Richard and Jim, ?

I got caught on the top paragraphs, and did not go thru it all.. but…!!!

As I have seen it, at 10mfd, C44 is hopefully ?holding the ?“reduced B+” steady for both parts of the 6SC7, including the voltage to all the “stuff” going to the Right plate. If we don’t have a consensus there, It is hard discuss any of the filtering business. If that C44 ?point is not a fixed DC voltage, the left tube will go wonky too. ?

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As Jacques mentioned, the switch “IN” position does boost the base at the expense of all else; Early on, I did not think about C42 associated with the tone control [ya, I assumed..], but it becomes obvious that this cap likes to gobble up the mids and highs, leaving a dominant base response.

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The OP [Jim] said originally ?“Radio is working well except for a 120hz hum. ??When I switch the Bass in, the hum goes away.” So to me hum is there in the “OUT” position and so the hum would seem to be related to the choke area stuff and its wiring. ?There is no obvious ground to open in the area, but Nearby B+ will easily couple to any open connections. ??Here would be my FIRST look, with switch wiring first.

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Presumably there is a normal radio signal with hum on top of it ?? and not just hum??

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