Ground Loop Hum

[chanlon]

Any of you folks find the Rotel 1570 prone to experiencing Ground Loop Hums?

Seems that the Oppo BDP-95 connected via multi-channel analog creates the ground loop with the Rotel processor. If I disconnect the RCA cables, the ground loop disappears. If I use a cheater plug on the Oppo, it disappears.

Recently I purchased an Shiit Audio headphone amp. The second I connect a RCA cable to the Rotel, a ground loop hum develops.

I have all power cables going into a pricey ISOBAR surge protector.

Satellite is disconnected from the Rotel and so is any internet connection.

Any suggestions?

[PewterTA]

You could tray taking a wire and connecting the two chassis together, Rotel and Schiit and see if the ground loop stops. If it does then you might have to create a ground cable to help.

This might also be the same thing for the Oppo.

[wkhanna]

With apologies to the OP for going off topic, I just ordered the Schiit Bifrost DAC. Curious as to your impressions on the headphone amp, chanlon.

[Kevin D]

Is there anything else connected to any part of your system that could be on a different power circuit? TV, subwoofer? You really need to disconnect EVERYTHING, then just the 1570 & amp. Plug the Oppo or headphone amp in, then everything else until you get the hum..

Chances are you always have the ground loop, and only the Oppo or headphone amp make it audible.

Kevin D.

[chanlon]

Thanks gang for all your responses. I'll try your suggestions and let you know how I make out.

Wkhanna - I PM'd you a response.

[chanlon]

Kevin, It is the subwoofer and TV that is the culprit.
They are plugged into a different AC receptacle in my family room.

The ground loop is louder when both TV and subwoofer and plugged in. Once I disconnect either one, its a little more livable. When neither are plugged in, there no ground loop.

So now what? :-) There is no way I can run a 20ft extension power cord to where my stereo is plugged in.

The TV (Pioneer 151FD Plasma's) only connection to the system is through a single HDMI cable (extra thick) that connects to the monitor output on the Rotel 1570. The subwoofer has a single 20FT RCA cable ran in-wall.

Any suggestions? Is there something I can do to potentially eliminate this humming?

Thanks again - it is so much appreciated!

[chanlon]

A ground loop isolator is on the way from monoprice for the RCA cable on my Sub!
I just read about HumX for the TV to plug into. Anyone out there try this product?
It's $80 in Canada - wowsers. Money well spent if it can straighten me out!

[jam200]

Here's a website with three reviews of the HumX.

http://www.americanmusical.com/Item--i-EBT-HUMX-LIST

Regards.

[Kevin D]

Yeah aside from isolating the ground from the signal, not much you can do except fix the problem.

Fixing the problem involves checking all the outlets involved for proper termination, included the rest of the outlets connected to each circuit. You can check and see if they if both circuits are grounded correctly in the panel.

If they are on different panels, check for proper grounding at the main panel and that the sub panel is grounded to the main panel and doesn't have its own ground.

If they are the same panel, you can try moving them to the same phase if they are not, or to different phases if they are..

Kevin D.

[Sackrat]

I had a similar HUM issue a few years ago. I spent about $8 on a ground loop isolator that resolved the problem immediately. It was all RCA plugs related in my case. Just offering a less expensive resolution that may or may not work for you as well. With some problems, cost is not object to get the result you want. Good Luck

[gp4Jesus]

$80! Ouch! You issolated the hum to your TV & sub. Good

Did you try running extension cord(s) to your TV &/or sub from where the rest of your system receives power? If hum stays away w/either or both connected there, that would support Kevin's comments about suspect house wiring. If not that device is your only solution.

Best to ya, tony

[Mark_C.]

It could be your satellite receiver that needs to be grounded. Even when not connected, if not properly grounded they can cause the problem.

[chanlon]

Guys, Can anybody out there verify whether or not the North American version of the Rotel RSP-1570 shipped with a 3-prong power cable or was it 2?

I have so many cables, I want to make sure I have the correct one attached to ensure I'm dealing with this ground loop correctly.

Thanks!

[chanlon]

I did run the extension cord so that the TV receives the same power and the hum does in fact disappear.

$80! Ouch! You issolated the hum to your TV & sub. Good

Did you try running extension cord(s) to your TV &/or sub from where the rest of your system receives power? If hum stays away w/either or both connected there, that would support Kevin's comments about suspect house wiring. If not that device is your only solution.

Best to ya, tony

[Kevin D]

Guys, Can anybody out there verify whether or not the North American version of the Rotel RSP-1570 shipped with a 3-prong power cable or was it 2?

I have so many cables, I want to make sure I have the correct one attached to ensure I'm dealing with this ground loop correctly.

Thanks!

Look at the back of the unit, if there's three tabs inside the plug, it shipped with a 3 prong. In addition, if it needed a three prong, a 2 prong wouldn't fit.

Pretty sure it has a 2 prong though.

Kevin D.

[madmac]

Look at the back of the unit, if there's three tabs inside the plug, it shipped with a 3 prong. In addition, if it needed a three prong, a 2 prong wouldn't fit.

Pretty sure it has a 2 prong though.

Kevin D.

I don't think there is a Rotel amp out there that does NOT have a 3 prong plug!!!

[Tom Caines]

Here's the Rotel back panel PDF. Looks like 2 prong.

[Kevin D]

I don't think there is a Rotel amp out there that does NOT have a 3 prong plug!!!

Huh?? It actually varies per product, but the vast majority seem to be 2 prong.

Kevin D.