Static/noise in right channel.

[Rhok]

Hello guys,

I have had this issue on and off with my amplifier. Sometimes it sounds like a piece of paper flapping in strong wind, and other times, just a common white-noise electronic buzz. This occurs when disconnecting the device from my source, so that's not part of the issue.

I have purchased additional 12AU7A tubes to see if the problem still persisted, and it does (I'm pretty sure its relevant to the 9-pin area) for one odd reason. If I put pressure on the tube in a pinching motion (little to no pressure, just making contact with the sides of the tube with my finger) the static stops. I've checked all of my solder points for cold solder joints, and redid all of them just to knock it out of the way before posting this, and the issue still persists.

I've tried moving my amplifier away from any other electronic devices (4-5 feet away from anything) and it still occurs, I have no idea where to begin troubleshooting this or enough knowledge as to what may cause such a thing.

Any assistance/guidance would be much appreciated.

[Paul Birkeland]

Your assertion that this is a flaky solder joint is likely quite correct.  It's possible that it may also be on the octal socket.  A good reheating of all the joints in the amplifier should be helpful.  (It could also be a cold joint on the volume pot)

[Rhok]

Well, prepare to face palm. I went about reheating all of the joints, plugged it on, got tube glow from both tubes plugged in my headphones and heard no static. Unfortunately it's because somehow I had broken the path towards the headphone jack.

Anyways, it looks like the LEDs are no longer receiving power on the 9pin, I looked over everything I touched up even though obviously there is something loose/making a poor connection now I couldn't see it.

If someone could direct me to what terminals require appropriate connection for the LEDs to glow we should be in good shape.

[Paul Birkeland]

A voltage check will provide some reasonable indication of where to look. 

[Rhok]

I was actually able to identify what broke the circuit and solved that issue, however after going over all of the terminal reheating every joint, paying special care to the 9 pin terminals, and pot terminals, the noise in the right channel is still present.

Additional information: The noise occurs a few seconds after the tubes get warm, but does not disappear with time. I have left it on for hours without use just to see if it would disappear.

Anymore ideas for me to try? - Also I do have a composite 270k resistor instead of a metal film one if that could possibly create this issue.

[Paul Birkeland]

Is it still the case that rocking the 12AU7 tube eliminates the noise?

If you have music playing while you do this, does rocking the tube also cause the music to cut out at the same time?