Is my hum a ground loop?

[Uniquely]

I have an Onkyo 606 that is about a year and half old. I have developed a hum in the past month or so. It comes from all four surrounds, but is not noticable in the mains or the center. It is louder in the right surrounds. It is louder in matrixed options like PLIIX than it is in true multi-channel soundtracks like DD. It is non-existent when the receiver is not receiving an audio track, like when changing channels on the satellite receiver or in the start of a DVD when the warning screens come up.

I have not changed anything in the wiring situation... so there are no electrical wires any closer to the speaker wires than they were before the hum started. I do have one HDMI cable that is plugged into the back of the receiver that is not plugged into a source... but again that was the case before the hum started.

Does this sound more like a ground loop, or an issue with the receiver?

[solarrdadd]

have you tried disconnecting all input and output sources with nothing connected except power and speakers and see if you have the noise? if you do that and the noise goes away, try connecting your gear, on connection at a time until it starts again.

it sounds more like it's a problem with your receiver or your satellite box to me. most of the time (but not all of the time) a ground loop will effect all of the active speakers and i'm surprised when you say you don't hear it in the front 3 soundstage, it's usually most obvious there from the amout of sound that comes out of them. also a real good ground loop would produce hum even when selecting an input where there is nothing connected to it or when you have nothing connected to the receiver, just speakers (so you can hear the hum).

i am of a mind that it's your satellite box or your receiver. i'd start with them. try disconnecting your satellite box and see if the hum still exist. if it stops your home free. if it doesn't try disconnecting your dvd player, if it stops your home free, if it doesn't and you disconnect everything then you have a real good problem. next thing would be to unplug the satellite box from the wall power.

i think you get the idea, give those things a try and get back to us. also has anything happened around or near your house or apartment in the time you mentioned this hum started like cable or electrical work or something? is your satellite cable grounded properly before it enters your house? it should be connected to either a driven ground rod or a copper or steel cold water pipe.

get back to us.

[srrndhound]

Originally Posted by robinandtami

It is non-existent when the receiver is not receiving an audio track, like when changing channels on the satellite receiver or in the start of a DVD when the warning screens come up.

So anytime you mute the audio, the hum goes away? That suggests it is not ground loop.

Does this sound more like a ground loop, or an issue with the receiver?

Hard to tell if the hum is generated inside the AVR or induced into it from an external field like a TV or other device nearby. Try turning everyhing but the AVR off, assuming you can usually hear the hum from a silent analog input.

[Uniquely]

I really haven't tried anything yet. Disconnecting and reconnecting is going to require A LOT of elbow grease. Everything except my PC is connected by 6ft hdmi's so they BARELY reach the back of the receiver. I was almost hoping that someone would say.... "yep... it's definitely the receiver." When I do get a new receiver I plan to get longer hdmi's as well to make connection much easier. As it stands now... I'll have to dismantle my whole twelve foot ent unit to play with the connections. That's something I really only wanted to do once... and for good reason, like a new AVR.

[Uniquely]

Originally Posted by srrndhound

So anytime you mute the audio, the hum goes away? That suggests it is not ground loop.

Hard to tell if the hum is generated inside the AVR or induced into it from an external field like a TV or other device nearby. Try turning everyhing but the AVR off, assuming you can usually hear the hum from a silent analog input.

Yes.... if I mute there is no hum. Also... there is no hum if there is no active audio track being sent to the AVR; like when switching channels or in the warning screens of blues.

[LordoftheRings]

Originally Posted by robinandtami

I have an Onkyo 606 that is about a year and half old. I have developed a hum in the past month or so. It comes from all four surrounds, but is not noticable in the mains or the center. It is louder in the right surrounds. It is louder in matrixed options like PLIIX than it is in true multi-channel soundtracks like DD. It is non-existent when the receiver is not receiving an audio track, like when changing channels on the satellite receiver or in the start of a DVD when the warning screens come up.

I have not changed anything in the wiring situation... so there are no electrical wires any closer to the speaker wires than they were before the hum started. I do have one HDMI cable that is plugged into the back of the receiver that is not plugged into a source... but again that was the case before the hum started.

Does this sound more like a ground loop, or an issue with the receiver?

Unplug that useless HDMI cable.

Originally Posted by robinandtami

Yes.... if I mute there is no hum. Also... there is no hum if there is no active audio track being sent to the AVR; like when switching channels or in the warning screens of blues.

Try this: Change the interconnect going to your sub, just to check.

* Your 606 might have a internal issue!
But before we get to that point, let's just check all the other possibilities first.
A good place to start is the wiring (speaker cables and interconnects);
and a good way to proceed is to disconnect ALL the wires, and plug them one at a time with always checking how it sounds. ...You know, one source at a time...
Another thing: make sure the AC power cords don't interfer with speaker wires and interconnects; if they have to cross some of them, make it at a 90 degree angle.
Another thing: watch for too close antennas (radio, tv, etc.).
Another thing: try to reposition your receiver further from your TV.
Another thing: do the same from the Cable box or Satellite box.
Another thing: a triple-shielded interconnect for the sub is a good idea (double-shielded at least).

Try there first, I got several other alternatives... Till next time though, after you tried those first.

Bob

[srrndhound]

Originally Posted by robinandtami

I really haven't tried anything yet. Disconnecting and reconnecting is going to require A LOT of elbow grease. Everything except my PC is connected by 6ft hdmi's so they BARELY reach the back of the receiver. I was almost hoping that someone would say.... "yep... it's definitely the receiver." When I do get a new receiver I plan to get longer hdmi's as well to make connection much easier. As it stands now... I'll have to dismantle my whole twelve foot ent unit to play with the connections. That's something I really only wanted to do once... and for good reason, like a new AVR.

Since you've already confirmed that the hum is not due to a ground loop, there's no longer any need to disconnect anything. Now you have to find out how the hum is being induced into the audio path. The source is either the innards of the AVR itself (indicating some sort of defect), or it is some external device such as a display or anything else that uses AC power nearby.

Because your hum goes away when bitstreams are stopped (it's muting the audio same as if you use manual mute) you have to use an analog input for further testing. Your next step is to power down all the associated gear and anything else plugged into an AC outlet in proximity to the AVR.

After that, if the hum remains, you may as well start removing the various audio/video cables, as you are likely to find one of two things at that point:

a) the hum remains with everything disconnected--the AVR needs repair or replacement, or
b) the hum goes away so it was in fact caused by some external connection, and that needs to be changed in some way after all.

Switching off the power is the easy, non-invasive thing to do, so it's where I'd start the process.

[Big Daddy]

robinandtami,

Check the following thread. It may help.

https://forum.blu-ray.com/home-theat...isolators.html

[Uniquely]

Thanks for the suggestions guys. It was coming from the satellite box. When I disconnect the HDMI from my sat box there is no more hum on my BR player or xbox. I guess the next step is to get Dish out to check the cabling. Wouldn't there be a hum on my other sat boxes too? I have not noticed one in my other two sound systems.

[Big Daddy]

Originally Posted by robinandtami

Thanks for the suggestions guys. It was coming from the satellite box. When I disconnect the HDMI from my sat box there is no more hum on my BR player or xbox. I guess the next step is to get Dish out to check the cabling. Wouldn't there be a hum on my other sat boxes too? I have not noticed one in my other two sound systems.

Satellite, cable boxes, computers, and dimmer switches are the primary causes of noise problems. If plugging to other wall outlets and switching cables do not work, you may have to buy a ground loop isolator such as Hum X. All the links are in the thread I mentioned above.

[LordoftheRings]

A ground loop isolator, as suggested by Big Daddy is your ticket.

Another solution you can try is to connect your Satellite box to another AC outlet or the same AC outlet as your other components. Just check both ways that's all, and if all fails, then, just as mentioned above here.
...Or that HDMI cable from this particular component.

* As for your other Satellite boxes, and your other systems; it's hard to tell because each one of them if not different, use different paths in your electrical system. ...And the way various components interact between each other... Positioning, etc.

[DiverSpear]

The reason those particular sat boxes/cable cause a hum is in the order of harmonics. The most common being 3rd, 7th, and 11th order. The harmonics are caused when electronics introduce noise into the electrical system as seen on an o'scope. Usuallly on the grounded conductor. Good filtering, i.e. power conditioners help. I have Directv and my system isn't ground properly, I cut it with the weed wacker LOL, but I do not have any noise issues. If I develop any I will ground the satellite in accordance with the NEC, until then I'm lazy and it's my house. LOL

[LordoftheRings]

Originally Posted by DiverSpear

The reason those particular sat boxes/cable cause a hum is in the order of harmonics. The most common being 3rd, 7th, and 11th order. The harmonics are caused when electronics introduce noise into the electrical system as seen on an o'scope. Usuallly on the grounded conductor. Good filtering, i.e. power conditioners help. I have Directv and my system isn't ground properly, I cut it with the weed wacker LOL, but I do not have any noise issues. If I develop any I will ground the satellite in accordance with the NEC, until then I'm lazy and it's my house. LOL

Hmmm... Quite interesting indeed. ...Harmonics!