"Un*vibing": how to calculate staggered caps

[puretube]

[TUBE]

So you always wanted to know, where these strange cap-values come from?
They come from one of the over 100 patents issued to Robert B. Dome;
yes, the inventor of the famous Dome-filter;
Without Dome, we wouldn`t have had modern broadcasting, TV, and telephoneing that easy and early and good.
No AC30-Vibrato, Bode/Moog frequency-shifter, and a bunch of other nice FX...

http://v3.espacenet.com/origdoc?CY=gb&LG=en&F=4&IDX=US2566876&DB=EPODOC&QPN=US2566876

Although this file actually is intended to teach how to get two signals 90 degrees apart,
it is the first treat on spreading phase-shift evenly through the spectrum (in each of the 2 channels).
This dispersion principle is what the "un*v*be"- uniqueness is based on,
and what the great organ-people have used years before that unit, ...with tubes.


[this rounds up today`s installment of: "GET EDUCATED"]

[radio]

Enlightening:o

Thanks a Ton


Greetings JMErnzer

[Eb7+9]

Although this file actually is intended to teach how to get two signals 90 degrees apart,
it is the first treat on spreading phase-shift evenly through the spectrum (in each of the 2 channels).

This dispersion principle is what the "un*v*be"- uniqueness is based on,
and what the great organ-people have used years before that unit, ...with tubes.


[this rounds up today`s installment of: "GET EDUCATED"]

hunh dispersion ... please explain ...

... spreading phase-shift evenly through the spectrum

I think you better take out a pencil and a sheet of paper and figure out what the vibe does using first order RC mixing - specifically, in terms of phase summing ... you'll find the last thing it does is shifts evenly through the spectrum ...

The cap arrangemenrt of the Univibe is briefly explained at my page - it is meant to simulate the phase shifting of two frequency bands ... like the horns on top and the baffle on the bottom of a Leslie ... by staggering the stage cutoff frequencies part of the signals get phased by almost 360 degress (due to losses) and others less as the all-pass transition frequencies move up and down with light ... notice how the vibe cap values are a decade apart - except for the first two stages which are off by a little - this gives it away ... the Resly-Tone cap values on the other hand are linear in ordering and produce a different effect ...

If you study first order circtuit analysis you'll find simple RC low-pass and high-pass circuit have a phase shift transition zone that starts a decade below the cross-over frequency and ends a decade above - most people ignore the phase response part in Bode plots - but in phasors it's kinda relevant ...

... in the Vibe the two first consecutive stages are set so that second stage's phase shift curve starts where the first one stops and same with stages 3 and 4 ... it jumps right out at you if you look at it that way ...

That's the "key relationship" that is preserved in my Small-Stone and MXR 45/90 univibing mods ...

this paper has nothing to do Vibe cap values ... a moins que mon Tabarnaque de Francais est devenu si terrible ...

... we don't need NO education :wink:

[puretube]

hunh dispersion ... please explain ...

... spreading phase-shift evenly through the spectrum

:wink:

it`s the same what you prefer to explain like this:

...have the effect of providing linear phase shift over two decades of frequency for each pair ...