• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Quad II - Forty

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Dear Mr. Alessandro,
I haven't Quad II - Forty scheme. This scheme is the same Quad II mono amplifier (KT66) 1949-1970. I have followed and checked the voltages in this scheme and montage. I have to tell you that Quad II - Forty has higher anode voltage than Quad II mono amp anode voltage.

Regards, Georgi Georgiev, Bulgaria
 
rossdt said:
Thank you very much!
What is the black component under the rectifier?
Thanks

Alessandro

It is a very low value thermister in series with the rectifier (5U4) filament to give a kind of slow power-up.

The Quad II-40 circuit is essentially the same as the Quad II, with some slightly different value resistors to accomodate the 6SH7 drivers. The other difference is the separate cathode resistors (bypassed) for the KT88 power tubes.

Regards
 
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