Ringing in right channel with overtones

[Nignoog]

When i turn my crack + speedball on a faint but constant ringing occurs in the right channel. It is unaffected by volume. Sometimes it cycles up through an overtone series. It might be psychosomatic, but it feels like it creates pressure in my right ear. With music on it’s not so bad, but when things are silent, it’s very obnoxious. Wondering how best to troubleshoot it.

[Paul Birkeland]

Frequently an issue like this can be caused by pollution from nearby electronic devices, especially those with wireless capabilities.

[Nignoog]

Thanks for your prompt response Paul. I live in an apartment in Manhattan so there are A LOT of wireless devices around. Two follow up questions:

1. I feel like I did not have this problem until recently. Are there any other causes I could try to rule out besides wireless frequency interference? I will try plugging it in at different outlets and see if that ameliorates the problem.

2. Why would it only affect one channel and not both?

[Doc B.]

Try cleaning the tube pins. Dirty pins can make tubes oscillate sometimes.

[Nignoog]

I will give that a shot. Will Hosa Deoxit contact spray do the trick?

What causes the oxidation? I live in NYC so it’s been very humid. Anything I can do to prevent this in the future?

[Nignoog]

I plugged the amp into my an outlet in my bedroom and bathroom but the ringing continued in different spaces. And I cleaned the pins on both tubes but there is still a persistent ringing in the right channel. Any other ideas?

[Paul Birkeland]

Have you tried turning off your phone?

[Nignoog]

Yes. I am almost positive it is not the phone. I experimented with moving my phone and wireless mouse closer to the amp. The interference they cause is a rhytmic buzzing or clicking sound. Moving closer or further from the wifi router also didn’t yield any change in the sound.

Here are some other observations I have made in trying to troubleshoot it:
1. Switching L and R channel chord on my HD650s. As expected, ringing continued in L channel instead of the R.
2. I plugged my HD598 into the amp and cannot seem to hear ringing, but when I plug the HD650s into another amp there is no ringing in the 650s. Could impedence exacerbate the problem?
3. When I was cleaning the 6080 tube, I could hear something clinking inside the tube. I could not see what was loose but something was moving in there.
4. This could be psychosomatic, but when I turn the amp off for second and then switch it back on, the ringing disappears and then slowly reemerges.
5. I tried yelling at the amp and scolding it, but that had no effect either.

[Paul Birkeland]

There could also be something riding on the AC lines in your wall that's coming through the amp.  For the sake of eliminating that possibility, it's always nice to try the amp at a friend's house or your place of employment. 

I've also tried yelling at my projects when they aren't working, but I haven't figured out anything effective yet.

[Nignoog]

EUREKA! I have discovered the culprit. Before I moved the amp to another location I decided to check the power cord. I gave it a jiggle where it connects to the amp because it never seems to sit flush and the ringing stopped! Based on it's alignment, weird sounds are produced from ringing to a breathy popping sound. Now the question is, is the issue with the cord itself or with soldered parts beneath it?

[Paul Birkeland]

You could always try a different cord.

[Nignoog]

I tried a different power cord and it made no difference. I tried plugging it in on another socket outside of my apartment which also made no difference. I reflowed the solder joints around where the power cable is plugged in. This made a huge difference, but there is still a humming/ringing sound that fades in and out. It is much fainter now. Could a bad solder joint be the cause? Is there any area I should focus on or should I consider doing some more reflowing around the power unit?

[Paul Birkeland]

You could post some build photos, maybe we can see something that could be the cause.

[Nignoog]

I uploaded a few pictures per your request:

https://imgur.com/a/yJO2elo

In the meantime here is what I have done:
1. Reflowed almost every joint around the power supply and power tube.
2. Removed and filed the pins on both tubes in case there was any oxidation.
3. Tapped everything with a chopstick.

It seems like there is nothing I can do to stop, initiate or change the ringing/hum/whine that occurs in the right channel. It is still very soft but it's irritating and over extended periods can be a little painful.

I also changed my search query in the forum from "crack ringing" to "crack whine" and found a lot of people with similar complaints who solved their issue by cleaning their pins or getting new tubes. Based on my observations about there being something rattling in my power tube, a whine in the right channel and a slight channel imbalance in the right channel, I am beginning to suspect one or both tubes may not be functioning properly. Additionally the overtone series starts as the tubes are warming up. It reaches a constant pitch once fully heated which further leads me to believe it is tube related.

NB When I lean in very close and put my ear next to the power tube I can hear a ringing/whine.

[Paul Birkeland]

Is this noise present with the volume pot turned all the way down? 

If you can snag a 1uf/250+V capacitor from your local electronics surplus shop and a pair of clip leads, we can isolate where the noise is entering.