Positional motorboating on amp channel—help?

[Blumlein 88]

Infuriatingly enough the damn problem seems to crop up at some times then mysteriously vanish—however when it recurred this last time I tried the quarters and it seemed to attenuate considerably. Then I went to the garage and got some pure copper washers, and when I stacked a few of those on the right hand side the noise vanished completely. Maybe something about the nickel content of the quarters, or the oxides on their surfaces?

Regarding the influence of the tubes, I verified that when in solid state mode, the tube circuit is powered down and bypassed—that’s when the noise isolates to the right channel. When the tube stage is engaged and the little bastards light up (augmented by a row of LED lamps surrounding them by the way), the noise jumps to the left channel. So I don’t think the tubes are likely contributing to the problem in and of themselves.

Whatever, your idea worked. My sincerest gratitude.

Okay. These things have to be laughed at or we'd curse the audiophile gods. It pretty much has to be a grounding problem, but if the washers work, then use the washers. You can likely work out some way to link the two chassis with a wire or something, but if the out of sight washers don't bother you then hey good enough.

 

[srkbear]

Okay. These things have to be laughed at or we'd curse the audiophile gods. It pretty much has to be a grounding problem, but if the washers work, then use the washers. You can likely work out some way to link the two chassis with a wire or something, but if the out of sight washers don't bother you then hey good enough.

Washers it is!

 

[srkbear]

Okay. These things have to be laughed at or we'd curse the audiophile gods. It pretty much has to be a grounding problem, but if the washers work, then use the washers. You can likely work out some way to link the two chassis with a wire or something, but if the out of sight washers don't bother you then hey good enough.

Forgive my obvious ignorance by the way, but is there a reason that the XLR cables don’t link the two chassis together themselves? Aren’t the sleeves grounded to the chassis? Please be gentle…

 

[SKBubba]

Eliminate pontoon boats, pickup trucks and beer?

 

[Blumlein 88]

Forgive my obvious ignorance by the way, but is there a reason that the XLR cables don’t link the two chassis together themselves? Aren’t the sleeves grounded to the chassis? Please be gentle…

Hard to know for sure without having hands on them. It should unless you have XLR's that the third pin isn't connected or has lost connection. Or somewhere that the 3rd pin is connected has lost clean contact with the chassis.

It occurs to me that you likely aren't using the RCA jacks on either device. You could take a cheap RCA cable and clip the center pin connection at one end. Then plug any two RCA jacks together so the outer ground part of the RCA plug connects the two together. That is all it would be a ground to ground connection for both pieces of gear. However if the outer shell of either piece of gear isn't connecting well to ground it might not help. If it works it is a little neater than a stack of washers.

 

[sq225917]

Crocodile clip leads are your friends. Personally I'd be wrapping a little mylar tape around the outside of that hdmi? socket below the two dc power pins on the ifi and also checking for xlr to chassis continuity.

 

[srkbear]

Crocodile clip leads are your friends. Personally I'd be wrapping a little mylar tape around the outside of that hdmi? socket below the two dc power pins on the ifi and also checking for xlr to chassis continuity.

Thanks for your suggestion! Inexplicably the problem seems to have magically resolved on its own—keeping my fingers crossed that it stays that way!

 

[JayGilb]

Thanks for your suggestion! Inexplicably the problem seems to have magically resolved on its own—keeping my fingers crossed that it stays that way!

No room for a bigger desk so you don't have to stack ?

 

[PatentLawyer]

 

[sq225917]

Just as an aside I have on several occasions found gnd loops to be caused by the outer metal work on various connections making contact with the chassis, hmdi, usb and incorrectly terminated xlr.