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I have not needed to replace output tubes on my 340a or 399...when it comes time, is the 340 auto bias? Does one need to buy a matched pair or quad for it? I see a "dc balance" control though.
The 399 looks like there is a bias adjustment. Any advice on what/how one needs to do when replacing output tubes on either receiver would be appreciated?
read the link it answers most of your questions.
Thank you for the link.
So no adjustment for the 340a and matched pairs of outputs or, even better, a matched quad of output tubes would be the way to go.
More to read
What about the DC balance pot?
I'm talking with very little knowledge here. However I always feel it just makes life easier buying output tubes in quad sets. Kind of eliminates the mystery of what tube has/had those numbers on the box.
And I do believe there are bias pots for those stereos.
However you will have to read the manual
Thanks for the link.
Agree with you and buy quads whenever I can...even for my 8b which as an 'easy' bias adjustment for each tube.
It looks tricky. You have to use the DC pots and connect to a resistor. Then calculate the ma/v you need.
It's easier than it seems but I have no idea of the formulas to calculate the volts from the ma.
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