Lazarus1140
New member
No doubt there are many possible culprits, but in your opinion, what is the source of the hum.
My amp hums. Naturally, the most obvious reason is that it doesn't know the lyrics, but it hums.
Whether something is plugged into the input or not it hums. It is a low mid frequency hum. The amp has to warm up. In fact the hum increases in volume as the tubes warm up. Once it is loud enough to be heard it remains at a certain low volume and is unaffected by volume pot adjustments. I have tried it in several places in the house where there are no light and where there are no cmputers on the circuit. It is not a loud hum. It is just loud enougth to be a hassle for a soundman between songs when the amp is mic'd. The greatest problem, though, is that it hums. I don't want that and I think that it must be a sign of a bad design, a defective component or components, poor grounding, or poor lead dress. It is driving me insane because aside from the hum the amp sounds glorious.
It is basically a Blackface Princeton circuit with 3-12AX7, 1-12AT7, 2-6V6, with 5AR4. The rectifier glows a lot brighter than the 6V6s if that means anything, and I am surprised that it runs relativey hot - even at idle.
What happened to Glassman? Lew, does Bruce still check in now and then? Any help will be greatly appreciated.
My amp hums. Naturally, the most obvious reason is that it doesn't know the lyrics, but it hums.
Whether something is plugged into the input or not it hums. It is a low mid frequency hum. The amp has to warm up. In fact the hum increases in volume as the tubes warm up. Once it is loud enough to be heard it remains at a certain low volume and is unaffected by volume pot adjustments. I have tried it in several places in the house where there are no light and where there are no cmputers on the circuit. It is not a loud hum. It is just loud enougth to be a hassle for a soundman between songs when the amp is mic'd. The greatest problem, though, is that it hums. I don't want that and I think that it must be a sign of a bad design, a defective component or components, poor grounding, or poor lead dress. It is driving me insane because aside from the hum the amp sounds glorious.
It is basically a Blackface Princeton circuit with 3-12AX7, 1-12AT7, 2-6V6, with 5AR4. The rectifier glows a lot brighter than the 6V6s if that means anything, and I am surprised that it runs relativey hot - even at idle.
What happened to Glassman? Lew, does Bruce still check in now and then? Any help will be greatly appreciated.
