 to +2.048 volt cutoff frequency CV signal. The plug-in boards are designed to sweep through their entire range with this range, with 0 volts mapping to the lowest cutoff frequency (usually around 20Hz) and +2.048 volts mapping to the highest cutoff frequency (usually around 20kHz).
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- Inject a 30Hz square wave onto the signal input while monitoring the signal output.
- Turn the cutoff CV and feedback CV signals all the way down (set them to zero volts).
- Adjust the center trim so that the signal just dissapears.
- Remove the signal input.
- Turn the cutoff CV to around 1/2 way up and turn the feedback CV all the way up.
- Adjust the feedback trim until self oscillation occurs.
- Turn the cutoff CV signal all the way up.
- Adjust the depth trim until the frequency of the self oscillation is around 20kHz.
- Sweep the cutoff frequency up and down and readjust the feedback trim as needed to get reliable self oscillation over the desired range. Note that some filters will not self oscillate over their whole frequency range.
- Now reinject the signal and listen to the filter while changing the cutoff and feedack CV signals. Readjust the trimmers to taste if desired.
Board | breadboarded | schematic | pcb layout | built and tested | documentation |
---|---|---|---|---|---|
2164 phasor | ☑ | ☑ | ☑ | ☑ | ☑ |
2164 LPF | ☑ | ☑ | ☑ | ☑ | ☑ |
2164 SVF | ☑ | ☑ | ☑ | ☑ | ☑ |
arp 4072 LPF | ☑ | ☑ | ☑ | ☑ | ☑ |
CEM3320 LPF | ☑ | ☑ | ☑ | ☑ | ☑ |
haible 2040 LPF | ☑ | ☐ | ☐ | ☐ | ☐ |
haible tau phasor | ☐ | ☐ | ☐ | ☐ | ☐ |
Late MS20 VCF | ☑ | ☑ | ☑ | ☑ | ☑ |
minimoog LPF | ☑ | ☑ | ☑ | ☑ | ☑ |
mutron 3 SVF | ☑ | ☑ | ☑ | ☑ | ☑ |
optical phasor | ☑ | ☑ | ☑ | ☑ | ☑ |
SSI2140 LPF | ☑ | ☑ | ☑ | ☑ | ☑ |