Smooth overdrive to mellow out resonant filters

[Digital Larry]

I've come up with some nice resonant filters that quite easily get out of control (too much gain) when the Q goes up. Now this is not necessarily a bad thing. I'm looking for a good smoother to run them into to avoid hard clipping. I've tried the "overdrive" code and it seemed to work OK.

I also saw some examples of someone using the "cube distortion" for a similar purpose. I've tried the cube distortion and I cannot make it noticeably distort with any of the test signal that easily distort the other dist blocks I've tried (overdrive, t/x, "distortion"). I've noticed others have had this same observation. I could try a couple SOF -2.0,0 in front of it.

Anyay back to the filters, anyone have any experience with slamming the signal into the rails on purpose but using something like this to smooth it out and limit the resulting aliasing?

[slacker]

The cube distortion is very subtle, it's works though, it clips at 2/3 the supply so a couple of volts, it needs a loud signal to make it clip.
I've used it to limit the level when maxing the feedback in a delay, the signal would hit the rails causing the clipping LED to flash, adding the cube distortion prevents it hitting the rails.

[Digital Larry]

I was just over at musicdsp.org and found this article on a simulation of a 24 dB/oct Moog filter:

http://www.musicdsp.org/showArchiveComm ... chiveID=24

Uses a "sigmoid" function for a soft clipper at the output. Looks like a similar concept!

Code: Select all

//Clipper band limited sigmoid
y4 = y4 - (y4^3)/6;

Thanks.

DL