Main Archive Specials Wiki | FAQ Links Submit Forum

 Digital RIAA equalization filter coefficientsType : RIAAReferences : Posted by Frederick UmmingerNotes : Use at your own risk. Confirm correctness before using. Don't assume I didn't goof something up. -Frederick UmmingerCode : The "turntable-input software" thread inspired me to generate some coefficients for a digital RIAA equalization filter. These coefficients were found by matching the magnitude response of the s-domain transfer function using some proprietary Matlab scripts. The phase response may or may not be totally whacked. The s-domain transfer function is R3(1+R1*C1*s)(1+R2*C2*s)/(R1(1+R2*C2*s) + R2(1+R1*C1*s) + R3(1+R1*C1*s)(1+R2*C2*s)) where R1 = 883.3k R2 = 75k R3 = 604 C1 = 3.6n C2 = 1n This is based on the reference circuit found in http://www.hagtech.com/pdf/riaa.pdf The coefficients of the digital transfer function b(z^-1)/a(z^-1) in descending powers of z, are: 44.1kHz b = [ 0.02675918611906 -0.04592084787595 0.01921229297239] a = [ 1.00000000000000 -0.73845850035973 -0.17951755477430] error +/- 0.25dB 48kHz b = [ 0.02675918611906 -0.04592084787595 0.01921229297239] a = [ 1.00000000000000 -0.73845850035973 -0.17951755477430] error +/- 0.15dB 88.2kHz b = [ 0.04872204977233 -0.09076930609195 0.04202280710877] a = [ 1.00000000000000 -0.85197860443215 -0.10921171201431] error +/- 0.01dB 96kHz b = [ 0.05265477122714 -0.09864197097385 0.04596474352090 ] a = [ 1.00000000000000 -0.85835597216218 -0.10600020417219 ] error +/- 0.006dB