AW: [sdiy] PT2399 site with sound files

Nils Pipenbrinck np at
Mon Aug 26 12:17:49 CEST 2002

Scott Stites wrote:
> I'd say the one drawback of the PT2399 is the
> minimum delay time - a little too long for true flanging.  That being
> I've goosed the minimum delay time to around 17 mS (if my scope ain't
> lying - this is contrary to the data sheet), which puts it into the range
> for chorus type effects.  Also, I do get some comb effects that could only
> be described as "granular".

That just remindes me of a very cool feature of my digital guitar chorus

It has a predelay feature. Combing is done with two (or more.. who really
knows) modulated delay lines. Both the feedback as well as the source signal
must pass the predelay each time. This gives a very rich and deep
chorus/flange where you can set the modulation and feedback to extreme
values without getting this ugly and cheap sounding (my oppinion) up'n'down
going effect you can hear from cheap chorus units.

The more predelay you use the broader the sound gets. Only drawback is, that
you get some slapback style delay on your signal as well.

I think you can have the same effect by using two delay chips. You won't get
your BBD style flaging, but it gives extreme flanging sound in a complete
different manner.

	Nils "who overused chorus effects" Pipenbrinck

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