Standard Crack Channel Imbalance + Noise

[3ph00n]

I will try to follow the signal path from input to output and try to get some measurements using the 50 Hz tone. Maybe this could help?

[Paul Birkeland]

Now you can repeat this test with the amp running and no headphones connected.  See if your meter can read AC volts between ground and terminal 1, as well as ground and terminal 2.

[3ph00n]

Both readings are around .007 V

[Paul Birkeland]

Yeah, some meters won't measure AC in the presence of DC. 

If the pot isn't the balance issue, then it could either be a flaky solder joint or a tube that isn't well balanced.  Often times a tube that has a channel imbalance will remedy itself if you leave it running for a few days. 

[3ph00n]

Is it possible to check if the problem is the tube beside using it and waiting for the problem to fade away?
If it's the tube, does the warranty cover a replacement of the tubes?

[Paul Birkeland]

Is it possible to check if the problem is the tube beside using it and waiting for the problem to fade away?

This becomes a little difficult, as almost all of the tubes that we have had returned to us over the years quiet down after a day or two of use. 

If it's the tube, does the warranty cover a replacement of the tubes?

The warranty covers replacement of tubes that don't work properly. 

Depending on where you live, you may be able to borrow a 12AU7 or 6080 from a local tube seller (they are out there) to see if one or the other is causing your issue.

[3ph00n]

Sadly there are only onlineshops in my area... But a music store I know has a tube checker.
I will try checking the tubes there...

[3ph00n]

After some listening time the noise and channel imbalance is still there.
It wasn't 100+ hours of burn in time, maybe 30 to 40 but I didn't discover any changes.
The music store doesn't doesn't sell any 6080 or eguivalent tubes and therefore can't check them.

[3ph00n]

I got no other idea than changing the tube.
Is it possible to get a refund for the tube?

[Paul Birkeland]

We can exchange the tube, but do be aware that most of the "bad" tubes sent back work perfectly fine.  (We also test our tubes prior to shipping)

What part of the world do you live in?  Perhaps there's a fellow kit builder close by who can lend a hand.

[Doc B.]

Actually we only get a few tubes back. But PB is right, when they do come back they are most often just fine. If you want to send it back we can send a replacement.

[3ph00n]

I am from Germany so the shipping will probably cost more than buying a replacement tube here.

[Tom-s]

Where in Germany? I'm in Belgium/The Netherlands.

PM me for replacement tubes, try that first. If needed/possible i'm also willing to take a look at your Crack.

[Paul Birkeland]

I would also add that if you get a replacement tube and the problem appears to resolve itself, do go back and try the other tube again. 

There have been a few times where the act of replacing a tube will jostle a strange joint or a broken wire enough to get things working, which convinces the builder that there is just a tube problem, only to have the issue return in a few days.

[3ph00n]

I am from saxony which is quite far away from belgium...
Thanks for your help anyway!

I will see if I can get a replacement tube somewhere else.