[sdiy] Analog Delay Lines (was) [common acronyms?]

[harry]

Unnnh... Yeah thats what i meant ;^P

Well I'm right about the phase shifter (allpass) and that the Hammond
vibrato
IS actually a delay line... so do I get a 75% ?

Now... where is the Hammond delay tuned (in frequency)... ???

H^) harry

Don Tillman wrote:

>    Date: Mon, 08 Oct 2001 22:19:36 -0400
>    From: harry <harrybissell at prodigy.net>
>
>    An allpass filter network could also introduce delay... thats how
>    phase shifters and old (Hammond) vibrato units work...
>
> Hey Harry,
>
> Perhaps we're running with different terminologies, but I believe an
> allpass filter and the Hammond delay are fundamentally different
> beasts.
>
> An allpass filter, one with mirror image poles and zeroes, only offers
> something approaching delay over a small frequency range.  For
> instance, the delay at the high and low extremes is zero.
>
> But the Hammond delay is different -- it's an LC model of a
> transmission line, it doesn't have mirror image poles and zeroes, and
> it's a pretty accurate delay over a wide frequency range.
>
>  -- Don
>
> --
> Don Tillman
> Palo Alto, California, USA
> don at till.com
> http://www.till.com