From sdiedrichsen@b-three.de Thu Apr 07 01:43:11 2005
Subject:Re: Chorus/ vibratoeffect Way to go. - a divergent view ITS ON!!!


Am 06.04.2005 um 18:49 schrieb Kevin:

> In regards to this whole thread, glad to see such a lively
> discussion.  What I did not take into consideration was the
> possibility of cutoff frequency being way out beyond the generator's
> range, which nearly nullifies the discussions of phase shift. 

Surprisingly, the cutoff frequency of the delay line is @ 6 kHz. You
have a ripple below the cutoff frequency combined with a soft roll-off.
But the phase shift starts in the bass region.

>
> Using a series of LC networks to create a delay line was quite
> innovative considering the space they had to pack it into and the
> (circa '60s, I think) technology they had to work with.
>
They started the vibrato much earlier. The Hammond BV and CV, which
came out 1946, were the 1st organs with vibrato equipment.
The concept of passive delay line is very old and comes from the
telecommunications world. In fact it is just a model of a waveguide
with its resistance Z = sqrt(L' / C').
Here's a good reading on passive delay lines, since even today there
are applications for this old technology_
http://www.rhombus-ind.com/dlcat/app1_pas.pdf

Best,

Steffan

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