ID'ing F30 Tubes

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fsmith

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Looking at the back of my combo how are the 12AX7's numbered? I see 3 that have the tube covers and one that doesn't. Should all 4 have covers?

thanks,
fred
 
Yes they should. It doesn't impair the amp's performance but it keeps the tubes from dislodging due to vibrations, and I think it protects also against microphonics (also due to vibrations) but that I'm not sure.
 
fabien said:
Yes they should. It doesn't impair the amp's performance but it keeps the tubes from dislodging due to vibrations, and I think it protects also against microphonics (also due to vibrations) but that I'm not sure.

Sounds right to me.

The preamp tubes are numbered starting closest to the input on the front of the amp. So the tube nearest the input is V1, then V2, and so on...
 
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