Need help with ARC sp16 and tubes


I found the right channel out completely today for phono source only. Preamp is ARC sp16, 6 12AX7 tubes, 3 phono, 3 other. If I connect phono to a line level input, I get low volume sound in both channels which tells me its the phono section of the pre-amp, not cart or anything upstream.

I have spare 12AX7 tubes to test with one by one sometime soon when I get a chance.

My question is, is it common for 1 channel of a 12AX7 tube to go completely? There is sound in left channel but not sure if 100% or not at this point.

I have heard noise levels increase in the past with the ARC when tubes get weak and need to be replaced but have not experienced a 1 channel out scenario with it before.

Thanks in advance for any insights.
128x128mapman
Tobes, that's good to know.

My current tubes came from ARC about a year back. They shipped me 6 tubes, 1 special low noise (more expensive) for slot 1, which is the one most towards the rear of the three phono tubes to the right looking in from the front.

Knowing that now, I can be smarter moving forward about what tubes are needed to get the job done effectively without overpaying for no reason.

My phono section is very quiet. I have low tolerance for any background noise when listening. My only wish is that I could turn off the phono section separately from the rest to save tube life in that lately I have been lazy and listening mostly to music server digital.
I had never looked closely at the SP-16. I looked it up and I was suprised to see that it is very similar internally to my old SP-6b. Like a modern version of it. The SP-6b used 6 12AX7 tubes configured the same way. Based on that, my experience says that you would see a nice improvement with some NOS tubes.