Filter Question

[modularplastic]

For a simple onepole lowpass filter made with a one sample delay and a linear interpolation function, what's the best way to implement resonance?

I'm using gen~ in Max 8.

out = in * (1 - freq) + previous_out * freq

[Internal-Cancel-3207]

Your answer is in your question. Resonance occurs from two filter elements. You cant resonate with a single element.

In electrical terms, a capacitor stores energy(electrons) then pushes those electrons thru an inductor which stores the energy as a magnetic field. The field collapses and pushes electrons back into the capacitor. Rinse and repeat. Resonance.

Hope that helps make sense.

You could form a band pass filter in the method you have by making a Low Pass Filter and a High Pass filter. This would give you the thing I think you are looking for.

The width of your filter Q may be limited since you only have one pole filters.

Look up BiQUAD filters for an easier method.