Hi. I am having difficulty finding Brimar CV4035 tubes that work well with my Fisher 400 (late series), specifically the phono stage. I have purchased 4 NOS tubes, a set of two each from two different reputable tube dealers. Out of the 4 tubes only one does not produce a hum in the phone section. Two are really bad, and one is tolerable, but still has a subtle hum. I have not had this issue with any other tubes so far (different manufactures) in that section particularly. I tried moving the tubes into different sections and was able to still hear the hum in the tone control position, but not the voltage amp position, which I assume is normal for tubes with a hum. My question(s) for those familiar with the electronics of the Fisher are could this be a component issue or does the Fisher seem to have issues with certain tubes, or are these just bad tubes? Both dealers claimed they tested for hum and microphonics. I even sent one back and that person claimed they could not reproduce the hum.
Brimar CV4035 and Fisher 400
- Thread starter Tubes4Wx
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- fisher 400 hum phono tubes
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The guy who restored my 400 had done extensive tube rolling and strongly recommended Westinghoue short grey plate 12ax7s in the phono stage. Don’t know if it was the power of suggestion, but I like them over the Teles, Amperex, and RCAs that I compared them with.
I have Teles in the other 12ax7 positions.
I have Teles in the other 12ax7 positions.
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