Barberpoles and other things

Ingo Debus debus at cww.de
Mon Jan 19 11:08:01 CET 1998


Stopp,Gene wrote:
> Central to any barberpole device (other than low-beat frequency shifters
> and similar effects) is a multi-phase ramp-and-triangle CV generator. (I
> think that the term "Shepard Function Generator" is the name for this,
> right?) The ramps are used to control the rising effect (VCO, phaser,
> VCF, etc.) and the triangles are used to fade in and out the audio for
> each effect.

I've just "emulated" a barberpole phaser with a Ensoniq DP/4 effects
processor and a sequencer program that serves as 8-output-LFO. The DP/4
has four independent effects processors (called Units). I connected them
in parallel and set all to "Phaser". Since the DP/4 has no global LFO
for all processors, I had to MIDI-control the "Volume" and "Center"
parameters of the four phasers with the sequencer. The result sounds
very much like Juergen described:

>One "sweep" starts
>at lof frequencies, rises, and fades out at high frequencies. Then
>another one starts at the low end. Sounds like sawtooth modulation,
>only without a reset glitch. 

Anyone interested in the sequencer file (MIDI file or Logic song)?
It sounds interesting with VCFs (high Q settings) instead of phasers,
too.


> To the American ear, a lot of German nouns seem to describe the object
> they refer to in a very descriptive, almost humorous, way. For example,
> "Klangumwandler" sounds a little like "Gong Warbler" or "Klang Wobbler"
> or something which implies a thing that is both inharmonic and
> constantly moving. Hence the name has a certain charm when applied to a
> frequency shifter. (Sadly most of us over here have little or no
> exposure to other languages, myself included.)

There seems to be a misunderstanding. It is "Klang-Umwandler", not
"Klangum-Wandler" ;-)

Ingo





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