strange idea....

[Harry Bissell]

The "two delay lines" should be easy this day and age. I'll be trying this with my
cheapo Digitech S-100 (its sounds good but it was only $150... thats cheapo
compared to what I paid for Yamaha... DeltaLab... etc). Thanks for the Idea !!!
:^) Harry

mbartkow at ET.PUT.Poznan.PL wrote:

> > Anyway, you see this "beating" effect of the 2 grids cancelling
> > and reinforcing difference patterns (if i remember my yr 11
> > physics, Newton's rings?!).
> >
> > Well, I figured I was looking at a really complex filter. The closest filter
> > i could think of that might have a similar characteristic (if u could even
> > compare light and audio filters!)
> > to a comb filter. Depending on the angle you look at the screen, and how
> > close you are, all manor of crazy patterns are created before your
> > eyes!
>
> Well, this whole Moire stuff is a very clever way to obtain
> a variety of complex patterns (be it harmonic pattern like in FM synthesis,
> or formant pattern like in subtractive synthesis) using very few parameters.
>
> What is attractive to our ears is if these patterns change over time in
> some (rather ordered than random) way. That was Chowning's major achievement-
> he gave us a way to produce complex evolving spectra controlled by one or
> few parameters, which in turn was easily controlled by envelope generators.
> I think Bud's inspired idea may be realised in a simple way. Take two comb
> filters and set them in series. Now, if the base frequency (the distance
> between consecutive peaks in the frequency domain) in one filter is different
> to the other one, interesting "beating" between the bands occur.
> In case the comb filters are realised with BBDs one has to take care to
> precisely damp the clock bleedthrough as well as the spurious output spectra
> components, especially at the output of the first filter in series. Otherwise,
> nasty intermodulation of clock signals will destroy the subleties of filtering.
> Of course, slightly changing the clock rates would most probably drastically
> influence the beating pattern between the comb bands. Expect nice effects,
> similar to those known from KORG/JH triple resonator.
>
> regards,
>
> MB