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Marantz Pre/Pro + McIntosh Amp = Hum

post #1 of 9
12/7/12 at 8:20pm
Thread Starter 
Just got my final (I thought) setup done and I have a pretty good hum, even at zero volume (the mute button stops it though). I have a Marantz AV7701 paired with a McIntosh MC8207 amp. I used Blue Jeans Cable XLRs for center and two rears and Audio Quest Diamondback XLRs for the two fronts. I wanted to A / B the two brands and decide if it was worth it to spend the money on all Audio Quest interconnects. Anyway, I have found that I have a pretty noticeable hum on ALL channels. Everything is powered by the same outlet and I have the Marantz Pre/Pro, TV, and all sources going through a Furman Elite 20 PFi. The MC8207 is plugged directly into the wall outlet. Any ideas on what I should do? I have read things about lifting grounds and whatnot. In my opinion, with this level of product, I should not have to do such things. Thanks for any help.

Seth
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post #2 of 9
12/7/12 at 9:54pm
did you try plugging your amp into the Furman?? you have it going to the wall direct and that can be your Hum!
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post #3 of 9
12/7/12 at 11:12pm
Thread Starter 
I have now found that the hum is also heard through headphones plugged into the AV7701, while the amp is turned off. Sounds like I have an issue with the Marantz...
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post #4 of 9
12/7/12 at 11:42pm
Interesting... I had the exact same problem with the 7701 connected to a JBL amp (heard the hum through the speakers). When my dealer contacted Marantz, they said that it worked fine with their amp and that was as much guidance as they could provide. I had an Anthem AVM50V that I tried in the same setup, and it did not have a hum problem. no idea of the direct cause, and wish that the 7701 had worked out, but ended up ditching the Marantz...
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post #5 of 9
12/8/12 at 7:22pm
Thread Starter 
Did some checking today and found that the hum goes away when I unplug the HDMI cable coming from my Directv receiver. Guess I need to check the grounding block outside where the coax comes into the house. I'm just glad that I pinpointed the source of the hum.
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post #6 of 9
12/9/12 at 6:47am
I spent hours trying to eliminate the hum in my Marantz and finally returned it. Have had 2 Onkyo prepros with no problem.
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post #7 of 9
12/9/12 at 7:40pm
Thread Starter 
Well, I have tried everything. I have grounded the dish to the grounding block outside (which grounds to the grounding rod within a few inches), ran the coax through the Furman line conditioner, and even took the HDMI straight to the TV, while using optical audio. The hum goes through the TV and then back to the pre-amp, causing hum. Basically, if I hook up the DTV receiver in any way, I get hum. Anybody got any info on this problem?
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post #8 of 9
12/11/12 at 4:19pm
Thread Starter 
Quote:
Originally Posted by promike View Post

I spent hours trying to eliminate the hum in my Marantz and finally returned it. Have had 2 Onkyo prepros with no problem.

What model AV was it and did you have sat tv going to it??
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post #9 of 9
12/14/12 at 5:31pm
Thread Starter 
Well, I finally said to hell with it and cut the shield/ground from each of the five XLR connectors at the amp's inputs. It was pretty easy, actually. It stopped the annoying buzz/hum I was getting. I still wonder, though. The hum is really still there, going from the DTV receiver into my pre/pro via HDMI, although I am no longer hearing it. I am surprised it isn't causing any video artifacts, actually. Guess I am good for now...
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