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Tube Replacement Problem - Audio Research SP9 MKiii- V1 Tube Goes Dark w/ new V2 installed

Hi, Does anyone have any suggestions??

I’ve tried replacing the original Sovtek 6922 V2 position tube with a vintage NOS 6DJ8/6922 Amperex SQ circa 1969, but the original V1 position phono tube goes dark and I get no sound from my turntable. The new tube in V2 position works fine and sounds terrific despite the no phono with the darkened Sovtek in V1.

However, when I go back to the original 6922s in V1 and V2 position everything works fine and tubes light as normal. Do the new tubes need to replaced as a matched pair or is there anything else that I should know about replacing a single tube?

The unit is a factory SP9 MKIII.
33andthird

Showing 2 responses by oldhvymec

oldhvymec
5,101 posts
 
Soundslike half the tube is working. They are balanced valve right? I think in one position, where they work and  are wired to the side that works. In the position where it stops or goes black, just the opposite.. One half is working one half is not... That seems logical. confirm it with a tester or a schemo, ay.. either or...

Regards
oldhvymec
5,101 posts
 
You plug your original valves in and everything works.

You plug in a NOS valve and it quits working.

You have a bad connection (I'd doubt) or a bad NOS valve (I suspect)

Nothing needs to be soldered. Nothing is broke.

It never hurts to clean the pins, socket pins and or tighten them if needed. That's not the problem.

Think about what you said.. One valve works one doesn't.

Regards
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