Tube amp down, need guidance from the experienced


I listened to my McIntosh MC275 Mk.IV all day yesterday without issues, as usual. Today I turned it on and left the room. Didn't pay attention at startup. Ten minutes later I realized it was not on. Eventually I figured the fuse had been blown, and replaced it. Turned it on again and found one KT88 was not glowing and cold. The rest of the tubes, both small signal tubes and KT88, were all on. Didn't attempt to play anything, turned it off, and here I am.

Obviously I need to replace the KT88, preferrably all of them. Unfortunately I don't have any spares on hand. What I'm anxious about, though, is to figure out if anything else was damaged. Is there reason to believe something else might have been damaged when this tube went off? First time a tube fails for me, and have seen a number of horror stories told on the net.

Thanks much!
lewinskih01

Showing 2 responses by newbee

Small tubes can last 5000 or more hours. I replace mine when the sound becomes dull or noisy. I keep extras about so when I question the effects of age I simply substitute in a new tube(s) and see if there is a meaningful improvement.
Before you decide which tube to use, consider it's reputation, in general, for the tone it will produce (with your equipment - it is about synergy). I think the Gold Lion Genelex is an excellent place to start if you really don't want/need something specific in a tube, that is a tonal color to match your speakers and the rest of your stuff.

FWIW I've never used your Mac. I assume that it can use other tubes in the 6550/KT88/KT90 (and maybe KT120) family of tubes. If that is so, you have a lot of tubes to consider which can help you achieve a tone to match your system.