1957 Admiral HT2237 Capacitor

[Hi-Fi-Mogul]

Hello all,

What function does C11 (0.047mF) serve in this phono amplifier ?

It's connected from line voltage to the heater tap of the 35Z5GT
rectifier.

(across the line cap ?)

Thanks.

[electra225]

It's there to prevent hum. Notice that it is connected to one side of the filament of the 12AU6 which is the audio amplifier. This stage has the largest gain of any in the amplifier, hence its tendency to be susceptible and sensitive to hum. Connected from the positive side of the line to common negative. It's also common practice for the first audio tube, in this case the 12AU6 to be the last tube in the heater string, again to help prevent AC hum. Magnavox uses a separate tap in their power transformers to power the "little" audio tubes, the first audio tubes. This also to prevent hum and feedback.

[Hi-Fi-Mogul]

You answered my question much more simply
and clearly than all searched topics online that I
found never addressed my query. [ : )

There is a B- to chassis cap (C3 0.1 mF) that I will change out
to a 0.01 mF X1Y2 safety cap.

Is there any need to also reduce the C11 value or put an
X1Y2 cap there ?

Thanks a lot. These basic pearls are very helpful
to my rudimentary knowledge base.