I'm currently using a 2nd order peaking filter for doing EQ on a project. As part of that I need to calculate the IIR coefficients to send to the DSP and I'm having problems. Currently the calculations I'm using are the ones from the spreadsheet that I have attached however when I compare the values that are calculated using that to the values the SigmaStudio calculates there is some discrepancy. Through some testing I have found that the alpha value that is calculated from the spreadsheet seems to be completely wrong after a frequency of about 4kHz.
I can't seem to find any other equations for alpha other that the sin(omega)/2Q that the spreadsheet uses and was wondering whether that value is correct. If not, what alpha value am I meant to be using.
I've attached the spreadsheet that I'm using for the calculations along with the one I have been testing with if that is useful.
Any help on this would be greatly appreciated.