I am currently building a Reverb that needs to fit on a DSP. I am using the model proposed in this link https://ccrma.stanford.edu/~jos/pasp/Freeverb.html.
It involved to create some Feedback Comb-Filters with high orders (more than 1000). For that I use a 2nd-order section IIR filter (IIRSOS) integrated in my DSP. I am using the Matlab function "tf2sos" that takes numerator and denominator of the Transfer Function (TF) of the desire filter and create a matrix of Second Order Section (SOS) coefficient. With this coefficients, I can make what I want.
Problem : for high filter orders (arround order 200) the "tf2sos" function appears to be totally unstable. However the Matlab object called dsp.IIRFilter that use also 2nd-order section IIR seems to handle it :
Impulse response for order = 200 : Impulse response for order = 1500 :
On the 2nd picture you can see that the filter with the tf2sos coefficients is going totally wrong. Does someone knows how I can get a functional coefficient matrix for orders like 1500 ?