• 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.

Problem with old tube amp

If Tim says class A, he ought to know😉 I would say the 859 was nominally 13 watt, and later (869) 15 watts, Half 32 watts is 16 so I suspect it is. Also I would imagine if the amp was run significantly into class B it would mess up the DC feedback and introduce strange artefacts with the 2 feedback loops. I haven't studied the circuit enough to state that with certainty but it would seem likely.
 
  • Like
Reactions: Rait
If Tim says class A, he ought to know😉 I would say the 859 was nominally 13 watt, and later (869) 15 watts, Half 32 watts is 16 so I suspect it is. Also I would imagine if the amp was run significantly into class B it would mess up the DC feedback and introduce strange artefacts with the 2 feedback loops. I haven't studied the circuit enough to state that with certainty but it would seem likely.

Thanks for you time. Fun is the amplifier top plate. Surely they late understand that this statement is too much. Seen photos from some years late made 861 and there aren't this statement any more. Here photo.
 

Attachments

  • 814CED40-C207-46AA-A78A-5314402E5D41.jpeg
    814CED40-C207-46AA-A78A-5314402E5D41.jpeg
    426.9 KB · Views: 77
My German is more than a half Century unused, so I've forgotten German contractions. All I really remember now are lyrics to Die Fledermaus and Die Lustige Witwe, but can still sing the 4th movement of the Ninth. Strangely, nobody enjoys my version. Oh, well.

All good fortune,
Chris
 
Had hope to receive today resistors shipment and planned to have exciting weekend with repair but see now that package delivery is on Monday 🙁.
Longer waiting make it sweeter - Hope there is such expression in English also.
 
Hi!
Problem solved😊. Had time today to change all ordered resistors. Now both channels identical. Attached new scope photo.
All thanks to Diyaudio members, specially to Chris who studied diagram and pointed correct point to check out.🙏

Rait
 

Attachments

  • 67B02549-16B1-475C-8A6C-CA6DD1454E52.jpeg
    67B02549-16B1-475C-8A6C-CA6DD1454E52.jpeg
    419.9 KB · Views: 53