Forums

Graphic Equalizer

Started by Stacy November 5, 2007
I want to implement a graphic equalizer in S/W.
I assume it is a bunch of bandpass filters with boost/cut at their
respective frequencies.

Has anyone else done this or know of any links?

for a parametric EQ (tuneable center freuquency and quality factor), see

http://www.musicdsp.org/files/Audio-EQ-Cookbook.txt

-mn

On Nov 4, 11:30 pm, "Stacy" <stacy2003_yo...@yahoo.com> wrote:
> I want to implement a graphic equalizer in S/W. > I assume it is a bunch of bandpass filters with boost/cut at their > respective frequencies. > > Has anyone else done this or know of any links?
Look for: Digital Stereo 10-Band Graphic Equalizer Using the DSP56001 Application Note APR2/D, Motorola Inc. I can't find it on the Motorola or Freescale web site, but there seems to be a copy available here: http://www.harmony-central.com/Computer/Programming/
On Nov 5, 3:53 am, "mnentwig" <mnent...@elisanet.fi> wrote:
> for a parametric EQ (tuneable center freuquency and quality factor), see > > http://www.musicdsp.org/files/Audio-EQ-Cookbook.txt >
also, if the word width is wide (and i think 32-bit fixed is pretty good, and the native double-precision is more than wide enough), then you can implement the Graphic EQ as a cascade of the parametric EQs (i might call it "peaking EQ" since, i think the language supports the shelving filters as a class of "parametric EQ") with fixed frequencies equally spaced apart in log frequency (and with the parametric EQ bandwidth nearly equal to that spacing). this is an alternative to the parallel BPF each centered at these fixed frequencies with gains attached to each. i believe the parallel BPF structure gets less noise (most certainly if the untruncated double-precision output of each BPF is added before rounding) then the cascade structure. this is why i tossed in the word width caveat. r b-j