• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

diy tube amp problem

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I changed 300b tubes with new ones after the tube amp was unplugged from the wall for a while, and smoke started coming out from the tubes,then I turned it off and unplugged it, I made sure all the tubes were plugged in the socket before turning it on. Then I tried it again and hear a very strange noise coming from the amp. So I took them out and then I noticed brown burn marks at the top of the tubes. I put the original ones back in and they didn't burn but I heard the strange noise coming from the tube amp so I shut it off immediately. What should I do? Is this could be caused by a bad tube socket, or just a bad solder point.. anything else that could cause this problem?

thanks
 
Judged by ectobia´s description I think that the tubes were possibly bad, plugged the wrong way around or whatever. This caused a short somewhere in the circuit - which still exists - and now the high current in the mains transformer "resonates" its windings, thus the "strange sound from the amp".
 
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