QuestionQUESTION: I have a Denon 4806 ci Receiver, when I added my ADCOM gf555 amplifier a hum started, it. The Denon is the issue as the adcom when used in the previous setup had no problem, and the hum only starts when I connect the two. I tried the RadioShack ground loopp isolator but that made the sound even louder. Any thoughts.
ANSWER: How you are connecting the receiver to the amplifier. Expain how all input and output connections. A flow diagram would be helpful.
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QUESTION: Thank you for the quick response. I am using left and right channel preouts from the denon receiver to the line level inputs on the adcom amplifier. Also it is not the Satellite as it was not connected at all during my last diagnostic. Also I have tried various power outlets including using the outlet on the receiver. I also have a seperate adcom amp running the center channel speaker and there are no issues, neither with the powered sub that is also connected through the preout.
ANSWER: Typically there is ground loop hum if you have a cable box anywhere in the chain. Make sure you test the system without connecting power or signal from a cable box to any of your equipment (even if it's not selected).
If that's not successful then I would connect a source directly to the Adcom and see if there is any hum. Also test the receiver alone, connected to speakers, to see if there is any hum. If the hum is only when you connect the Denon to the Adcom then you have an elevated ground problem generally caused by a defective capacitor in the power supply of one of the units. The simple fix is to isolate the grounds. There are numerous ways to do that. Ground lift connectors on the mains, lifting the ground at the input connection to the amplifier or many of the balancing tranformerless converters. (IE RAM Electronics)
Unbalanced circuits are a pain (consumer electronics). I try to keep as much balanced equipment in my work as humanly possible, but lo, that little help to you.
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QUESTION: yes it is only the denon to adcom connection. So therefore I have the eleveated ground you speak of. What do you mean by lifting the ground? Thanks again for your help.After much web searching ground lift is a new and seems the correct solution.
Answer1 - If any of the gear uses 3 pin AC power plugs try using an adaptor, available from you hardware store, to convert them to 2 prongs
If that doesn't help isolate the input and output connections from the Denon to the Adcom by doing the following:
2 - Removing the ground connection to the Adcom for both channels (only on the cable to the RCA plugs)
3 - If all else fails find an isolator - either transformer or Balun (http://www.ramelectronics.net/html/etslan.html)
You can speak to tech support at RAM and they may have another solution.
Worst case scenario is to find a tech to open up the amplifier and receiver and find either the cold solder joint or bad cap. I don't have much faith in the QCing of consumer gear these days.
