Loud pop/crack when tapping front end of chassis plate [solved]

[crackaddict]

Hi all,

I've been using my Crack with no problems for 6 months. It was a clean job, all joints nicely soldered (I think), and all excess wires cut off. All was good. I received a second Crack kit and decided to do an A/B comparison between my burned-in tubes and the new tubes I got. The 6060 tube was actually faulty, in that it had a loose rattle in the base. I plugged it in anyway, and as I powered up, there was a pop and a spark in the tube. I immediately shut down and just went back to the original tubes.

Now I have a new situation. With the old tubes, as well as with a replacement set of tubes I got, there's a loud cracking sound in the headphones when I tap the metal plate, the volume knob, etc, even with the volume turned all the way down. Tapping near the power supply end doesn't do this, and it's more sensitive as I get closer to the smaller tube. It's quite loud and I'm nervous about it damaging my headphones (and ultimately my hearing).

Any help would be greatly appreciated!
Derek

[Doc B.]

90% likelihood you missed a solder joint.

[Nathan]

I'll concur. After I first built my crack I was also getting a cracklings noise. So I decided to reflow solder joints. I couldn't get at all of the but I found one joint to the 12au7 unsoldered. Mission accomplished-

[crackaddict]

Brilliant! Turns out the one wire which passes through one side of the volume knob to the other was not solidly soldered where it passes through. No wonder it was happening when I tapped the volume knob. Wonder why it didn't show up earlier, but nonetheless very happy that it's all sorted!

Thanks all for the quick replies. Great forum!

Derek