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Old 04-21-2008   #34
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Join Date: Aug 2007
Location: TX
Posts: 506
Default Re: Which power supply???

Originally Posted by HT Junky View Post
Hey Ken,

Have you noticed that your amps have a little bit of transformer hum when using the PurePower? Both my Musical Design amp and my Outlaw Audio 755 amp have a little bit of transformer hum. It is loud enough that you would notice it when the system is idle, if the amps were out in the open.

I have the amps in the back of my rack, so it is of no concern to me. They even have this transformer hum when plugged into the same circuit as the 1050, but not into the 1050 itself.

I talked to Musical Design and Outlaw Audio. Both mentioned that there must be a little DC leakage into the line somewhere. It makes sense, given the battery is an integral part of the design of these units. Both manufacturers also said that it, in no way, should be a concern to the amps proper functioning.

I plugged my whole system into outlets on the same circuit, but not into the 1050 (so nothing was plugged into the 1050). If I plug the 1050 into the same circuit, my amps have transformer hum. When I unplug the 1050, it stops. The transormer hum was also there on the first unit (1050) that went bad on me.

Like I said, it is of no concern to me, but if my amps sat out in the room it would annoy me for sure.
I really dislike hearing hum, and would probably pull out anything making it. My experience has been that hum is usually due to a grounding problem. Maybe something in the 1050 is loose which could eventually cause it to fail, like your first unit. As much as you paid for a 1050, I would think hearing hum would be unacceptable. If there is "DC leakage" I would ask for a unit with a better quality build that is not "leaking."
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