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Ground Loop Problem - Stumped

I've got a nasty ground loop problem that I can't seem to figure out. I've done extensive research and tried just about everything but to no avail. Here is how I have everything connected. I am using the ExactPower EP15A and SP15A. All of my sources both digital and analog are plugged into the SP15A which in turn is plugged into the EP15A. My amplifier is plugged into the EP15A. The EP15A is plugged into my wall outlet.

1. I removed all the interconnects between all the components but kept the speakers connected - NO HUM.

2. Connected my preamp (Meridian G68) to my amp (EAD PowerMaster 8300) via RCA interconnects - HUM.

3. The hum is not affected by volume level.

Any ideas?

Thanks
nvlashi
jea48
4,495 posts
 
">>All of my sources both digital and analog are plugged into the SP15A which in turn is plugged into the EP15A. My amplifier is plugged into the EP15A. The EP15A is plugged into my wall outlet."<<
>>>>>>>
The SP15 is a balanced power output isol xfmr unit, 60/120V.
The EP15 output, I believe, is 0/120V output unit. Is that correct? Imo there is your ground loop problem. Preamp fed from balanced power, 60/120V, and power Amp 0/120V.
Just a thought.....

http://www.exactpower.com/ep15a.html
http://www.exactpower.com/sp15a.html
Jim
czbbcl's avatar
czbbcl
1,752 posts
 
Is this a recent occurance? Did you change something or add acomponent or has it been there for awhile? I would start by lifting the grounds on the components to determine which component or components is causing the ground loop.

Chuck
etbaby
138 posts
 
The EP15 is floating the ground from your electrical outlet. This is causing the hum. Call exact power and see if they have a mod for this problem or if they give you some procedure for grounding the unit.
hifi57audio
15 posts
 
I Haven't the time right now to read all the responses, so forgive me if this has already been addressed. The hum you describe is likely 120hz(full wave rectified 60hz line freq) picked up from the power supply. The difference in voltage drops between your two grounds,the innterconnects, and the power cords,cause this noise. If only one power ground,generally at the preamp, is used ground loops can be avoided. HOWEVER, if the interconnects come off you gots an ungrounded piece of equipment. Not good.
dacostab
84 posts
 
Are you sure your interconnects are good? You may want to get a meter and check continuity.
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