Damn ground loop - sorry, can't diagnose myself :(

Pycroft

So what's the fix? Go with the 3 prong to 2 prong adaptor removing the ground? Or is there something better?

James

Pycroft

I need to hit the hay. I'll check back in the morning. Goodnight Polkies - thanks for the help.

James

Dennis Gardner

Pycroft wrote: »

So what's the fix? Go with the 3 prong to 2 prong adaptor removing the ground? Or is there something better?

James

That is the answer, if you don't want to use the adaptor, get a PS Audio cable that has a removable ground prong.

I am only commenting because I had the same issue just yesterday and went through the same process. All of my gear was plugged into the same conditioner and still had a hum on the amp by itself. The hum came through the RCA cables even when all other gear was turned off and unhooked. It was the coax to HDMI to RCA route that allowed me to find it. my Coax ground is 50 foot from my HT room.

treitz3

Pycroft wrote: »

Okay, No buzz when done separately. Next step?

Connect the both of them with just the CDP hooked up as a source like you normally would. Ground loop rear it's ugly head?

Tom

Dennis Gardner

This is an example of what PS Audio has used for years. The ground pin is meant to be screwed out if needed.

billbillw

EDIT: Man, I thought for sure that the M6i had a tube preamp section, but when I looked into it, it does not. Forget everything I said about tubes.

Pycroft

I connected the 3 prong to 2 prong adaptor, and the buzz is no longer present when switching to the HD bypass. I won't have a chance to try it out by playing a blu ray into it until tonight. Any negatives with using the adaptor?

James

kevhed72

The issue I have was having 3 amps - a sub, a Parasound amp, and an AVR, all plugged into the same circuit all using grounded power cords. After using a power cable (s) with the ground un-used (or no pin), the problem went away.

Side note - i just saw on Audio Advisor a 'new' Pangea cable w/ removable ground pin...the AC-14XL I believe.

Pycroft

DARNIT -

It didn't buzz because I forgot to put the IC's back from the M6i to the preouts of the AVR. When I did, the buzz returned Am I doomed? Do I need a 3 prong to 2 prong for the M6i? Isn't that dangerous having that with no ground and plugged directly into the wall? It doesn't buzz with anything else but the darn AVR. GRR.

Thanks,

James

Pycroft

Well, isn't the ht bypass the only place that its meant to go??? That way the avr bypasses the controls all 5 speakers of the system and bypasses the controls of the integrated relating to the 2 speakers it powers?

As I posted yesterday, there is no buzz when it's on the aux switch, it just buzzes on ht bypass.

James

Pycroft

I plugged it into the tape and got no buzz in tape. Also switched to th ht/aux to see if it buzzed with nothing plugged in. It did not buzz.

James

Pycroft

Nope. I have an iPhone, but no cable. My hk avr 354 has a connection for iPod that goes directly to the avr, which I'm guessing won't work.

James

Pycroft

I won't be able to leave until later. As another diagnostic, I found a second 3 prong to 2 prong adaptor and plugged it into the amp which is plugged directly to the wall. No buzz at all anymore. Is that enough diagnostics?

James

Pycroft

Thanks for the help...unfortunately it will be a while until I can do this. I'll check back later.

Thanks,

James

tonyb

I was going to say try that cheater plug on the AVR, but it seems you have it licked...so far anyway. As far as long term effects, I've had a cheater plug on one piece or another for well over 5 years running now with no ill effects.

Pycroft

Okay -

I bought the wire, hooked my IPAD up to the HT Bypass. I also undid the cheater plug, so it was direct into the wall. No buzz - so I'm guessing we've eliminated that it's a problem with the integrated. I'm leaving for family party. Is this it for diagnosis? Is it best to just use the two cheater plugs? Is there something else to try? If so, I can try tonight - probably after 9pm I'll be back on. Thanks

James

Speedskater

Bill Whitlock has a complete troubleshooting section in this 2012 seminar paper:

"An Overview of Audio System Grounding and Interfacing"
by
Bill Whitlock, President
Jensen Transformers, Inc.
Life Fellow, Audio Engineering Society
Life Senior Member, Institute of Electrical & Electronic Engineers

http://centralindianaaes.files.wordpress.com/2012/09/indy-aes-2012-seminar-w-notes-v1-0.pdf

Polkitup2

I have had a ground loop in my system for years when using HT bypass. I have had 3 different pre amps and 2 AVRs, different amps etc. but always a hum when using HT bypass (except if I lifted ground). The answer for me was an IsoMax CI-2RR. No hum now.

Pycroft

I'm back home...I guess the diagnosis is over?

James

Pycroft

Bumping this for Tom or Ken or anyone with specific comments. I've done all tests asked (see above). Is there any other diagnostic that I need to do to satisfy those of you in the know, let me know. If not, is the only remedy to keep the two cheater plugs (one for the amp, and one for the AVR), or is there something else I should try first?

Tanks all.

James

leftwinger57

I had a gnd loop hum when I built my own rack and shelves to fit some of my gear that are the standard 19'' about 4 years ago. I used angle iron w/ holes so I could place L brackets to hold the shelves for the gear that was not rack mounted. I also tried the gnd plugs and the process of elimination and what my problem was that I bundled all my a.c. cords together on one side away from the source or low voltage wires. Whether I tightened the ty-raps to tight or had to much ac running parallel I'm not positive but once I dismantled that rack and started to use the rack I have now the hum had disappeared. All my gear runs through the Samson PS-15 9 outlet surge protector w/ the exception of the t.v. and the cable box and addionally none of gear has removable power cords.

Pycroft

Ken,

One other quick question before I do.

I'm currently using a Pangea upgraded power cord. Should I go back to using a stock cord? Does removing the ground make it pointless. I also heard that an amp should go directly into the wall, not using the power conditioner. If I'm removing the ground, should I now run it thru the power conditioner?

James

kevhed72

All this talk about cheater plugs, when a hack-saw will accomplish the same thing. I would always just saw-off the ground on the extension cords I used for the Christmas lights at our house in Illinois. That house caught fire for some reason.

On a serious note, I have my HT amp and sub both using upgraded power cords which have the ground wire disabled. No issues at all and I will usually keep both on - plugged right into the wall.

tonyb

Pycroft wrote: »

Bumping this for Tom or Ken or anyone with specific comments. I've done all tests asked (see above). Is there any other diagnostic that I need to do to satisfy those of you in the know, let me know. If not, is the only remedy to keep the two cheater plugs (one for the amp, and one for the AVR), or is there something else I should try first?

Tanks all.

James

James,
Ground loops are probably the most aggravating thing about audio. Normally, disconnecting everything and re-connecting one thing at a time helps to narrow it down. Usually too many grounds on one circuit causes the hum so lifting a few grounds on a piece or 2 won't hurt things. Sometimes it's a cable box, other times a bad interconnect or power cord, even those power strips people use can cause a hum themselves.

Always start with a good power conditioner, not those cheap strips sold at big box stores. Use well built cables as your interconnects and power cords. Also, a hospital grade receptacle in the wall is a good idea if your house is on the older side or you live in an apartment. Don't coil any of your cords, or bunch power/speaker/IC cords together. Avoid sawing off ground pins on power cords, that's what a 2 buck cheater plug is for. If you have to use a cheater plug, don't lose sleep over it, you won't damage anything and your house won't burn down. Good luck to you and others looking to quiet those gremlins.

Pycroft

I did replug everything, watched Band of Brothers first two episodes, put on some Sarah Vaughn on CD, and played 'Tommy' by The Who on Vinyl - No hum. Two cheater plugs...grr Thanks for the help in diagnosing everyone!

James