Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: dwp on June 20, 2010, 11:03:29 pm
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OK so I know this is totally subjective, but per continution of my last thread, AB763 re-build to 5F6A, I've noticed the PT is producing heat. not to the point of unable to touch, but moving past warm, to hot say? Since I don't have a lot of comparison background, am wondering, should I be worried? Is new MM iron, well several years old, but never been played out, weekend warrior in the house only.
Since I'm fixing to give this build away to someone who will be jamming with band regularly, I've been road-testing, playing on 8, (8 on the skirted knobs) I notice that it is hot towards the end of an hour. Doesn't get hot faster than that.
Also, I installed the bias pots pointing out the back where the ground switch would be. (BF super Reverb chassis) that's right behind the output tubes, and the chassis is hot also at that location. Think this is bad thing since they're controlling output? hot, then not, then hot? over and again......
6L6's, 35MV/460VDC, MM Blackface iron, 5F6A circuit for the most part. Assurance or concern?
Thanks again, dwp
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Many tube amps ran too hot to hold all over.
A 50W amp's PT hot in an hour is normal. If you can hold it for 10 seconds at the end of the night, it is cooler than many.
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Also, a hot PT could be hot just because of nearby power and rectifier tubes. The PT area of the '67 Super Reverb I used to own was hot due to the GZ34 and 6L6's, especially if I had just finished playing a set.
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Hey thanks for the answers. I have always checked for stuff like that, but playing at bedroom level does not cause the cores to heat up at all. It was alittle alarming because that and the output tubes is causing the chassis to get really hot, am now going to rethink bias pot locations, anything else making direct contact with the chassis on the south end.....
Thanks again, dwp