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How to get rid of transformer hum?

I have a pair of Pass X600s and an ac line with about 5% clipping of the sine wave. This gives me a large amount of transformer rattle (mechanical hum). I have built a line filter with two diodes and a couple of caps that has gotten rid of 80% of the noise but I'm looking for a inexpensive fix. My power company will not fix the power coming in unless it is clipping by more than 7%. Any suggestions?

Tommy
tommy

Showing 5 responses by tommy

tommy OP
32 posts
 
Both amps hums just alike. Before building a filter made up of two caps and a diode I could hear the hum when I walked into the room. Now I hear it when I walk over to the amps. I'm just looking for a fix that doesn't cost 5 grand. Any thoughts?
tommy OP
32 posts
 
Guys thanks for the feedback, I do have two diodes invertered, and prior to these amps I had Cary SLAM 100s which didn't rattle at all. I did speak with Nelson Pass and he is the one that gave me the filter idea. I can't tighten the transformers anymore so I'm looking for a way to clean up the sine wave. I may have to resort to a conditioner by PS Audio or Exact Power. Any other ideas.
tommy OP
32 posts
 
Steve

I have decaded 20A lines to each amp and voltage reads a solid 119 plus change on each one. Do you think any of the power conditioners will fix this problem? Do I put the second set of diodes across the first set? Thanks Tommy
tommy OP
32 posts
 
Steve

The mfg said that is the power that is causing the hum and sure enough when I made the filter it got rid of about 80% of the hum. I posted this thinking that someone else might have a easy cure. I'll clip some more diodes across to see what happens since they cost about 60 cents a piece. Thanks again for your input.
tommy OP
32 posts
 
Mrderrick

The amps were at another home with the same power company. They didn't hum there. I listened to the my parasound amps in my surround system and they hum too, they are behind a wall and the transformers are about 10% of the size of the Pass. I've had the power company out and I saw the sine wave on there scope it was chopped off at the top. Just not enough for them to work on fixing it.
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