2. amps-preamps
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What do you think of this preamp design?

I've been on the hunt for a preamp and came across the Audio-gd C3 final version:

http://www.audio-gd.com/Pro/pre/C3End/C3endEN.htm

It comes with schematic of the signal section. Does it seem to be well executed? Any obvious or subtle design flaws? It has had some positive reviews by owners on the web.
dracule1

Showing 2 responses by ngjockey

ngjockey
1,042 posts
 
Looks a bit like PS Audio's gain cells but more complex and less "empty" box.
ngjockey
1,042 posts
 
After a little bit of research, this I/V volume/gain control is based on a "Gilbert cell" and is available in CMOS in something like a AD835, although I have no idea of what is used in the Audio gd, PS Audio and Ayre VGT (KX-R) circuit. The advantage of this circuit is consistency through it's range, and allowing much higher impedance than the "standard" 10K to 250K ohms. Any claims of audible superiority I'll leave to the manufacturers and your own ears. Audio gd extends the concept with it's CAST-like I/O. Krell has a US patent but did not invent the technology. Seems like the most common use for this type of circuit is in phone systems.

We'll be seeing more of this type of control.
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