Intermittent Humming/Buzz/Noise (solved)

[machew100]

Hi,

I have a crack with speedball upgrade, and I'm experiencing an almost vibration-like noise that happens pretty consistently, even when no audio cables are plugged in. The funny thing is that it only happens once the tube warms up and doesn't change with volume.

I've been fighting this for about a year it feels like. I'm fairly certain it's the big tube socket, as I have 1950s NOS tubes as well as two stock tubes from Bottlehead that I've cleaned time and time again with isopropyl alcohol, deoxit and now a nail-filing device to remove the black crud on the pins to no avail. I've cleaned the actual tube socket many many times with deoxit/isopropyl and pipe cleaners. I know it's not the small tube because the big tube is the only one that reacts when barely touched; the small tube reacts almost none.

For a majority of my time using the amp, the amp is dead silent for long stretches of time, then the noise swells up randomly and tapping the amp plate somewhat firmly with one finger made it stop, sometimes with an accompanying pop. Should I replace the tube socket? Because I've tube rolled so many times for the big tube socket and I can't get a consistently quiet amp, only a somewhat consistently quiet amp at best.

Should I replace the tube socket? What do these symptoms sound like to any of you? Sound like any one problem? If I need anything replaced I'm happy to get in contact with a Bottlehead rep and buy a tube socket or something.

Thanks for looking.

[Doc B.]

It could be a bad solder joint. Try reflowing all the connections on the octal socket terminals.

[machew100]

I'll try that this weekend if I can. If I wanted to test which joints were bad, I'd poke the wires beforehand with a pencil right? Do the tubes need to be in for me to hear if the cables would pop from poking, or can I leave the tubes out to test the joints for audio pops?

Also, if it's not that, would you say it's a bad tube socket? I was thinking maybe some of the tube gunk from my NOS tubes could've been forced in there or something.

[Strikkflypilot]

I think a wooden chopstick would be a better choice to avoid electricution

[Doc B.]

I would reflow all of the terminals on the socket first and see if that solves the problem. If it doesn't help we can come up with further things to investigate.

[machew100]

Thanks all, I'll post back here if I have any updates.

[machew100]

Reflowing the terminals was all that was needed, forgot to give a heads up about 2 weeks ago. Many months of mild frustration and that's all it took. Tsk tsk! 

[Doc B.]

I've been at this for over 20 years now. I still have absolutely no understanding of why builders often go into denial that they might just solve the problem in five minutes with a reflow. Just some strange quirk of human behavior.

[machew100]

I've been at this for over 20 years now. I still have absolutely no understanding of why builders often go into denial that they might just solve the problem in five minutes with a reflow. Just some strange quirk of human behavior.

Honestly, I had myself convinced that it was the tubes, because through coincidence alone it would *seem* like my pin cleaning made a difference for a short while. Thought if I kept at it enough I could fix it for good, but we know now that I was wrong and that reflowing was all I needed!

[Grainger49]

If this were video we could put it together where reflowing fixed the problems.  I saw a video of 12 times Bones told Captain Kirk, "He's dead, Jim."  This would be much the same.

Congratulations, now have a cold one and listen to some music.