New Filter Designs

[Sean Costello]

Grant Richter wrote:
 
> The circuit produces the sharpest comb filters that I have heard.
> The sound is very similar to a flanger or phase shifter.
> While the original design used an ultrasonic clock,
> by far the most interesting sounds are produced by
> clocking it in the audio range. It sounds really good
> with a rhythm box driving a sequencer controlling the
> clock frequency.

Could you provide a few more details about the sound? Does it have the harmonic
peaks of a flanger, or the non-harmonically related peaks of a phase shifter?
How wide of a sweep can you get out of it? Did you have to modify the clock to
get it into a useful range? Can you put an x^3 circuit in the feedback loop to
make an Ueda attractor flanger phaser? ;)  (BTW, somewhere in Electronotes is a
reference to a frequency tripler that uses only two transistors, which might be
a useful, cheap substitution for the two multipliers you would otherwise need
for an x^3 term.)

Looking at the circuit, it seems very cool. It certainly seems like a nice
alternative to a BBD-based flanger, in that it uses VERY common parts. I wonder
if it would be useful for a stomp-pedal...

Sean Costello

P.S. Anyone know of any schematics online for other switched capacitor filters
or phasers? I think the ADA Final Phase used a switched capacitor design.