Amplifier Hum


I have an Aragon 4004 MKII which is emitting a humming noise from the amp itself. The noise is there regardless of volume, and it is not transmitted through the speakers. Someone told me that it may be transformer that needs to be replaced.

Does anyone here know if this is the problem? If it is, what does that entail -- i.e. shipping it to Aragon? Can this be fixed locally, or by myself? Should I not even worry about this problem?
1musiclover
For a transformer to hum, the gapping in a standard (i.e. square) transformer is off by some very small amount, whether in the gap itself or in the lamination spacing. When the gapping is off, the transformer suffers from eddy current losses that emit audible harmonics (i.e. a hum). In other words, the transformer is either loose as mentioned above, or the lamination has separated (both often the same problem). It is possible that there is a frequency problem that can induce such noise but if so, the problem lies in the rectifier and not the transformer. If a toroidal transformer makes noise, the design is most likely bad (that means get a better amp). I would check the transformer to make sure its mount is tight since the hum is actually a vibration that can make the problem worse with time by loosening it. If you put your hand firmly on the transformer, the problem should disappear in this case. Otherwise, take it to a pro for a close look at the rectifier circuit. Good luck! Arthur
I had the Big Rotel and the amplifier hum drove me crazy. The solution was the AH Offsett Killer. You can read reviews on it on Audio Review under the "others" section. I have since upgraded to a Clase thats dead quiet so I do not use it anymore. I would be willng to lend it to you to see if does the trick.
Yes, the rectifier problem I alluded to is generally a DC offset voltage that can cause a hum as Darryl found out. You might want to take his advice and see.
Thanks for your responses. You have all provided advice to consider.

Matty -- perhaps you need an exorcist.

Gooddomino -- have you ever tried correcting the problem? Do you know if the transformer is a torroidal design?

Aball -- someone else said something about the laminations coming apart. I assume it is safe to touch the transformer while turned on?

Darryl -- what is an AH Offset? I be interested in researching it!