Oscillating stationary/tunable comb filter for drone

[DerpyGrooves]

I'm looking for something similar to the tone matrix effect from the EHX Electric Mistress, but far more pronounced. Ideally, I'm looking for like, almost a dynamic tanpura/sruti box sort of sound. Any well-known circuits that provide such functionality in a musical way? Obviously, I'm concerned about the spacing of the comb, that seems like it would probably matter.

[ashcat_lt]

Don't know if it will do what you want, but what you've asked for is a phase shifter with a CV knob in place of the LFO, with positive feedback.