[sdiy] How does resonance work?

[Jack Jackson]

Recently I've started building the Jupiter 8 filter using the IR3109 and also with discrete OTAs. I couldn't get the resonance to work, so I looked at the other implementations of the 3109 in filter circuits. I started wondering:

Is resonance as simple as a VCA in the feedback path of the gain cells?

I know that resonance is an increase in emphasis of the cutoff knee of the filter; the highest frequency you can hear from the LPF. So, although the fundamental frequency of the signal passing through it might be quite low you hear the whooshy self-oscillation as a higher freq.

Please correct/educate me.

Thanks,
Jack