Ground loop issue on tube amp causing faint buzz?

[bajaed]

My Rogue Cronus Magnum is working and it sounds incredible! Beautiful, deep sound stage.

I may have an interference/ground loop problem. When no music is playing, I'm hearing a mild to moderate hum or buzzing. The amp is in a shelf just under my TV and behind it is a power strip that the TV, BR,AVR and Rogue are all plugged into. There is also an amp right behind the Cronus that the cable company installed to boost my signal(would it be the main suspect?).

A couple feet to the left is a separate outlet that my turntable is plugged into. A couple feet to the right is an outlet the cordless phone is plugged into along with one of those small 2" desktop fans I was using to pull heat away from the amp.When i turned the fan off I heard a click through the speakers but the buzz remained.

Does this sound like a grounding issue or could it be a bad tube? Like I said, music sounds great just noticing the buzz when it's quiet.

I have a pro coming over this week to check my setup and get it dialed in. Could the buzz hurt anything in the meantime? Any ideas as to the culprit?

 

[Dadbar]

Do you have TV sound hooked up to your system? Try disconnecting the cable and see if the buzz goes away. If so you may need a ground loop isolator. I had to insert one in my system. You can get one at MCM or Parts Express.....and probably at RadioShack.

 

[bajaed]

I do have an AVR. I just moved things around yesterday to hook up the Rogue. The AVR is plugged in and has speaker wires for the CC and rear surrounds that are all connected to it but not the speakers at this time.

I also have an optical audio cable plugged into the BR but not onto the AVR. Not sure if any of that could cause interference.

I bought a new RCA gold plated cable at Radio shack for running audio from the BR to the Rogue. I was having a heck of a time keeping them plugged all the way in. I was getting low volume from the right speaker till I reached around back and pushed it in farther on the back of the BR.

Just throwing out all the things I can think of that might be causing this.

I also bought an IR extender so I can operate my cable box and BR which are now in a wooden cabinet with a solid wood door. I've not hooked it up yet but was wondering if that might cause interference also?

 

[cademan]

The buzz won't really hurt anything except just being annoying. I'm not familiar with the cronus amp, but if it has a plug where both spades are the same size, try reversing it.

 

[heath2832]

A couple feet to the right is an outlet the cordless phone is plugged into....

My tube amp will pick up extraneous noises from my cell phone and cordless phones if close enough to the amp.

 

[JBCobra]

I had a 12ax7 tube that was causing a shight hum. Drove me nuts things trying different things until I found the noisey tube

 

[Thespeakerdude8]

The buzz won't really hurt anything except just being annoying. I'm not familiar with the cronus amp, but if it has a plug where both spades are the same size, try reversing it.

To this effect, does your amp by chance have a three prong cord? if it does, try a cheater plug to lift the ground...although a buzz sounds more like a switchmode power supply somewhere near the amp is putting dirt into the line.

 

[bajaed]

Found the source of the buzzing, it's the TV. 60PS60 LG Plasma. When it's off, the amp is dead silent, only buzzes when the TV is on.

What do I do?

 

[cademan]

Move the amp!

 

[bajaed]

Next to impossible to move it unfortunately, any other way?

Would a better power cord or power strip help or is this likely coming from inside the TV.

 

[cademan]

What you are getting is electrical interference from the TV's power supply (and flyback interference from tube TV's) so you have to isolate either the TV or the amplifier from each other.

 

[Dadbar]

Stupid idea....you might be able to put a shield between the two items and reduce noise...may depend on WAF. I would try putting a layer of aluminum foil between the 2 items and attach a ground wire to the foil. You could either put it under the TV or tape it to the shelf above the amp out of sight if the TV is above it. Cheap to try.