Possible Over Heating
Question:
When I was playing with the Bassman Reissue LTD, for about two and a half hours. At the end of the session I notice the chrome top plate (volume & inputs) and the top 3 screws were so hot I could only touch them for no more then about 3 or 4 seconds, is this normal for the top plate & screws to be this hot.
Its just had the lower-gain tubes inserted this week (12AU7 12AX7 12AY7) in replace of the 3 higher-gain tubes (12AX7).
The amp has come from Hong Kong and set up for 230volts, and change only this week to 240volts for Australia.
It sounded great at the session, so I hope all is ok.
Reporting back, the amp was properly biased and no trouble so far. The B+ voltage was some where between 480-500, would need to retest it to find out exactly. Would like to know more on B+ voltage & biased, thanks.
Hello Troy- A real discussion of B+ voltage and bias would take a lot of time and put most people to sleep. Just be confident that Fender knew what they were doing when they designed your amp. I would want to see the bias in the range of 25-35 milliamps, and I suggest Sovtek 5881WXT power tubes as a reliable choice for your amp.
Skip Simmons
Hello Troy- Thanks for writing..... good question! One of the quirks of all Fender amps is that the tubes are mounted directly below the chassis, and after several hours will get the chassis pretty dang hot! Despite this, don't forget that Fender amps have set the standard for reliability since their inception.
Regarding your amp specifically, preamp tube swapping will not have any effect on heat, but I would be happier telling you that "everything is all right" if I knew two things: what the B+ voltage is, and that the power tubes are properly biased. Ask the tech who changed the transformer over to 220 volt and report back!
Skip Simmons