Yamaha Ground Loop


#1

Hey guys, I am banging my head around a possible ground loop.

My stereo system comprises of: DS senior DAC - Pass Labs XP30 preamp - BHK300. All of them fed by a P10.

To multichannel, I am using a Yamaha RX-a3060 receiver. The power section of the receiver goes to center and surround channel, and the preamp section of the receiver goes into de Pass Labs preamp.

The problem is that I get a 120hz buzz when I select the input to which the receiver is connected. The buzz varies with the volume, all indicating a ground loop. I have no issues with the DS DAC. Dead quiet, using either XLR or RCA. Tried changing cables, moving the receiver around etc.

The problem I think lies in that the receiver is class 2 device (double insulated), using a 2-prong AC cord, and no ground connector at the chassis. The only ground connector is for the phono input. Should I connect a grounding wire to this phono input? Or should I open the receiver case, and look for the star grounding point (if there is any)? Or is there any other approach I can use?

By the way, I can replicate the problem with others 2 prong AV receivers borrowed from close friends.


#2

I had the very same problem. I used an isolation transformer. My setup is all balanced and went with this:

https://www.amazon.com/gp/product/B0002DUQ72/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

Worked perfectly! BTW, I thought the ground lift switch might be useful but didn’t matter.


#3

Thank you for the tip. This transformer should go to between the receiver and the p10?


#4

What’s connected to the receiver?


#5

It’s a line level transformer he’s suggesting used on the audio ins and outs on the receiver. Not the AC.


#6

2 HDMI cables: one coming from a HTPC and the other going to my Sony projector (that is grounded). Thanks for the clarification about the transformer.


#7

Your stereo system by itself must sound fantastic, each component doing it’s intended job, when unencumbered by random inputs. You have some nice stuff there!


#8

Hey Ron,

Thanks for your comments. I must say that I am pretty pleased with the music. I have never imagined in my youth, living here in Brazil, that one day I would able to hear and enjoy such audio quality. It still amazes me every time I turn it on.


#9

just bought the isolation transformer. Once it gets on my chain, I will let you know if it is doing its job.


#10

If you bought the isolation transformer I posted, hope you noticed the phono inputs. I used these on the input of the transformer:


#11

Go fully balanced all the way. Ditch the receiver.


#12

@amsco15, thanks for the heads up. Yes, I had noticed the need for the plug adapter. Let’s see how it works out.

@quintanilla, thank you for your comment. But to go fully balanced I would have to go separates in my multichannel setup. That’s an investment I am not considering right now. For stereo, I am pretty meticulous with sound quality. For multichannel, all I want is clear voices for the dialogs and a good nice explosion in the action movies. Maybe someday I will take that step.


#13

Perhaps, I didn’t want to sound like an empty comment without some context. The Yamaha could still be useful if you shift its processor duties to one of these brutes.


#14

After some vactioning, I got back to my system. And indeed, the filter solved the problem. No more ground loop noise. Thanks again for the comments and this.