The Sound of Electricity in the Left Channel Only

[williaty]

OK, so my Crack+Speedball has been making a tiny amount of noise in the left channel only for a while now. It hasn't had me too worried because it's very low level and it goes away if you unplug the headphones and plug them back in. I've been trying to figure out for weeks what it sounds like so I can write about it to you guys. I was going through descriptions like static from an analog modem, voices on an amplitude-modulated carrier that you were just a bit too far off frequency to actually recognize as voices, etc.

Tonight, I recognized it. It's the sound of an electric arc. More specifically, it reminds me of a Jacob's Ladder. Sort of an irregular bbbbbzzzzzZZZAP! repeating again and again. The sound from the Crack isn't constant, isn't rhythmic, and varies in length and period. However, it sounds a whole lot like this:

Any idea where to start troubleshooting this one?

[Grainger49]

I had a noise like that but it was caused by an old refrigerator.  It was not on the same breaker as my system but the outlet that the refrigerator was plugged in was 2 feet from the outlet that my system was plugged into.  Probably just the proximity of the refrigerator itself.

You eliminate outside sources by taking the source and Crack to a different room and trying it.  Easy, but might not work.

Now for that Jacob's ladder, watch out for the ozone, it will give you a headache (just kidding, I read your post better than that).

[Doc B.]

Yes, it could be interference from an appliance kicking in coming over the power line. Or it could be a tube that is getting noisy. There's a slight chance it's a bad cap. But if you are using the stock caps, unless they have been damaged inadvertently it is not too likely. It's also worth looking over the solder joints, particularly those on the PC boards, to see if there is a pad that is only partially soldered or maybe has excessive flux mixed in with the solder.

[Laudanum]

With it only being the left channel I would think that it wouldnt be likely that an appliance or some other noise coming in over the AC line is the culprit.  Grainger and Doc are much more tech savvy than I am so I think they missed the left channel only part.  Or, Im just dumber than I think I am :-)
Easiest thing is to rule out the tubes first by swapping in some spares.  You can definitely have noise in one channel from a bad tube.  Then maybe check solder joints, focusing on that channel.  As usual, I could be off but seems like the most logical things to check for starters. 

[Paul Joppa]

If unplugging and replugging the 'phones solves it, then it may well be in the jack or (more likely) in the solder connections to the jack. A shot of contact cleaner to the jack and/or the ohone plug is in order if the solder joints don't fix it. (Try another set of phones if you have them - could be the headphone cable, too).

[Grainger49]

Desmond is right, I wasn't thinking about the one channel aspect.  Paul is spot on, the headset jack is most likely.  It could be the headset plug or wiring.  It will take a little investigation but you should have it located soon.