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  3. 1075927385

New hum in preamp power supple and BPT 3.5 ???

Hello. A few days ago, I noticed that my First Sound preamp's power supply was humming loud enough to hear about 4 feet away. Then, my formerly dead quiet BPT 3.5 started humming, too. The BPT hums with or without anything plugged into it. Could I have a ground problem? If so, how would I find it and fix it? I have a metal strap attached to my cold water pipe. Also, a friend of mine said that all the houses in my neighborhood use the conduit/outlet boxes as the ground. He mentioned this to me when I asked him about installing an ACME outlet. There was no copper wire in the box to attach to the ground screw on the outlet. He said just the screws attaching it to the outlet provided the ground. Thanks for any ideas you may have.
brooksl
sugarbrie
3,854 posts
 
Oh..rats... My last comment then means it might be hard to fix. The same thing that the conditioner fixes (ie, the gear transformers won't hum); unfortunitely the conditioner's transformers are getting the same "off" power from your neighborhood power grid.

Did any of the gear transformers hum before getting the BPT 3.5? Let's hope it is a temporary problem (like your utility doing maintenance) and it will go away.

You could get a dedicated line if you don't have it already. Can't hurt. Very last resort is put the BPT in another room and use a very high end power strip with a long extension power cord?

Or try another brand balanced power device....
rsbeck
887 posts
 
I had a similar problem. In fact, my amplifiers (Levinson 436's), sub-woofer, and BP-3.5 were all humming. So, I installed dedicated properly grounded 20 amp circuits with Hospital Grade Outlets. Problem solved.
I think the BP-3.5 likes to be fed 20 amps. So did the amps and Sub.
Now, everything is stone silent and sounding great, night or day.
brooksl OP
129 posts
 
The circuit I am using now is 15 amps. I have been meaning to install dedicated lines. This problem inspires me to do them now. Thanks for your help, guys.
sugarbrie
3,854 posts
 
Brooks1 could very well be right on the money. The tranformer hum is a problem with the electrical current, so give the new 20amp lines a try. Good thing to have anyway...
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