Using comb filters to create other effects

[dubathonic]

I’m wondering if anyone knows of background resources I can check out as I learn about comb filters. I ask primarily because of a new machine included in the MD OS that @JustinValer spearheaded, but I’m posting to the general forum as I’d expect the information might help users of other instruments.

In particular, the manual for the new OS has this to say about the new machine:

“NFX-UC packs 2 universal comb filters into one machine, and can be programmed as various effects, such as chorus, flanger, vibrator, stereo imager etc.”

… I’ve never used comb filters to create any of these effects and I’d be interested to learn. All resource suggestions welcome, including threads on this forum I have overlooked. Thanks in advance!

[Lauli]

So a comb filter is usually achieved by mixing the original signal with a veeeery short delayed version of itself. The longer the delay, the more teeth are in the comb. The higher the feedback on the delay, the “sharper” the teeth.

By applying an LFO to the delay time, the number of teeth sweeps up and down. Depending on how you’re sweeping (delay length, LFO speed) you either get chorus or flanging. I don’t know the exact differences but… if it sounds like a jetplane it’s a flanger, if it sounds watery, it’s chorus
To get a vibrato effect, you’d fully cut out the original source and only listen to the delayed signal.

To get a stereo imaging effect you could do all sorts of funny stuff, there’s no clear cut rule here I guess. Just treat the left and right channels differently.

But I think the real fun begins, when you don’t just do LFO sweeping on the comb filter, but more complex waveshapes, or very precise values. I love the metallic type of resonances you get when you finetune the combfilter to specific musical notes.