Question for tube aficionados

Hi Folks...

Need to correct almarg and raindance about those grid resistors.  I was in touch with Jeff Fischel, now heading up c-j, about those PV-11 grid resistors.  Apparently the sources the previous posters used were wrong. Here is his reply to me:

"Bob,

 Actually on all 3 of these models we do employ grid resistors on all gain stages , typically a 47R5 resistor. All CJ preamps use grid resistors either 47R5 , 100R or 332R.

 Thanks,

 Jeff Fischel

conrad-johnson design inc.

703-698-8581

http://www.conradjohnson.com/"

Guess doing it correctly is one reason their equipment consistently sounds so good.

Actually on all 3 of these models we do employ grid resistors on all gain stages , typically a 47R5 resistor. All CJ preamps use grid resistors either 47R5 , 100R or 332R.

Thanks, Coppy. Good to know.

That information doesn’t appear to be consistent with the schematics I looked at for the PV-10 and PV-12 at HiFiEngine.com, and 47R5 (i.e. 47.5 ohms) seems much lower than usual for the value of a grid stopper resistor that would be effective in these kinds of designs. But in addition to the high confidence I would have in an answer provided by Mr. Fischel the bottom line would seem to be, as you said, that "their equipment consistently sounds so good."

Thanks again. Regards,
-- Al

I have no idea what you’re talking about, but I can tell you the preamp is terrific,
even after all these years!

Concerning the CJ PV11 amplifier, does anyone know if the two 12 AU7 tubes that drive the line stage have any effect on the phono stage at all, or do they just affect the line stage alone?

I have a Unison hybrid integrated which uses 2 12au7s in preamp end.  I have used two different Mullard 12au7s, RCA Cleartops, and Radiotechnique, but the Siemens 12au7 NOS (got mine from Upscale) beat them all.  Beautiful full bottom end, great midrange, and an open and fantastic top end, no brightness but crystal clear.  Wonderfully dynamic.