[sdiy] Using analog for physical modeling

[Harry Bissell]

Through zero flanging can also be done using a cascaded all-pass filter as a
(reasonably) flat delay. one half of a dome filter (see Haible et al :^) can be used.

Digital delays tend not to have a very wide range of clock frequency, so the through
zero flanging might be (can I say this outloud?) inferior to a BBD approach.

Delta modulated delays (Delta-Lab) seem to fare better for wide clocking frequency sweep.

now... if you just take a couple of tape recorders :^)

H^) harry


----- Original Message -----
From: Brock Russell <brockr0 at shaw.ca>
To: synthdiy diy <synth-diy at dropmix.xs4all.nl>
Sent: Wed, 21 Sep 2011 12:47:06 -0400 (EDT)
Subject: Re: [sdiy] Using analog for physical modeling

At 02:14 AM 21/09/2011, Tom Wiltshire wrote:
>Isn't that what the Princeton PT2399 is trying to be? - except that 
>it won't go short enough to do flanging, and only just for chorus. 
>PIty, that. So close, but no banana. They should have added a VCO 
>modulation input too, to save the craziness people do to modulate 
>it. Still, it's about the best modern option, and very much the 
>successor to the original BBDs.
If you want the PT2399 to do flanging, run two in parallel. 
Modulation requires changing the frequency set current sink resistor 
with a variable current sink which requires the addition of a 
transistor in the most primitive implementation. The real pity of the 
PT2399 is that they did not provide for external clocking which would 
enable much easier cascading and syncing of multiple devices. I agree 
that it is the best modern option to BBDs when you consider bang for 
the buck and ease of implementation.

Brock 

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-- 
Harry Bissell & Nora Abdullah 4eva