Re: Zero Delay Feedback Filter
Posted: Thu Mar 03, 2016 1:02 pm
stw wrote:This is a quote from martins post earlier in this thread:martinvicanek wrote:For even order N we have i = 1, 2, ..., N/2 biquads with
Q_i = 0.5/cos(alpha_i)
where the alpha_i are spread uniformly over (0,Pi/2):
alpha_i = (i - 0.5)*Pi/N
You can obtain the Q values from this, e.g :
1 biquad: i=1; N=2; Qi = 0.707
2 biquads: First: i=1; N=4; Qi = 0.541 Second: i=2; N=4; Qi = 1.307
...
or take it directly from the various filter examples martin already posted!
Thank you very much, stw.
I was afraid of getting a quite technical answer. The thing is, I don't know what all of this means. There's the zero delay feedback filter, and it outputs lowpass/hipass/bandpass/etc. There's an input labeled "Resonance (>0)". I would like to have a value for this resonance input that is equivalent to "no resonance".
I don't see any Q there. I don't know what biquad means for this filter. I don't know what N means. I'm totally lost here.
Is there no way to have an exact value for exactly this zdf filter with all its outputs? I don't even dare to ask, what value would refer to Resonance = 127/100%/1.0 on other synths...