6505+ buzz from output transformer

[::XeS::]

Today I turned on my amp and I immediately noticed a strange buzz from the output transformer.... a zzzzzzzzzzz in standby mode.
It always produced a soft hum when it was powered, but now it's a spiky sound....a weird buzz.
What could it be? Is it near its end? ....

 

[::XeS::]

Just miced the buzz with a sm57:
http://dl.dropbox.com/u/1436721/buzz.mp3

If you can't hear well, raise the volume

 

[kaomao]

have you had any work done to your power line by an electrician? installed at your place a new lamp/light? other electrical stuff that you hadn't before?
if not I don't know

 

[::XeS::]

No, not recently...the noise appeared this morning and yesterday evening there wasn't. I've just checked the tubes and they are fine...I disconnected everything but amp and speaker cable but the buzz is still there. Also tried different socket for the amp.

 

[::XeS::]

Sorry.....it's the Power transformer that makes the buzz (the one close to the plug cable)

 

[sprack]

How do you know it's the PT? If it was it'd most likely be somewhere in the fullwave rectifier or the filter's that'd allow an AC buzz through.

kaomao's suggestion is a good one. Bad ground especially. Try the amp at like a practice space or some place with an entirely different power grid.

 

[::XeS::]

It's the Power tranny because it makes phisically noise..it doesn't come from the speaker but from the tranny itself...I've read it's due to the laminates of the tranny that vibrate...
Kaomao's advice is good but the thing doesn't change from night to morning if it's a ground loop
The sample I posted was recorded micing the tranny at 4cm, not micing the speaker.

I've read that in case of vibrations, a solution could be tightening the tranny screws to tighten a little more the laminates

 

[::XeS::]

Anyone else?

 

[::XeS::]

I've just tried to tighten the 2 screw of the transformer but nothing changed.
The sound of the amp is still awesome, no additional hum from the speaker.....what scares me is the buzz of the tranny

 

[::XeS::]

Did some research and it could be a shorted power tube...checked them and they are all fine. I've just checked all the fuses and they are all fine...no blown fuses.

 

[::XeS::]

Just recorded another sample micing directly the tranny in standby mode:

http://dl.dropbox.com/u/1436721/Buzzz.mp3

 

[TheWinterSnow]

Have you put your hand on the transformer? If you press on it and the sound goes away, it is as you said, the laminates are loose. To me it sounds like something in the transformer is loose and is now acting like a transducer. If the part can't be serviced, you will most likely be looking at a transformer replacement surgery.

 

[::XeS::]

Yes I try that and nothing changed..I also tighten the screws but it still buzzes.

 

[::XeS::]

Anyway the only strange thing I could have done, before the problem appears, was to shut down the amp (by mistake) directly with the power button, without standby before. Don't know if it can cause something similar...

 

[voidar]

That's the way I was taught how to shut down an amp.

 

[Melb_shredder]

Tubes amps won't have a strain put on them during power down. So it's ok to turn it off like that . But as for your issue :S no clue man, sorry!

 

[::XeS::]

No clue here too Don't worry...fortunately the sound is still awesome