Shepard Tone Generator

Phil Maguire

Hi all,

Had a quick search around the site and forum but not found much that's helpful.

I'm putting together a simple Shepard tone generator, but I don't understand the maths, beyond having each oscillator driven by a proportionally out of phase phasor. What I have so far sounds ok, but you can hear quite obviously when each ramp ends and begins. I've based it on this: https://cycling74.com/articles/risset-glissandos-and-strange-loops-2/replies/1

Any tips? I'm not sure I've got the right arrangement of starting frequencies. Any maths corrections/additional maths that I may need, can someone explain in very plain English?

Thanks!

Max Patch

Copy patch and select New From Clipboard in Max.

Martin Beck

I am not not sure about the usage of [cos~] for amplitude control.
Referring to http://www.doepfer.de/a100_man/A191_man.pdf
and https://en.wikipedia.org/wiki/Shepard_tone
there seems to be some other signals for driving amplitudes.
You may try [tri~] waves and connect a [spectroscope~] to the sum output and match this with this one https://en.wikipedia.org/wiki/Shepard_tone#/media/File:Shepard_Tones_spectrum_linear_scale.png .

Edit: You can also have a look inside the Beap module RISSET OSCILLATOR, just hover over the left side until the triangle appears and select "Open". The [poly~ mro_sin @voices 1 @steal 1] contains the basic signals.

Phil Maguire

Thanks Martin! The Beap module is just what I need.