[sdiy] Patchell's Boggling 13700 Expo Converter Thing???

[Jay Schwichtenberg]

I've wondered about the S/N of the circuit with 2 realitively noisy OTAs
(compared to a good or high end op-amp) in the audio path. To me it seemed
like the issue of the advantages and why of the circuit have been skipped.
Could just an op-amp V to I converter accomplish the same thing?

Jay



> -----Original Message-----
> From: owner-synth-diy at dropmix.xs4all.nl
> [mailto:owner-synth-diy at dropmix.xs4all.nl]On Behalf Of Oakley Sound
> Sent: Monday, June 23, 2003 1:39 AM
> To: synth-diy
> Subject: Re: [sdiy] Patchell's Boggling 13700 Expo Converter Thing???
>
>
> > I found another reference...It looks like Tony has been using the
> > circuit as well...
> > http://www.oakleysound.co.uk/vca-doc.pdf
>
> Yes, I took my idea from the EDN circuit. I changed it a little bit, but
> its more or less the same. I don't think its quite as good as Mike Sim's
> suggests in the article, but I can't measure THD/noise that accurately
> in my little workshop. So it may well be. Simple tests make it a
> maginally better circuit than either CA3280 or BA6110 operated singly.
> [better S/N, better CV rejection]
>
> Regards,
>
> Tony Allgood                       Penrith, Cumbria, England
>
> Oakley Sound Systems                   www.oakleysound.co.uk
>
>