Audio Emotion  Epiphany Acoustics 
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  1. #1
    Wammer
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    Ground Loop Isolator Needed

    Guys

    My newly aquired Usher 1.2 appears to have a bit of a ground loop problem. The amp is at one end of the living room whilst the pre-amp is in the dining room with the rest of my equipment. Obviously they are both using different mains sockets. When nothing is playing through the amp there is a constant low buzzing sound coming out of the speakers. Dynamic Turtle who I bought the amp off told me he had a similar problem that was cured using a ground loop isolator.

    My questions are what do I need to do to stop the ground loop noise? Can I just buy an isolator off eBay? Is there a better option?

  2. #2
    Pac67
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    I'd strongly advise NOT using an Ebay "special" ground loop isolator. They're cheap and whilst they do isolate the ground loop effectively, they also kill frequency response, especially bass response. A decent 1:1 transformer based GLI costs a lot of money (£300 plus), but the cheaper ones just don't cut the mustard. My advice would be to run a long (bespoke) mains extension lead from your main equipment mains block to your amp so that all components are hooked up to the same supply outlet. That should help.

  3. #3
    Wammer
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    Cheers Pac! That was the other option and the one ill follow up!

    Sent from my Dell Streak - excuse the spelling mistakes!

  4. #4
    Moderator myrman's Avatar
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    I would suggest that anyone contributing to this thread be aware of the AUP.

    You will not post any recommendation to modify any part of an electrical installation or the mains power supply of equipment or anything connected to it, including fuses, plugs and cabling.

    Thank you.

  5. #5
    Too many turntables Beobloke's Avatar
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    If you need to isolate a ground loop between the pre amp and amp, then the Supra AGS-10k should do the trick. About £100 IIRC.
    Instant human being - just add coffee. Do not stir.

  6. #6
    Super Dooper Wammer Cable Monkey's Avatar
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    How much would it cost to get an electrician in to check your earthing is properly provided?
    Let me get this straight. You take a perfectly good CD and put it in a DVD player??!!

  7. #7
    Gufmeister Leonard Smalls's Avatar
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    Are both mains sockets on the same circuit? If it's the same ringmain, both should have virtually identical earth paths, which would mean any potential differences would be incredibly small. If they're on different circuits there still shouldn't be much difference either as both should be earthed to the same point in your consumer unit.
    I'd have it checked out - a good electrician should be able to test the earthing of all sockets involved within a couple of hours. Make sure the sparky is qualified to inspect and test - i.e. holds C&G 2391 or higher. I'd do it myself but I don't work as far as Cardiff!

  8. #8
    Wammer
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    Had same problem myself. Tried a cheapish group loop isolator. It was an 'ART Artcessories DTI, dual transformer/isolator'. Sorted the hum, but sounded shite, really distorted.

    In the end I fixed by swapping my amp, for one that wasn't bothered by different earths. :-\

    But yes, I really should get a sparky out to look at electrics too...

  9. #9
    Acc shut see Purité North
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    Just so no-one's tempted to dick-about with lifting Earth - there should be no direct connection between Mains Earth, and an amplifier's various signal circuit ground planes.

    This is one of the best accounts of the issue, and if you can't understand it - then that's a CERTAIN sign you shouldn't be dicking about with your amp!

    LEAVE THE MAINS ALONE!

  10. #10
    Gufmeister Leonard Smalls's Avatar
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    Excellent! Bit short on knob and fart gags though.

  11. #11
    Wammer
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    Quote Originally Posted by earlofsodbury View Post
    Just so no-one's tempted to dick-about with lifting Earth - there should be no direct connection between Mains Earth, and an amplifier's various signal circuit ground planes.

    This is one of the best accounts of the issue, and if you can't understand it - then that's a CERTAIN sign you shouldn't be dicking about with your amp!

    LEAVE THE MAINS ALONE!
    Looks interesting. EDIT: it IS an interesting read.
    Would you have anything similar about DC on the mains, current on the neutral line or suchlike?
    Last edited by uncl_nigel; 13-09-2011 at 06:22 PM.

  12. #12
    Wammer
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    Quote Originally Posted by earlofsodbury View Post
    Just so no-one's tempted to dick-about with lifting Earth - there should be no direct connection between Mains Earth, and an amplifier's various signal circuit ground planes.

    This is one of the best accounts of the issue, and if you can't understand it - then that's a CERTAIN sign you shouldn't be dicking about with your amp!

    LEAVE THE MAINS ALONE!
    Many thanks Earl. My Uncle Frank was a smalltime Welsh opera singer back in the 60's and 70's. He was appearing in a town near Swansea and had requested that there be no microphone on stage - he thought they were an insult to his abilities. When he walked out on stage a mic had been set up for him and Uncle Frank went to move it not knowing that it was to be the last thing he would ever do. As he touched the mic stand he was electrocuted and died on stage in full view of his audience. Consequently I have a healthy respect for leccy - and would certainly not have been planning on "dicking around" with my amp.

    Now to try the extra long mains cable.....

  13. #13
    Wammer
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    Hey Jon - sorry to hear about the GL issue - same problem here for years and sadly i couldn't afford the expensive bespoke solutions everyone is suggesting. Quality transformer GLIs were about £200 without interconnects. Getting an electrician in would've been expensive too. The GLI I sent you is a short term solution to get the amp working without serious compromise, but as the guys suggest, you might want to invest in a more audiophile solution for the longer term. The upside is that having proper sorted earths for the entire mains will probably have an accretive, positive impact on the sound, so I guess you should consider it as a system solution rather than just something to get the power amp maximised.

    I miss my system though. The flat is bare without it! Currently using an old dvd player, heaphone amp and cans. Sounds shite :-(
    SACD: Marantz Pearl Lite
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  14. #14
    Wammer
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    really interesting read thanks, and that's awful about your uncle frank!

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