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Spare valves?

Brian S

pfm Member
I am about to take possession of a new amp. It uses 4× KT90, 4×6922 and 2×6H30. I understand the amp. is self biasing. In the case of valve failure, is it OK to replace individual valves? Is it better to replace pairs? Please not quads! At this point I am only concerned in keeping the amp. on the road, not exploring alternative valve sets. All advice gratefully received.

BrianS
 
I would just swap the failed valve out and if you detect a change in the way your amp sounds then have the valves checked/measured out so you can match them where it matters.

I have an EAR 516 and for that I have a complete new set of output valves ready but I don't think I would swap all of them in if I just had one valve die on me. I would just replace with a used one I have. When I got it back from service with approximately matched valves (done by Tim d P) from EAR Yoshino, one of the output valves and two of the input valves had been crushed during shipping. I just swopped them out for some similar ones I had at hand. To me the sound is great, but perhaps I was just lucky?

This reminds me that I will have to have all my input and output valves measured and matched so I know which ones to pair. The EAR 516 has 8 valves in total in its dual mono circuit (4 x PFC802 + 4 x PL508). So I think I will have to match the valves in left and right pairs.
 


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