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Amp hums when on same circuit as line conditioner

I have a Classe ca-200 which has never hummed before, but I just put a furman voltage regulator/line conditioner in my system, and if the amp is connected into the line conditioner or other socket that the line conditioner is plugged into, the amp hums (the transformer i'm assuming). If the amp is plugged into a different socket(on the other side of the room) and everything else is the same, it does not hum. I've tried all sorts of combinations, and the only way to get rid of the hum is to turn off the line conditioner or to plug the amp in a socket elsewhere. Any clues as to why this is happening?

Jon
crzyjt
9 responses Add your response
bob_bundus
1,834 posts
 
whatever you do, do not install any type of GFI protector. These are the 2nd worst noise producers around, aside from many cheap light dimmers.
Having no connection to earth ground is a likely cause of the symptoms however.
wnegele
2 posts
 
I agree with joebrams. I had the same problem with my Audio research amp. Remove it from the power conditioner.
elevick
2,636 posts
 
Some conditioners can't work properly unless on a grounded 3 prong outlet. I know that I had a monster conditioner that stayed in protection mode but my adcom works fine. Contact furman. You may have to get a different conditioner. By the way, for safety purposes you can remove the old outlet and put in a GFI without a ground. This will eliminate the use of a cheap adaptor and can save things in case of a major fault.
turbofun
6 posts
 
Try reversing the polarity on your amp. You may also have
a grounding loop.
joeabrams
132 posts
 
It means that when your amp is on that conditioner, it is being starved for juice. Period.
crzyjt OP
1 posts
 
Well, if you mean an adapter to convert the three prong grounded plug to a 2prong plug, I already have one in use because none of the sockets in this old house have the 3prong grounded outlets. There's no dimmer switch, and I don't know how to check the phase/leg. But, the amp never did this before I put the a/c conditioner in the circuit, and if i take it out, the amp does not hum. I was just wondering why an a/c conditioner might affect the amp, since it doesn't seem to affect any of the other components.
scdrj
6 posts
 
Stehno has a good idea. You may also try using a plug fouler.....ground cheater......a adapter that eliminates the ground connection on the amps power plug. If this solves the problem, you have a ground loop problem.
chichiuno
118 posts
 
Do you have a dimmer switch on the same curcuit?
stehno
1,453 posts
 
Check to ensure that the circuit the outlet in question is on the same phase/leg back at the service panel.

If it's not, hire an electrician to carefully move the circuits around so that all of your audio outlets/lines/circuits are on the same phase/leg in the service panel.

I had a small transformer hum in my amp and doing the above resolved that issue.

Of course, that does not mean it works every time. But it never hurts to arrange your audio circuits this way anyway.

-IMO
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