A little while ago, the idea was discussed to create a comb filter made from several bandpass filters. Unfortunately, due to the way it had to be structured, it was not really possible to automate all of the filters at once in an easy way (not even with a Hydra device).
Later in that same thread, martyfmelb suggested the idea of using bandstop filters instead, to create a kind of reverse comb filter. If you’re just looking for that vowel-like timbre, then this can actually work quite well.
Taking the idea a little bit further… if we stick with the bandstop filters as marty suggests, but then invert the results and mix that all back into the original unfiltered signal, we can take advantage of the way it cancels out in certain areas, and the final result is something pretty damn close to a real comb filter. Best of all, since the bandstop filters are all contained on the same track, we can easily use a Hydra device to control them all at once.
Example - (made in Renoise 2.1):
It needs some more tweaking, and it’s not a totally perfect sound due to the incorrectness of using filters in this way, but it still works kinda nicely.