Best kt88 for VAC Avatar Super

VACMAN, I don't believe I have tried the Svetlana winged C.

Maineiac,

After reading your enthusiastic post, I ordered a matched quad of Gold Lions from Tube Depot (on sale for $109 for a matched pair). They will be going into my VAC Phi 200 amp.

Questions for you or anyone with opinion and experience:

1. How long did it take them to burn in?
2. Did you keep your VAC powered on 24/7 during the initial burn-in?
3. I read the RAM Tubeaudiostore.com site, which has them on sale for $75 each, but tubes are matched by a proprietary computer program. Anyone with experience with this, is it worth the added cost?

I buy my tubes from Jim McShane, he is great to deal with and provides top notch service. I just received a back-up quad as the set I am running now have been at it for over 1 year in my amp. I think you will find that they will work pretty well out of the box and it won't take too long for them to settle in (30-40 hours). I would never leave my amp on 24/7 for burn-in and always turn mine off if I am not going to be listening to music in the next hour. I was talking to a dealer the other day who told me about a customer who blew up a set of new tubes in a VAC amp because he didn't properly mute the unit when he was getting initial bias set. With new tubes I always start at lowest bias setting and let tubes warm up for 10-15 minutes before bringing up the right voltage.

Thanks Maineiac, I'll report back once the Gold Lions settle in.

FWIW, nobody really NEEDS a matched quad ;--) Push-pull amps (the most common) work in matched pairs. However, if your amp takes four of something, or eight of something, then there are certain economic and operational advantages to buying FIVE matched tubes (for each group of four):
1.) You don't have to keep the matched pairs separated. You can plug any tube into any of the four sockets and still be running two matched pairs.
2.) If you buy FIVE matched tubes, then should one fail, the fifth (spare) can replace any one of the four that fails. If you're particularly O/C, you can even rotate the five (like tires) so thay all have the same 'wear'. (This may sound silly, but tubes, especially power tubes, DO change their test readings over time, even though they are still performing just as when new.)

To the question of breaking tubes in 24/7: I don't recommend it. It won't harm the tubes, and back when there were ONLY tubes, a lot of gear was left on 24/7, sometimes for years, for various reasons, with no ill effect. But with NEW tubes, it's best if you are present, with your hand near the on/off switch if fireworks should start -- which they most often will in the beginning -- usually right after turn-on, or as the tubes are warming up. With a few exceptions, most power tubes are substantially 'broken-in' (and can be pronounced 'reliable') after 25 -- 50 hours. That's only a dozen listening sessions at most. And with a lot of power tubes, you won't actually want to 'listen' for the first 25 hours anyway ;--)
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