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I’ve been through this too many times. Hum, hum, hum.... A ground issue somewhere is not super useful. I followed the ground from one end to the other. Nothing is connected to ground that shouldn’t be or visa versa. Not that I can find, I should say that. So....this leaves me...where? Sadly, at this point, I just want the amp. Project time seems to have outlived it’s usefulness. Hope someone has a clue. If someone had an issue like this or has some knowledge it would be a big help. I do have a speaker cabinet anyway.

Sorry to hear about your hum issue. Yes, hum is frequently caused by a bad ground somewhere. Other things can cause it, though. Bad tubes, bad filter capacitors, bad patch cords, bad layout. etc.

More information would be helpful. Does the hum get worse if you increase the volume? Do you still hear it with the volume controls all the way down? Do you hear it with nothing plugged into the input jacks? Does it matter where the amp is physically located? Is the amp connected to a good grounded power outlet?

Some pictures of the chassis wiring and voltage measurements would be helpful. too.

Thx for reaching out. Obviously my patience is running low. Lol Yes it hums and hums. No matter what. Nothing plugged in. Just speaker. Volume control doesn’t affect it. Followed everything for one end to the other with a meter and a flashlight with nothing seeming out of place. I WANT to just throw it all in a box and forget it but I want to play it! Lol So onward I trudge.

Dave, please post some pictures. Hard to diagnose without them. Also, you may have already checked, but I once melted the inner insulation on the signal wire to the shield (believe it was on the input) and since then I check shielded cables for continuity between shield and signal wire. Also, I clip a heatsink to the signal wire and shield when I solder them in. Anyway, good luck and keep plugging away.

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"The only problem with being retired is you never get a day off"

Thx, I decided to make a clean break. Pulled the board and input jacks and checked the connections above and below. In case any resistors got cooked I have some more coming today. Could still be 120 cycle hum. My money is on that at the moment. Hope not. Haven’t got any more electrolytics here at the moment. Lol Either way, I’d like to think I am getting there. Real life lesson. You order something and first thing they say is “Check and make sure you have the right components in the box and that they actually do what they say they will”. I guess there is a lesson in there somewhere...maybe not “Don’t trust me to send you proper stuff” but maybe “stuff may not be what it says should you be building in general, so check them before building”. We’ll keep a good thought...