Re: Multiple, sequenced delay lines...can it be done?

[Matthias Grob <matthias@grob.org>]

>----- Original Message -----
>From: "Bill Fox" <billfox@fast.net>
>>  The oscillator that clocks the delay line is a VCO.  Modulating the VCO
>changes
>>  the speed at which samples are stored and retrieved from memory, thus
>changing
>>  the delay time.  Of couse, anything clocked out of RAM at a different
>speed than
>>  it was clocked in, will have its pitch changed.
>
>If you use a very short delay and modulate the VCO with a low frequency
>triangle or sine wave, the resulting effect is what we call chorus.  What
>happens is the delayed material is shifed up and down slightly in pitch 
>and
>when mixed with the unshifted signal the result is much thicker
>harmonically.

yes, its how the legendary PCM 42 and other digital delay lines of 
that time work: The memory is digital but the control of it rather 
analog. You dont have the option to jump arround the memory and treat 
loops like samples, and FB does not go straight up to 1, so the loop 
fades sooner or later, but you gain a more natural way to change loop 
time without glitches and a quality of chorus which is hard to 
achieve digitally.

(I love to say that while sitting in PCM 24 creator Gary Hall's nice 
little wooden house in Alameda!)
-- 


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