If cleaning the hum pots doesn’t work you might want to try these. Are you thinking about selling it? Or trade?
Dennis
The only way to reduce the hum entirely is to go with DC filaments.Sadly, I've shelved this amp and have gone back the Redboy 45.
As @paulbottlehead noted, it does have quite a bit of 60hz hum. Lived with a quite a while, going back really made me realize how bad it was. Not sure what I'm going to do with it at this point.
Wondering if there might be an easy fix, or what steps to take to try and reduce or eliminate it. First step when I get a chance I'm going to clean the hum pots. They were pretty scratchy and did reduce the hum, but not enough.
Was also going to suggest just rotating the output transformers 90 degrees and see if that helps.The only way to reduce the hum entirely is to go with DC filaments.
If it is being induced by the power transformer, you could rotate the output transformers 90 degrees.
The system I had at the time had 2 Altec 288 CD which are 115db efficient so almost every amp had a bit of hum. However unless the hum is very sever the hum disappears when the music starts.Would be nice if it's just the hum pots and/or a DC supply were to fix the problem. However the Redboy 45 here is really close if not the exact circuit and I'm perfectly happy with it's level of hum. I'm afraid it's more of the transformer alignment like @paulbottlehead noted. Do you recall it having a hum when you had it?
Was also going to suggest just rotating the output transformers 90 degrees and see if that helps.
Should be a quick and easy fix.
You could turn the one (only) closest to the power transformer as a test.Unfortunately, the transformers are not square and eyeballing it, there does not appear be enough room on the chassis to turn them 90 degrees.
Thought about a piece of metal as a shield to test. Don't have any MU here. May have to order some. Thought about maybe a cover for the power transformer to shield it. I've also thought about making a new larger plate and chassis and moving all the components over. Also thought about using different output transformers. Free time to do all this is constantly a problem.
Thought about a piece of metal as a shield to test. Don't have any MU here. May have to order some. Thought about maybe a cover for the power transformer to shield it. I've also thought about making a new larger plate and chassis and moving all the components over. Also thought about using different output transformers. Free time to do all this is constantly a problem.
I wish I could help further but I'm really bad at remote sleuthing.
You were not in politics in a different life were you? Great response and tactful, and I agree.The coil axis of the power transformer is perfectly aligned with the coils of the output transformers; this build is a bit scratched from the start.