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Shepard Tone Generator in Frac?
MUFF WIGGLER Forum Index -> Fractional Rack Modules  
Author Shepard Tone Generator in Frac?
alesauskas
Just out of curiosity, I see that PAIA used to make a shepard tone function generator, the EK-9? It doesn't seem like it is available any longer, and I was wondering why, since PAIA seems to be going strong still. Also, I know Buchla has his Barberpole module with possibilities of using this as CV elsewhere in the system, which seems really interesting. Any other shepard type modules in Frac out there in the past or present? I know it is a bit of a one trick pony, but the CV option seems like it'd be fun.
chamomileshark
I can't think of any.
monstrinho
The EK-9 schematics are available here;

http://www.midimanuals.com/manuals/paia/ek-9_shepard_function_generato r/lab_notes/

It looks interesting. Somebody correct me if I'm wrong, but I don't see any rare/unobtanium parts on the parts list. Could be a fun project if someone wanted to make some PCBs for it.
werock
I think this type of module is generally thin on the ground, regardless of the format.
alesauskas
I agree it seems like a straightforward DIY build, would be nice to have the option. It could be no one produces it because the reality of it doesn't hold up to it's conceptual potential, but a kit price might make it more worthwhile...

Guess I'll just have to get into Buchla if I want to explore this option more, at least in the analog realm very frustrating . I have played around with a shepard generator made by CNMAT from Berkeley in MaxMSP, although the illusion in that one isn't quite complete as the reset is obvious. Also have heard Reaktor has a seamless one, and have also made one in Ableton with prerecorded tracks, but I want that CV option! sad banana
drumsofd00m
Some theory:

you might want to check out modules that can be used as quadrature LFOs, such as the ZerOscillator. For the "traditional" Shepard or Risset tones in a VC system you'd need ten complete paths of VCO, VCA, LFO (each with tri and ramp outs). So it's going to be a pile of gear whichever route you choose.

To emulate the required multi-phase CV source, I think you could use an array of MiniWaves as phase shift transform functions if you programmed an EPROM for each with simply a ramp that is delayed by the degree required for each octave's subsystem. You'd only get 8 bit quantized CVs though, and good luck buying or assembling ten MiniWaves ;)
alesauskas
That's funny this was posted right before two free Mini-Wave panels went up... hmmm..... I do like the idea of using wavetables to achieve this sort of CV option, but the price factor will keep it in the realm of speculation I think

Found this recently on Grant Richter's site:

http://www.musicsynthesizer.com/Circuitry/shepard.html
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