Looper's Delight Archive Top (Search)
Date Index
Thread Index
Author Index
Looper's Delight Home
Mailing List Info

[Date Prev][Date Next]   [Thread Prev][Thread Next]   [Date Index][Thread Index][Author Index]

Re: Claude Voit's See What--Ipoulkapek--I Can Play It--I Can't Pronounce It

You guys are talking about the "Shepherd Tone", from Roger (?) Shepherd's research on psychoaccoustics many years ago. I've got a "Shepherd Function" lfo as part of my custom-built analog modular synth. Basically it has 8 triangle wave outputs, at 45 degrees phase difference to each other, and 8 corresponding sawtooth outputs that can either be rising or falling. To make the classic barber pole effect, one controls the vco's frequencies with the sawtooth waves (always rising or falling pitches) and amplitude (by vca) with the triangle waves (each oscillator starts out silent, fades up to a max volume at halfway up the sawtooth, then fades out in volume by the time the sawtooth wave resets). By having layers of these tone events (8 in this case- could be more) overlapping, it creates the impression of an eternally rising or falling tone. I think Harald Bode created a phase shifter that worked this way; I've always wanted to know more about the history and specs of *that* product...


Tim F

PS that lfo is great for quad panning!

In a message dated 8/29/03 6:05:59 PM Pacific Daylight Time, relaydelayband@earthlink.net writes:

Oh Yeah, there's one on the SPX 90.
Thanks for the play by play.

--- Relay <relaydelayband@earthlink.net> wrote:

>How does one do [a 'barber pole'] ... on
>either the EDP or Repeater?

There might be many ways, but the easy answer (and one
that would work with ANY kind of looper of sufficient
delay time) would be to post-process the loop.

1) Open your loop.
2) Fade in a rising or falling glissando (or
speed-change an old-scool delay sample-and-hold loop
INTO your other looper), then fade out.
3) Close the loop. (At this point the glissando will
be discrete and separated by a moment of silence)
4) (Optional) Overdub more glissandi onto the loop and
over the loop 'seam'
5) Post-process the loop through boatloads of delay.

Psychoacoustic caveat: whilst rising 'barber poles'
are figuratively uplifting, falling ones are kind of a
spiral downer...