[sdiy] Digital Delay - smoothly varying the delay time

[Tom Wiltshire]

Thanks Florian, this is very interesting to know.

I'd like to be able to modulate the delay time if I get that far, so I'm avoiding the "crossfade between two read pointers" techniques, and looking more at the "speed up/slow down" techniques.
I was having a think about what's involved last night, and I don't think it's as hard as I thought at first. I was over-thinking it a bit. Still, doing a decent job isn't straight-forward - but when is it ever?

Tom

On 20 May 2016, at 10:15, Florian Anwander <fanwander at mnet-online.de> wrote:

> Hello Tom
> 
>> Do commercial delays work like this? Do you notice a delay when you twiddle the delay time?
> I'd say out in the commercial wild all variations you mentioned exist.
> 
> All old Roland Delays (SDD-1500, SDD-2000, ...) simply muted the delay while changing the delaytime.
> 
> Early Korgs use up/down buttons and delay the variation. The SDD3000 can count up/down in 1ms or 10ms steps. I estimate that the change rate is at 5 steps per second. It takes quite long to come from 10ms to the max delaytime of 1024ms. There is no hearable artifact.
> 
> My Solton DDL-1500 worked similar, but the change rate ist faster. I think they decrease the frequency range of the delayed signal(!) with an filter in the output while changing the delaytime, so no artifact noise comes through.
> 
> I own two Vestakozo DIG-20's which have hearable zipper like artifacts when the delaytime is varied quickly - I love them that for (but those Vestzakozos are pure electronic punk anyway).
> 
> Florian
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