Arp filters. Re: [sdiy] WP LM3900 VCF

[René Schmitz]

Hi Anthony and all,

anthony wrote:
> You might try all kinds of rigorous modulation possibilities. Maybe the 
> only problems that would audibly arise be control voltage feedthrough?

The VCF7 (at least the version I have on my HD) doesn't have the bias 
current correction as in the original ARP circuit, so I would expect 
some thumping when you've reached the very low frequencies. The DC bias 
of the amps will wander if the standing current gets into the order of 
the offset current of the norton (~3nA). Arp used some high value 
resistors to correct that.

That put aside a mismatch normally would generate some control voltage 
feedthrough.

Cheers,
  René

-- 
uzs159 at uni-bonn.de
http://www.uni-bonn.de/~uzs159