[Karkass]

thats almost 2 years now i purchased my bada ph-12 From pacific valve. Since a long time now im still earing a low but perceptible "hum" through my
AKG K701. The "humm" is constant and the volume do not affect the hum intensity. Im running now 2xGE GTA + 1xSylvania GT.

Here some solutions i tried with no issue :

-trying another outlet from my Belkin power console ,
-wall outlet
-changing my power cable ( Zu birth ) with a standard one
-changing tubes
-trying another headphone set ( old and cheap sennheiser ) still have the hum and stronger than my AKG
-trying second headphone output
-changing the location of the bada
-cleaning tube sockets
-cleaning tube pins
-changing RCA cable

lately i noticed the hum become intermittent when my computer is on , but the computer is connected on a different wall outlet . weird..

any advice !? Thanks !

 

[jonathanb715]

Grounding issues can be caused by connecting equipment via analog connections - what do you have hooked up to your system? Have you tried disconnecting one piece at a time? I was able to resolve my hum problems by not connecting my TV to my stereo.

JB

edit: this article is very helpful in figuring out noise issues with a system (and only tries to sell you their stuff a couple of times!): http://www.psaudio.com/ps/how-to/fin...nd-fixing-hum/

 

[analogbox]

AFAIK, low hums in tube amps are normal and they disappear once the music is on.

If the problem is constant and with high volume, you could have bad tubes or, as mentioned, it could also be grounding issue. Maybe, more experienced can help you with that.

 

[Karkass]

thanks for all those advice , and that link is intersting .

ok now i think this is not a ground problem , i done all possible tests . Even with a cheater plug , the hum still there and at the same intensity. I switched my NOS tubes for brand news EH GP, still no result.

Yes i do belive low hum can be normal and disappear when the music is on , but even in high volume , when in some recording the sound goes on one side that low hum show up in the other side.

once my wallet will permit it , i will probably bring it to my local repair store . looks like this is more than tube , ground or wiring problem .

 

[Golden Monkey]

Sounds weird, but have you tried turning your amp 90 degrees? If the noise being amplified is from your AC line, this will tell you. Do you have any sort of power conditioner you can put your stuff on, and isolate it from other stuff in your house? Everything you're describing (problem AND remedies tried) points to AC line noise, not faulty equipment or ground loops.

 

[Karkass]

I tried like you said turning the amp 90 degrees , even turning the amp on the top dosent affect the hum. I already tried 3 diferents AC line ,sadly with no result. Yes i have a power conditioner, a belkin pf60 pureAV . Isolating the amp from other stuf dosent do much .

thanks again for advices !

 

[tintin47]

Try buying a ground loop isolator from radioshack. Sometimes pieces of equipment can interfere with each other. If the isolator clears up the issue, there is a way to install a permanent ground loop solution on AMB audio's site, or you can just keep the isolator there.

 

[Karkass]

the hum show up even without analog stuff connected on the amp, but maybe headphone ground loop isolator can be an issue.

 

[takezo]

Quote:

Originally Posted by Karkass /img/forum/go_quote.gif the hum show up even without analog stuff connected on the amp, but maybe headphone ground loop isolator can be an issue.

or it may be a capacitor gone bad in the ripple filtering of the ac power supply..
or a bad resistor can cause humming and noise...
or even a solder joint gone dry...