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Tube issues, 12at7 affect KT88?

Hello. I have a McIntosh 275V. I just tube rolled my 12AT7's. Started listening, and one of my power tubes, a Penta Labs KT88 went bright cherry red. I shut it down quick, let it cool down and swapped back. Looks like it's back to normal. Letting it cool down again and I'll swap tubes again and see what happens.

If it goes cherry again, what would make the 12at7 affect the power tube like that?

Thanks in advance,

Tony
tonydec
tonydec OP
30 posts
 
Thanks. I had the tubes tested, and the one that was in the number 2 spot tested poorly, which I think corresponds with the number 2 KT88. I did plan on replacing it because I figured it severly shortened it's life. I'm going to have them all tested just for curiosity to see the differences in numbers.

Tony
jedinite24's avatar
jedinite24
1,503 posts
 
Hi Tonydec

What was the outcome of your checks? Were the KT88s damaged by the faulty 12AT7 tube?

Thanks
tonydec OP
30 posts
 

Sorry, but I dropped the ball on this for sure.  To update, I stopped using all the Telefunkin tubes.  They all tested very low.  I tested the KT-88's, and all tested within a couple of numbers of each other and still in strong range, but I replaced the one that ran red in an abundance of caution.  I can't remember the specific numbers, it has been 13 years after all.  I will add the KT-88's are still being used, so no long-term damage had occurred to any of the other tubes or the amp itself.

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