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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.
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Showing 3 responses by mapman

mapman's avatar
mapman OP
21,835 posts
 
OK, problem solved. It was phono section tube slot 3 gone bad. Replaced that with a spare I have and back in business. Luckily it was not phono slot 1 which takes a more expensive very low noise tube in order to keep things quiet that is harder to replace.

The things we do for tubes....
mapman's avatar
mapman OP
21,835 posts
 
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.
mapman's avatar
mapman OP
21,835 posts
 
Tony,

Thanks for that. I'll keep it in mind.
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