Re: [sc-users] Re: Resonz x Ringz (gain issues)

[Alexandre Torres Porres <porres@xxxxxxxxx>]

so it looks like the formula is something like: y[n] =  a0 * (x[n] - x[n-2]) + b1 * y[n-1] + b2 * [yn-2];

pretty close to the [reson

2014-12-20 22:08 GMT-02:00 Julius Smith <jos@xxxxxxxxxxxxxxxxxx>:

At 02:54 PM 12/20/2014, Alexandre Torres Porres wrote:

HI, meanwhile I digest and sort about the ring decay time, something called my attention. By looking at the code.

"y0 = ZXP(in) + b1 * y1 + b2 * y2;
    ZXP(out) = a0 * (y0 - y2);
    y2 = y1;
    y1 = y0;"

I can't see how it is a two pole and two zeros filter. I only see feedback coefficients (b1 * b2). What am I missing? Or is it a two pole with no zeros?
The term y0-y2 straddles two samples, giving a zero at z=1 and another at z=-1, as needed for the constant-peak-gain property.

- Julius

Julius O. Smith III <jos@xxxxxxxxxxxxxxxxxx>
Professor of Music and, by courtesy, Electrical Engineering
CCRMA, Stanford University
http://ccrma.stanford.edu/~jos/