Laney Lc30-112 problem.

[nici]

Hello.

I bought a LC30 a month ago. It's been in use approximately every day, but I haven't really cranked it that hard. However, I was on a two day studio session, and at the end of the second day the amp started to have a crackling and ringing sound. That is the sign of preamp tube failure, right? So I started to poke the tubes, but I couldn't find the bad one. I then bought a new tube (JJ ecc803) and started to swap it around, but it didn't help. In some sockets I would say the crackling and ringing got a little bit better, but it didn't disappear. The same sound comes when you poke the power tubes.
Should I change all the preamp tubes, or could it be the power tubes? Or is it maybe something else?

Here is a video of the sound it makes. This is with the stock tubes. Laney Lc30-112 Tube Problem?.mp4 - YouTube

Any advise is appreciated.

Thank you/ Nici

[Chuck H]

It's probably microphonic tubes. It could be a power tube (or tubes). If a preamp tube swap in all positions didn't help then I think it's time for new power tubes. It sounds like what I'm used to when EL84's go microphonic.