Tube Problem

For those building and repairing amps on their own. Learna and share ideas.

Tube Problem

Postby inisio on Mon Mar 06, 2017 10:34 am

In one of my dr103 clones i have a very peculiar problem. lets say i've biased my tubes to about 35ma across every tube evenly. and then after a couple of hours of playing, V1 29ma, V2 35ma, V3 39ma, V4 35ma. I cant seem to find what's causing this. and after this happens the tubes are not "matched" any more, since the decrease/increase is for that tube specifically.
so how can something like this happen?
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Re: Tube Problem

Postby Unit_1 on Mon Mar 06, 2017 7:26 pm

Tubes can drift during break in, which is why you're supposed to check them after they've been used for several hours. If you rotate the tubes and there is no further change, then you'll know it was breaking in that did it.

If you switch the 39 with the 29 and the 39 changes to 29 then you'll know there's something really weird going on.....

Just wondering what brand tubes are they?
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