2. amps-preamps
  3. 1347156354

Amp hums in standby mode when TV is on

Hi, my Sherbourn 5/1500A power amp starts humming whenever the TV in the same room is operating. This occurs even when the amp is in its standby state, and also happens when using the amp(although you can't typically hear the humming at that point because of the sound from the speakers). What's more, as the image on the TV varies in brightness, the intensity of the humming/buzzing also varies. If the TV is off, the amp is dead quiet. I am assuming this is some kind of ground loop problem.

Should I try to plug the amp in with a "cheater plug"? There is a sticker on the back of the amp that indicates that the amp must be used with a grounded power cord.
mtrot
vicdamone
850 posts
 
If your video system is connected to cable you may need to have your cable provider isolate the cable with a devise similar to the Jensen VRD-1FF.

http://www.jensen-transformers.com/iso_vid.html
mtrot OP
804 posts
 
Thanks! Yes, I do have cable TV service. Also, this amp hummed in the same manner when it was previously used in another room in the house. There is also a cable outlet in that room.
jea48
4,405 posts
 
Hi, my Sherbourn 5/1500A power amp starts humming whenever the TV in the same room is operating. This occurs even when the amp is in its standby state,
Mtrot
Mechanical hum heard from the amp not through the speakers?

If yes then I would assume the power transformer of the amp is energized in the standby mode.

Good chance the sound you are hearing is coming from the power transformer of the amp.

If the buzzing, mechanical noise, is coming from the power transformer (only when the TV is turned on) then there is a good chance the switching power supply, SMPS, of the TV is putting DC offset back out on the AC mains.

Verify the sound is indeed coming from the amp's transformer and not through the speakers.

If that is the case You will to buy a DC Blocker.
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unsound
7,329 posts
 
Sometimes careful cable dressing/orientation can help mitigate situations like this.
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