2. amps-preamps
  3. 185613-78903

Tube arch

Ok I’ll keep this short. So my last post was about a tube arc. Took out a resistor on one of my Audio Research Ref 750s. I replaced the resistor and put in a matching KT150. My question is how can I avoid this from happening again. Someone said that when the tubes get up there in hours there is a very good chance of an arc will happen again. After a certain amount of hours should I just change all the 18 KT150s ? Even if they still sound good ? Btw. I have always had SS amps and pre amps. I finally bought an Audio Research REF 6 pre a few years ago and had it upgraded to the 6SE. But as far as tubes amps the Audio Research REF 750s are my first tube amps. This will always be on my mind now especially when the hours of the tubes start reaching a high hour number. Thank you. Mike. Ps I heard that this was a pretty rare thing to have happened and it was probably caused by shipping.

tattooedtrackman

Showing 1 response by lem321

lem321
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tubegb

In general Audio Research recommends changing/replacing output tubes in their amplifiers every 2000 hours. Assuming you have the owner’s manual, you should be able to confirm same. Another suggestion would be to periodically check the individual output tube bias.

Audio Research recommends changing tubes every 2000 hours in their amplifiers that use KT120s and 6550WE (Ref 250 and Ref 75). With the newer amps (250SE, 75SE, 160M, 160S) running KT150s, the manual now recommends changing the KT150 every 3000 hours. The 2000 hour recommendation however still holds for the 250SE and 75SE that still have 6550WEs. The newer 160 series amps now have auto-biasing.

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