Tubes for Conrad Johnson Premier 11a ????

The most popular here has been the Ei KT90 Type III. Assuming they are burned in properly, they will last forever...I mean I have never replaced a pair that ran low on emmissions.

But if you use the Svet 6550C or KT88 you will be doing just fine.

I tried KT88's in my CJ 12's. This is the first time I've seen a situation where I did not flat out prefer KT88 over 6550. The KT88 had a bit more power and more full sounding, but the CJ is already by nature full and sweet sounding. I think the 6550 had a bit more detail and nuance at least in my setup. It boils down to what are your other components and your personal taste. If I had very neutral speakers (e.g. Thiel) the KT88 would probably have been a revelation but my Spendors are already warm sounding, and so the 6550 proved to be a better match IMO.

Trying KT88 in the CJ is fun and whether or not you end up keeping them I don't think you'll regret trying it out.

Art

ps: CJ does not suggest using KT88 in the amp. I've spoken with them about it and they just seem to prefer the sound of 6550's with their gear. They don't indicate that KT88 would damage the amp, just that they have not optimized the amp for it.

I have been using Sed KT88's in my 12's.and i prefer the the better bass,and warmer sound.I just purchased some Golden Lion KT88s so far they seem to sound a bit more vibrant.Need more time to listen.

I know this isn't to point but I thought I'd offer this experience: I changed the small tubes to NOS RCA's with what I considered to be quite dramatic effect. I won't try to detail the change but there was significant across the board improvement.

My experience in speaking with CJ about using KT88's instead of 6550's was similar to Art's. I never tried the KT88's because CJ said that I would not be able to bias them in my amp.