LowPass Filter design
Filter Question
For a simple Onepole LowPass filter made with a history and a linear interpolation function, what's the best way to implement resonance?
out = in × (1 - freq) + previous_out × freq
resonance from interpolation?
It's a simple filter design, it only has a mix, a history and a parameter to control the frequency response. I was asking how could I make something based on this design and make it a resonant filter.
Well, the best results I had was stacking four of these simple low pass filters and then creating a feedback loop from the last order to the first order. It sounds like resonance, but it's not really well tuned and it doesn't sound good. I was asking what was the best way to achieve this or at least some principles I should have in mind.
I don't really know what I'm doing so there's probably a better way to do it.
I tried replicating the set up you mentioned and I had some much better results when I Inverted the feedback loop.
I also used a [tanh] to avoid crazy amplitudes which let me multiply the feedback amplitude by 3.
That starts to sound like a resonant filter to me.
while interpolation does almost the same than using poles and zeros with 3 db, its properties are different.
to the suprise of many music dsp people there are butterworths with resonance, but normally you need at least 2 poles two zeros (biquad, multiple examples for gen~ available) for a filter with dynamic Q, or alternatively a ladder filter.
i don´t know if there is also an SFV kernel example for gen~ around? this could be the closest for what you are looking for.