• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
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    the safety precautions around high voltages.

To Schade it , or not..

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After drinking half a Ballantines bottle, I come out with this thing. Now, ten "ristretto" coffees after that, I start to suspect that there is something wrong about this plate to plate connection. Schade can wait? :confused:
 

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As long both AU6 stay in Class A, should be able to tolerate 6V6 in AB...
You got autotransformer coupling of NFB from plate of downside 6V6.
Even when topside 6v6 is temporarily class B'd out the picture.
I don't know this is Schade anymore, but still plate to plate feedback.

I'm a little more worried you got c1, c2, and maybe c5 together with
autotransformer in a feedback loop to control the downsize 6v6. One
corner has to be sufficiently lower than the rest to assure that loop
gain is down below unity before the next pole adds any more pshift.

Would R10 operate better bypassed? We want voltage linearity for
this triode strapped AU6 phase inverter, don't care current linearity.
 
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Yes probably in a nornal GNF scheme it is better to keep R9 bypassed, for a plenty of gain. (It is not pictured, but I want the amp to be an integrated, drived directly by the CDP out, if possible)
R10 unbypassed is part of the measures to have unity gain on the second AU6, a much lower voltage gain, G1 feeded trough a voltage divider, and a lower following grid resistor (R7)
Found the schematic You suggested (ARC ST-70-C3) I'll take a look on it.
 
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