Preamp issue?


My Cary Slp3 started to​ act up.
Few days ago I noticed something was off, but didn't have the time to listen critically..... yesterday it was even more pronounced but still not obvious...I realized that right channel is a tiny bit lower level than the left channel.
I eliminated all obvious issues, like bad connections, balance knob turned, etc...
I don't have spare tubes, and before I start opening the chassis and switching the tubes, just want to make sure this is even a possibility.

Thanks

ether
Ether,

I'm glad you found the problem,you can't use the 6h30 in place of the 12au7's.

The 6h30 need to be used in a circuit designed for them,don't try it.

Best of luck to you,

Kenny.
I've had tubes on one channel lose gain or volume before but they usually get noisy and grainy in the sound first.
Please don't put the 6h30 in your preamp!  There are plenty of NOS and new 12au7 options you can try and they are quite cheap.  You can do a lot better than EH.