[sdiy] BBD Chips

[Scott Stites]

But wait - don't ensemble choruses by nature have the BBD clocks 'crossing'
themselves in the frequency domain?  Now I'm confused.....


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Subject: Re: Re: [sdiy] BBD Chips
From: Roman <modular at go2.pl>
Date: Tue, 22 Jul 2003 17:03:06 +0100
To: synth-diy at dropmix.xs4all.nl

I know at least one person who'd hate me for saying this, but...
What if we use 2 BBDs and 2 clocks. When one frequency rises, second drops. When
frequencies are equal, there's no delay between BBD outputs, so flanging can
begin at zero delay, or go back and forth into positive and negative delay. As
long as there's no original signal added, and everything passes thru BBDs,
there's no minimum time limit.
Only twice the noise...

Roman

---- WiadomoϾ Oryginalna ----
Od: Scott Stites <scottnoanh at peoplepc.com>
Do: synth-diy at dropmix.xs4all.nl
Data: Tue, 22 Jul 2003 06:39:20 -0700 (PDT)
Temat: Re: [sdiy] BBD Chips

>I've gotten very good results both for chorus and flanging using the MN3207.  The
<br />
>spec sheet gives a 200 kHz max clock rate for a minimum delay time of 2.56 ms,
<br />
>which is in the heart of flanging territory.  Seems I've overclocked the chip too
<br />
>for even better results with no problem, but I'm at work now and can't remember
<br />
>the particulars.  Looking at various manufacturer schematics for flangers,
<br />
>choruses and ensemble choruses, it seems they routinely overclocked BBD's.  Maybe
<br />
>Harry mesmerised the manufacturers and overclocking *really* destroys them =0). 
<br />
>
<br />
>The MN3102 clock is definitely worth the few extra bucks.  It rather
<br />
>uncomplicates things, and the waveshaping in it helps to ensure you don't have
<br />
>any clock overlap.  Using that, the addition of a couple of transistors makes a
<br />
>nice logrithmic current sink for flanging.
<br />
>
<br />
>Cheers,
<br />
>Scott
<br />
>
<br />
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>

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