shepard generator

[David R Ryle]

Dr. Schmitz wrote;
Am i wrong ? I think, the ever rising glissando needs two phase shifted
oscillators : one saw (8 outputs, each 45 degree shifted) and
additionally
one TRI (same as saw).

(TRI could be generated from the SAW, so this wouldn't be THAT problem)

SAW serves as input for the VCO and TRI as input for the VCA.
Otherwise you will hear the tune jump of the vco's.
By the way : 8 VCO's and 8 VCA's, together with the TRI/SAW shepard
generator. A lot of work.

Are there wav-files in the net, containig an example of
the "ever rising glissando" ? Before building up all these things
i would like to hear it.


 Yes, I too would love to hear a MIDI file or WAV file of this. (I think
Terry Bowman ka4hjh at gte.net says he might be able to find it if you are
interested.) I'm not so sure how you could loop this with any real
results without some glitching between loops, but if it could be done it
might make an interesting background 'Erik Satie' wallpaper effect for a
web page or something.
 The use of triangle and sawtooth (or ramp) waveforms as inputs to
oscillators and amplifiers would be an excellent idea, and is alot like
the idea mentioned by John Simonton, if the LFOs used were slow enough,
and stable enough, as well as had the capability of being 'phase
synched' somehow. This would actually be more like a true analog
treatment of the 'Barber-Pole' effect, but harder to do right in my
mind. (Although Martin Czech may have some good ideas going for this...
)
 The way that Simonton devised is a much more stable way of achieving
this through the use of 'digital' circuitry via clocks, and counters.
But it seems it has only has a stepping type of CV output to the
oscillators and amplifiers, instead of a glissando type of CV. The
advantage to me is that the 'Chromatic' effect is much stronger than the
'Atonal' effect using glissando CV.
 Maybe one of the DIYers would be interested in building and sampling
the two effects and putting them on their web page for the rest of us to
hear.
 I also think the Simonton design would make a wonderful stand-alone
synth unit, or as a self-contained modifier to use with your synth.
(provided the CV output was scaled exponential or linear for your
particular use.)
 Once again the link for the PAiA, John Simonton SHEPARD FUNCTION
GENERATOR is;
http://www.hyperreal.org/music/machines/categories/do-it-yourself/Paia/images/

 Enjoy!
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