How good is the Pigtronix EP-2 at imitating the sound of a vibe pedal? [demos]

[RobA]

[...]
Did you feed the JFETs directly or did you replace them with CMOS switches (CD4066)?

I don't remember completely, but I did use the standard JFET's. The general path for all of these types of things was

• Use ATTiny84 16 bit PWM outputs to generate the raw LFO signals.
• Filter and buffer with a second order op-amp based low pass filter.
• Scale the output from the filter to match the range of the original LFO.
• Go from there directly into the portion of the original circuit that the LFO controls.

It was generally straight forward. The idea isn't limited to LFO's either. The same basic format will work for compressors, touch wah/auto filters, and expression pedal control.

[kothoma]

[...]
Did you feed the JFETs directly or did you replace them with CMOS switches (CD4066)?

I don't remember completely, but I did use the standard JFET's. The general path for all of these types of things was

• Use ATTiny84 16 bit PWM outputs to generate the raw LFO signals.
• Filter and buffer with a second order op-amp based low pass filter.
• Scale the output from the filter to match the range of the original LFO.
• Go from there directly into the portion of the original circuit that the LFO controls.

It was generally straight forward. The idea isn't limited to LFO's either. The same basic format will work for compressors, touch wah/auto filters, and expression pedal control.

Understand. You need to smooth the pwm signal quite a bit.
On the other hand, using pwm on a cmos switch requires a) high pwm frequency (best >40kHz) b) post filtering of the audio, so probably no savings here.