Ground Loop Help

jeremymarcinko

I need some advice, I recently replaced an aging 2ch yamaha power amp w/ a 2 prong A/C cord with a new amp that has a 3 prong. Now I am getting some ground loop buzzing from the main speakers when I turn on my plasma tv which has the only other 3 prong in the system. I have a tried the cheater plug and it works but is it ok to use? I dont want to damage anything of course. Or would a power conditioner solve this? I looked at the Panamax 4300 that was suggested on another thread but would like a quick yay or nay before I purchase.
Thanks

Habanero Monk

All equipment plugged into the same outlet?

jeremymarcinko

yea I tried plugging the amp in on the next outlet down on the wall but still buzzed. I pretty sure everything on that wall is on the same circuit.

Habanero Monk

Ground is referenced at the outlet so hum could still exist on same circuit but multiple outlets. Can you plug everything into the same outlet for testing purposes?

jeremymarcinko

Tried it made no difference.

Habanero Monk

Generally having everything in the same outlet will fix ground loop. Is there a Cable Box plugged in? Other than that you will have to use a cheater plug.

If you get the Panamax make sure you can return it if it doesn't work.

jeremymarcinko

No cable, only a ps3 and my antennea cable into the tv, made no difference disconnected. The buzz is only present with the both the tv and avr on at the same time. avr&amp no buzz, tv&amp no buzz, tv+avr+amp=buzz. It seems the ground loop is created thru the hdmi cable and interconnects as the tv and amp are not seeing each other until the avr is powererd up. My thinking is the cheater plug will be ok to use since the amp will stay grounded thru the tv but if I turn the tv off for music listening the amp would be ungrounded. I may give the panamax a try.

zane77

Did you try running a separate ground wire tied to the chassis of all three pieces? Sometimes that will get rid of a ground loop.

jeremymarcinko

No, but I like that Idea. I will give it a try

jeremymarcinko

Ha, Thanks Zane, it worked. No more buzz.
You too Habanero I really appreciate the help

zane77

Glad that took care of your problem and happy I could help someone out after all the help I have found on this forum

zingo

Very good suggestion, and congrats on losing the buzz!

ZLTFUL

Just wanted to add some insight into this issue.

So one thing you have discovered is that not all grounds are created equal.
When plugging 2 3 pronged plugs into the same outlet (mind you we are NOT talking about a power conditioner like the Panamax as they have circuitry to "balance" the ground"), they vie for dominance. Since the grounds are never the exact same negative voltage for a multitude of reasons, the "stronger" ground takes over and it usually creates hum of varying degrees.
In grounding the chassis of the 3 devices together, you have done essentially what a device like the Panamax does. Obviously, it also does more than that but it also helps balance the ground between the common and floating ground devices.

Having dug for days trying to track down and kill my own ground loop hum and finding that nothing I did got rid of it, I nearly slapped myself silly when I realized that my sub (with a 3 pronged plug) and my power conditioner while plugged into different outlets, were on the same circuit and were fighting to be the biggest baddest grounded device in the circuit. Simple fix was plugging my sub into the power conditioner. Hum was gone, angels sang, life was once more happy.

jeremymarcinko

I think I will still get the panamax though. Upon further investigation I am still getting a very slight buzz from all 5 channels but can only be heard with my ear as close as 4-5 inches from the tweeters any more and I cant hear it. Not a hiss but a buzz that is there if the avr is on, no matter if the tv or is on or even connected. Zanes suggestion definitely worked the previous buzz could be heard 9 ft away in a silent room and was consistent with the TV. The brighter the screen the louder the hum. The noise I am hearing now could of always been there even with the old amp and I never noticed it.

tonyb

zane77 wrote: »

Did you try running a separate ground wire tied to the chassis of all three pieces? Sometimes that will get rid of a ground loop.

That was the old school way, we used to do that especially on TT's, RTR's.

A 2 buck cheater plug will work for most applications. Also some cables are more prone to ground loops than others, IC'S specifically. As far as safety on a cheater plug, have one in my system on my amp now for about 5 years now with no issues. Grounding will still happen between pieces by cables to some degree.

Speedskater

I won't quote 'ZITFUL's' post, but electricity in the real world just doesn't work that way.

Three excellent papers on how electricity really works.

Power and Grounding For Audio and Audio/Video Systems -- A White Paper for the Real World
http://www.audiosystemsgroup.com/SurgeXPowerGround.pdf

UNDERSTANDING, FINDING, & ELIMINATING GROUND LOOPS IN AUDIO & VIDEO SYSTEMS
http://www.jensen-transformers.com/an/generic%20seminar.pdf

Power Distribution and Grounding of Audio, Video and Telecommunications Equipment White Paper (986 KB)
http://www.middleatlantic.com/power.htm

zane77

Tony, what can I say I'm getting old! You sound like my wife, LOL!

zane77

That is also how we eliminate grounding problems in current generation CT and MRI scanners and for patient safety by not having chassis floating above ground potential

PolkieMan

Very nice papers on how electricity really works. Thanks!

zane77

Great references Speedskater

ZLTFUL

Actually speedskater (the screen name is ZLTFUL btw) my statement is from the Jensen paper. Specifically the comment that points out that earth grounds are not 0 volts.
Perhaps you read my post completely an entirely wrong but the Jensen paper goes on to further reinforce what I was saying by "common" grounds being anything but.

Habanero Monk

jeremymarcinko wrote: »

I think I will still get the panamax though. Upon further investigation I am still getting a very slight buzz from all 5 channels but can only be heard with my ear as close as 4-5 inches from the tweeters any more and I cant hear it. Not a hiss but a buzz that is there if the avr is on, no matter if the tv or is on or even connected. Zanes suggestion definitely worked the previous buzz could be heard 9 ft away in a silent room and was consistent with the TV. The brighter the screen the louder the hum. The noise I am hearing now could of always been there even with the old amp and I never noticed it.

That could be gain induced hiss from the amp. unplug the inputs from the amp and see if the noise goes away. Then if you have multiple sources connect one at a time and see if one, more than one, or all give you hiss. Is this hiss coming out of the tweeter?

jeremymarcinko

Yea, there is a slight hiss very faint from the tweeters, but the buzz has now been eliminated. Zanes suggestion worked almost completely the first time around. But I went back and rewired the chassis grounds with heavier 12ga wire and terminated ends and connected to the ground at the outlet, which completely eliminated any audible ground noise. The first time I just used some thin 18ga wire for testing purposes and it left some faint buzz in the tweeters. Now the hiss I am not to concerned about I can only hear it with my left ear an inch away from the tweeters and its dead quiet if I put my right ear up to the tweeters. So I can imagine in a couple of years this hiss will go away on its own.:rolleyes: I did order the panamax as well but haven't received yet, crutchfield has the 4300 on sale for only $199 so figured it can't hurt and I like the thought of seeing the incoming voltage right there on the lcd.

daboyz

Good decision on the Panamax. The single best way.