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

sorry, I hate when I accidentally hit the shortcut to send a message in chrome...

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 pd/max's [reson~] object formula, which is a resonator, and is:
y[n] = g * (x[n] - r * x[n-2]) + c1 * y[n-1] + c2 * y[n-2]

it should most probably be the same thing...

Well, let me get back to figuring out the rest.

thanks!

2014-12-21 9:54 GMT-02:00 Alexandre Torres Porres :
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 :

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;
Â Â Â  ZXP(out) = a0 * (y0 - y2);
Â Â Â  y2 = y1;
Â Â Â  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/