Ground loops and AVR's not having a grounded power cable

[Max2]

I picked up an amp earlier in the week and figured I would have a 60hz hum due to a ground loop in my old house and its wiring. When I lift the ground it drops to total silence with the adjustable input sensitivity maxed out. I have checked all the outlets with a plug checker and they show fine. I can unplug everything in my system and the room for that matter, plug the amp in and there is no 60hz noise. When I plug the RCA's from my AVR into the amp is when the noise starts and it does this without the AVR even being plugged into an outlet.   I noticed my Denon 4311 power cord had no ground plug and thought I used the wrong cord from my last move. I unplugged it from the unit and noticed the female outlet has no ground wire either.   I thought all AVR's came grounded these days. Anyone have any suggestions?

[billybob]

When I lift the ground it drops to total silence with the adjustable input sensitivity maxed out

What is meant by this please?

Do you have a surge protector to plug into that has ground plug?

Edited April 15, 2015 by billybob

[CECAA850]

Have a read.

 

http://web.mit.edu/~jhawk/tmp/p/EST016_Ground_Loops_handout.pdf

[derrickdj1]

That read is almost 50 pages, lol.  Get something like this: 

 

I use one and it works pretty good.

[Max2]

 

When I lift the ground it drops to total silence with the adjustable input sensitivity maxed out

What is meant by this please?

Do you have a surge protector to plug into that has ground plug?

 

 

I actually have two protectors that are both grounded and have tried using them in various ways and eliminating them.  One of them actually knocked some of the hum down, but not very much.  When I said lifting the ground, I simply tried a power cord that has had the ground lug removed.  

 

 

Im still hoping for an answer why high output AVRs aren't grounded. Im all about safety, especially when it comes to my little boy, but I find it strange we got by so many decades without using grounds. I guess some folks didn't. 

 

Have a read.

 

http://web.mit.edu/~jhawk/tmp/p/EST016_Ground_Loops_handout.pdf

 

Thanks. That's the most thorough read I have seen on ground loops.  

Edited April 15, 2015 by Max2

[Max2]

That read is almost 50 pages, lol.  Get something like this: 

 

I use one and it works pretty good.

 

This is a 5 channel amp and I would prefer not to use anything in the signal path, but thanks for the note.

[billybob]

Im still hoping for an answer why high output AVRs aren't grounded. Im all about safety, especially when it comes to my little boy, but I find it strange we got by so many decades without using grounds. I guess some folks didn't.

BTW, I have a nonground plug on a Denon AVR as well. Many units do not have them anymore counting on your surge protector, line conditioner to protect them.

Yes, safety is number 1...do you have another set of rca cords to try?

You could try grounding the chassis with a wire attached to a screw, just for the doing it.

[Max2]

 

Im still hoping for an answer why high output AVRs aren't grounded. Im all about safety, especially when it comes to my little boy, but I find it strange we got by so many decades without using grounds. I guess some folks didn't.

BTW, I have a nonground plug on a Denon AVR as well. Many units do not have them anymore counting on your surge protector, line conditioner to protect them.

Yes, safety is number 1...do you have another set of rca cords to try?

You could try grounding the chassis with a wire attached to a screw, just for the doing it.

 

 

 

Im hoping I get some relief from the RCA cables coming from Blue Jean later this week.  Im no electrician, but would I still be at risk if I used a ground eliminator even plugged into a surge protector?  My amp only pulls about 1 more amp than my AVR, it seems strange everyone says don't use a ground eliminator, yet modern AVRs pulling 8 amps still don't use them.  Im confused about this

[billybob]

Im hoping I get some relief from the RCA cables coming from Blue Jean later this week. Im no electrician, but would I still be at risk if I used a ground eliminator even plugged into a surge protector? My amp only pulls about 1 more amp than my AVR, it seems strange everyone says don't use a ground eliminator, yet modern AVRs pulling 8 amps still don't use them. Im confused about this

Try grounding the chassis of the AVR just for kicks.

Only reason to ask you to try another set of rca's is, it is easy to do.

I would be surprised if the new cable eliminated problem but...

You are always at risk when lightning or other line surges come to test your surge protector, regardless of grounded or ungrounded units are plugged into it.

Not an electrician either(former electronics for a number of years) Always proceed with caution.In

All I know is, a house ground has to be right in order to minimize risk to house and it's occupants.

[CECAA850]

it seems strange everyone says don't use a ground eliminator, yet modern AVRs pulling 8 amps still don't use them. Im confused about this

 

They're double insulated like a power drill for example.

[Max2]

 

Im hoping I get some relief from the RCA cables coming from Blue Jean later this week. Im no electrician, but would I still be at risk if I used a ground eliminator even plugged into a surge protector? My amp only pulls about 1 more amp than my AVR, it seems strange everyone says don't use a ground eliminator, yet modern AVRs pulling 8 amps still don't use them. Im confused about this

Try grounding the chassis of the AVR just for kicks.

Only reason to ask you to try another set of rca's is, it is easy to do.

I would be surprised if the new cable eliminated problem but...

You are always at risk when lightning or other line surges come to test your surge protector, regardless of grounded or ungrounded units are plugged into it.

Not an electrician either(former electronics for a number of years) Always proceed with caution.In

All I know is, a house ground has to be right in order to minimize risk to house and it's occupants.

 

 

 

Will do and thanks Billybob. will report the results later on tonight. New RCA's should be in tomorrow.

[babadono]

Have a read.

 

http://web.mit.edu/~jhawk/tmp/p/EST016_Ground_Loops_handout.pdf

Is that "Wild Bill Whitlock"?

Edited April 15, 2015 by babadono

[babadono]

Ah.......the "ground" connection on a piece of equipment, if there is one, is to protect YOU not the equipment. If current flows into this ground from the equipment there is already something wrong with it.

[NOSValves]

Here I get tired of trying to explain this. Ground loop can happen in freshly wired house by a AC wiring god. It has nothing to do with the quality of the house wiring. It can be made worse by poor wiring but poor wiring is not the root cause.

 

 See attached quickly scribbled out diagram.

Edited April 15, 2015 by NOSValves

[babadono]

I picked up an amp earlier in the week and figured I would have a 60hz hum due to a ground loop in my old house and its wiring. When I lift the ground it drops to total silence with the adjustable input sensitivity maxed out. I have checked all the outlets with a plug checker and they show fine. I can unplug everything in my system and the room for that matter, plug the amp in and there is no 60hz noise. When I plug the RCA's from my AVR into the amp is when the noise starts and it does this without the AVR even being plugged into an outlet.   I noticed my Denon 4311 power cord had no ground plug and thought I used the wrong cord from my last move. I unplugged it from the unit and noticed the female outlet has no ground wire either.   I thought all AVR's came grounded these days. Anyone have any suggestions?

Please let me dissect to understand. You acquired a new to you power amp and you intend to plug it into the preamp outs from your AVR? The amp has 3 prong power plug, the AVR is 2 prong. The amp is quiet when just it and the speakers are hooked up? Is this with the ground? Or with the ground lifted? When you plug the inputs from the AVR in the hum starts whether plugged in or not. Does it stay the same when the AVR is powered on? The outputs from AVR and inputs to amp are RCA type?

[DrWho]

Do you have a cable box connected to your AVR?

Btw, leakage current on the ground cable sounds like a ground loop, but is a different source of noise.

[muel]

Here I get tired of trying to explain this. Ground loop can happen in freshly wired house by a AC wiring god. It has nothing to do with the quality of the house wiring. It can be made worse by poor wiring but poor wiring is not the root cause.

 

 See attached quickly scribbled out diagram.

Sure that's not Dinah Mo you're hearing ?  

[Max2]

Here I get tired of trying to explain this. Ground loop can happen in freshly wired house by a AC wiring god. It has nothing to do with the quality of the house wiring. It can be made worse by poor wiring but poor wiring is not the root cause.

 

 See attached quickly scribbled out diagram.

Thanks. Im just worried I have a continuous ground from this room that may join another circuit to never be located.

 

 

 

 

I picked up an amp earlier in the week and figured I would have a 60hz hum due to a ground loop in my old house and its wiring. When I lift the ground it drops to total silence with the adjustable input sensitivity maxed out. I have checked all the outlets with a plug checker and they show fine. I can unplug everything in my system and the room for that matter, plug the amp in and there is no 60hz noise. When I plug the RCA's from my AVR into the amp is when the noise starts and it does this without the AVR even being plugged into an outlet.   I noticed my Denon 4311 power cord had no ground plug and thought I used the wrong cord from my last move. I unplugged it from the unit and noticed the female outlet has no ground wire either.   I thought all AVR's came grounded these days. Anyone have any suggestions?

Please let me dissect to understand. You acquired a new to you power amp and you intend to plug it into the preamp outs from your AVR? The amp has 3 prong power plug, the AVR is 2 prong. The amp is quiet when just it and the speakers are hooked up? Is this with the ground? Or with the ground lifted? When you plug the inputs from the AVR in the hum starts whether plugged in or not. Does it stay the same when the AVR is powered on? The outputs from AVR and inputs to amp are RCA type?

 

 

 

It is all silent until the RCA's are plugged in, then the hum starts.  And yes the humming is there whether the AVR is plugged in and turned on or left off.

 

 

Do you have a cable box connected to your AVR?

Btw, leakage current on the ground cable sounds like a ground loop, but is a different source of noise.

 

 

Im pretty sure its a 60HZ hum, but I could be wrong.  I do have Direc TV hooked up via HDMI through the AVR, but it makes no difference if it is on/off plugged in or HDMI unplugged from AVR.    The noise never comes until the RCA's are plugged in. I must say these RCA's Im using at the moment are cheapies, but I don't think they are the culprit

[babadono]

And the amp is 3 prong grounded? Or lifted? Or you have tried it both ways? And its all RCA to RCA?

[Max2]

And the amp is 3 prong grounded? Or lifted? Or you have tried it both ways? And its all RCA to RCA?

 

 

Correct. All RCA's. (mc 7205)  Hum is there with the grounded three prong. It disappears when I swap to a power cord with ground prong removed.