[sdiy] BBD help

[Shokwave]

----- Original Message ----- 
From: "Harry Bissell Jr" <harrybissell at prodigy.net>

> <harryrantmodeon>

> 5) DIGITAL delays are cheap today as well... Princeton
> Technologies makes the PT- (something help me here)
> which will do the delay better than most BBD circuits
> at the same cost.
>
> 6) BBDs were the 'only' sub for tape echo in their
> day... but that day is long past.  Digital delays are
> going for cheap new, and cheaper used.
>
> so if you want to explore the BBD for educational
> purposes, go for it. If you want an audio delay of any
> quality... there are better faster cheaper ways to go.
>
> </bbdrant>

Ok. Here's what I'm looking to do - maybe with that info someone can help me
determine the best way to go about it, and my examples of 1-50ms were way
over exagerated:

I want to simulate a SHORT delay, at LOW FIDELITY. How short? Why low? Well,
I started with the premise that guitar feedback is related to transmission
delay (cord length + amp circuitry) and a low-fidelity interaction between
sound waves and guitar strings. Now, I'm not just thinking of using this as
a guitar feedback simulator circuit to be built into a tube amp simulating
distortion unit; I think it might sound good for all sorts of sounds I
create in my modular as well. Besides which, I already own a real tube amp.
I am thinking it might make a nifty headphone amp, or just a neat guitar
stompbox, but I'm not aiming for any one thing here, just playing with a
concept. As a result, I might want more delay than is in a real
guitar->amp->guitar feedback loop, but nowhere near enough that the delay is
really a chorus effect.

So...let's say I need 5ns-5ms of grungy delay...what is the simplest,
easisiest, and/or cheapest solution? Or 10ns-1ms? etc. Are there certain
values we can plug in there that yield optimally easy/cheap solutions?

Aside from all that, another use of extremely short delay might be to design
a circuit that emulates transformer/rectifier "sag". In that case, you might
use a HIGH fidelity delay, and run it at full volume...but process the
original signal (split off before delay) and mix it in after potentially
nasty heavy filtering. Sort of a reverse BBD :)

I have this feeling that at short enough durations (measured in ns), there
is a solution that doesn't involve special IC's....something that is
probably buried in simple electronics theory, but outside of the beginners
texts that I've read so far. Earlier threads about chains of
inverting/non-inverting integrators come to mind, but I really couldn't
follow it enough to know what to do with all those taps...tie 'em together?
Nah, it can't be that simple.

-Darren