Nothing is failing in the chassis- both sets of tubes run off of the same bias supply. You simply have power tubes that are getting weaker.
Dynaco ST 70 bias change
I have a Will Vincent ST 70 @5 years old. I am running KT 66’s. Right channel tubes are 9 months old and left channel are about a year. Checked bias this morning (routine) and found newer tubes at 1.35 and left channel at 1.15. Last check was 3 months ago with both sides at 1.35. My understanding is that with wear/use bias will increase. I’m not a tech person (wish I was). Should I be worried about that drop? It’s always been stable for me. Sound through Cornwall’s is lovely. I guess I’m worried it might indicate something failing “inside” the chassis. I appreciate any input from the knowledgeable crowd here. Perhaps my interpretation is ass backwards too.
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