Preamp Deal of the Century

Thanks Kgturner!

I will let my officemate send his inquiries to that email address then.

regards,

Abe

To all Chardonnay owners,

Can any of you guys help me out here?

1) Why are the tubes marked left and right? And how do I buy left and right tubes? Matched tubes mean it doesn't matter whether it is fixed on the right or left, correct? So why mine came with instruction that 1 pair goes to the left/right and marked accordingly?

2) Do I have to do some sort of internal adjustment for gain/bias when I change tubes to match left and right channel?

3)Anyone out there managed to trace out the circuit? Or managed to identify all important components? I am worried that in long run I won't able to do any repairs if necessary. In my country good technicians are rare breed.

Thanks in advance.

ST

Mick marks them left and right becuase that'sd where they were when he tweaked the adjuustments. He has told me it is not important to keep them that way since the channels are very close.
The Chard is self-biasing using a cathode resistor and capacitor, so there is no need to adjust bias with different tubes.
I have been deep inside my Chenin and done a lot of mods, but I have not completely traced out the schematic (the Chenin has an added layer of complexity because it includes a phono stage). Don't know where you can get one, either.

Further Chenin Tweaking (7193/2C22)

Well, I took the next step and replaced the plate resistor of the 2C22 tube with a constant current source, using an IXYS IXCP10M45S current regulator chip. A resistor in series with the chip adjusts it to whatever current you need. I'm running at 11mA current, with 3.45V of cathode bias (4 Cree SiC Schottky diodes replacing the cathode resistor and capacitor) and ~150V on the plate. The sound is incredible - this is the best my system has ever sounded!

A CCS gives you a horizontal load line, meaning very little distortion and maximum gain. It is unbelievable how real the music sounds now, even with the simplest possible CCS.

Next step is to try a more complex CCS using cascoded IXYS chips - the word is that the more complex CCS sounds even better, but that's hard for me to imagine.

Just thought I'd give a heads up to anyone who has done or plans to do the 7193 mod. Adding the diode bypass and CCS is easier than doing the adapters, and the payback is HUGE.

Correction, the last paragraph above should read "diode bias" not "diode bypass".