I just experienced my first NOS tube failure. One of the Siemens early 60s CCa tubes. The bad tube was installed in the center row of the line one, V2, right channel.
Here is what I experienced. When switching line inputs from the front panel I got a popping sound through the right speaker. Scared the hell out of me to say the least. Also up close I heard a slight fuzzy sound comming from the right speaker. I had pulled the CCa tubes earlier and installed a pair of early 60s Siemens E88CC I had just received. I listened to the E88CC tubes for about an hour and a half. I pulled the E88CC tubes and reinstalled the CCa tubes. I powered back up the Line one, when I pushed the line input for my CDp, thats when I heard the pop... Like a dummy, I pushed one of the other line input buttons to confirm what I had just heard...
I pulled the tubes one at a time and tested them. The bad CCa failed in section 1 of the dual triode tube. Section 2 still tested strong. The puzzling thing is section 1 does not show any shorts or grid emissions. I did not take a listen after the problem, I did not want to take any chances of damaging something.
This tube was from the last pair of CCa tubes I had just bought. I had maybe 150 hours on them.
I then reinstalled the early 60s Siemens CCa tubes that I had installed in the back row, and installed them in the center row. For the back row I installed the Siemems E88CC I had received today. Powered up the Line one, no pops when switching the line inputs system sounds fine.
Any thoughts? I handle the tubes like a new born baby. This is a first for me with an NOS tube.