special effect

[Magnus Danielson]

From: Jeroen Proveniers <J.Proveniers at orga.nl>
Subject: special effect
Date: Tue, 22 Aug 2000 08:32:49 +0200

> Hello,

Hi!

> A few years ago I read in an article about some weird effect, probably named
> after its inventor, that gives the illusion of an endlessly rising tone. It
> worked by 'cutting and pasting' higher harmonics to lower. I'm curious how
> that sounds and how it's actually made.

It's the Shepards tone. It it the continous form of a little game that Bach
played with discrete notes many, many years ago. The Shepards tone consist of
a number of sines (8 has occured) spaced evenly out 1 octave away. These tones
either rises or falls. The amplitude of a sine is raised as the sine is
approaching the middle, and then the amplitude is reduced as it passes away
from the middle. Modulation wise you have a sawtooth for oscillator CV and a
triangle (with the same period time, in sync with each other) as the VCA expo
CV signal. Paia at least used to have a kit for creating these waveforms.
Also, as I recall it, the description for it also said alot about the theory.

I don't have a sample around but if you where here I would play a test CD
containing it.

Cheers,
Magnus