Build your own noise shaping filters!, Freeware inside Options

[SebastianG]

Hi!

Inspired by this thread -- but also because I like messing around with DSP stuff from time to time .... I wrote two programs that let you design and apply noise shaping filters. Check out my little homepage (screenshot and ZIP to downlad).

I'm kind of proud of the way poles and zeros are controlled. Havn't seen this approach before.
Also, you get to hear the result instantly. Try altering the response while audio is on

Cheers!
Sebastian

PS: I should probably mention that the noise you hear (program "iiirdsgn") is TPDF dithered silence.

PPS: It's likely that you can design better noise shaping filters than those that are supplied. I didn't have accurate equal loudness data available. Filter design tips:
- Try to keep the number of red and blue strings minimal
- Keep the response below ... say +30 dB
- Don't try to approximate equal loudness curves below, say, 1 kHz. If you do, the filters only get more complicated. There's hardly a gain due to the small bandwidth of that region. I intentionally use a linear frequency axis, so don't bother approximation the curves for a very small region.

You may link to *.sos files you created if you think you've designed a really good one.

This post has been edited by SebastianG: Sep 4 2006, 12:57

[Gabriel]

For the beginners, here is an intro to the zeros/poles stuff in z-plane:
http://www.eumus.edu.uy/docentes/jure/docs...eBraindead.html