[sdiy] SPICE simulations of Jurgen's favorite filter

[Grant Richter]

I got around to simulating the resonant tank from the Korg PS3100/3300
"Triple Resonator". Some results below. Drawing dated 23-2-77

Anybody have the link for the original Korg drawing?

Input highpass (IC11):
-3 dB @ 123 Hz

Needed because of the increasing gain of the resonators as the LEDs go off.

Resonant tank (VTL5C2/2 and 1/2 1458) Sharp peak bandpass

Vactrol (both legs)
resistance         Gain/Frequency

400K               1.75 dB @ 60 Hz
100K               2.1 dB @ 230 Hz
10K                0.49 dB @ 2.4 kHz
1K                 -5 dB @ 20.89 kHz

For 100K Vactrol resistance

Yellow  200 Hz
Green   240 Hz
Blue    280 Hz
Gray    400 Hz
White   480 Hz