Jadis amps and pre-amps still competitive?

This is what it says in Jadis' website:

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2- POWER PENTODES

KT90 : With its plate and screen dissipation of 60W, the KT90 is the most reliable tube that we know of. This is why our JA 800 amplifier uses this tube exclusively. The KT90 will also be supplied as the standard choice in the new JADIS range (JA 50, JA 100, JA 250)

6550C : The most widely used power tube. We use Russian tubes produced in St. Petersburg .

6CA7 With a sweeter sound than the KT90 or the 6550, this tube can be used on a large variety of amplifiers.

KT88 : This is the reference tube for audiophiles. We use tubes specialy built for us

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http://www.jadis-electronics.com/pages_eng/info/tubes.htm

Are the KT88 tubes that most of the Jadis amps seem to be using these days, JJ KT88?

In my own Jadis, the KT90 were stock. But, now I see that they come with KT88. I believe the reason is the lack of KT90 availability after the Ei factory was destroyed by NATO. However, now ElectroHarmonix is producing KT90 tubes, though I have heard they are not quite as good sounding as the Ei.

I agree with the statement regarding KT90 reliability. Mine ran for 5 years with a lot of play. One shorted, with no damage to the amp, and the other three tested good enough to still probably be OK for a while. The sound was quite neutral with this tube, with excellent power, and even balance across the frequency range. Extension at both ends of the spectrum, but particularly bass, was outstanding. Overall, however, I found myself wanting for a more romantic, tubey sound.

I retubed the amp with JJ E34L tubes. Power was down a fair amount, as well as bass response. However, the tone of this tube was just about perfect through the midrange. The sound of each note and vocals was as good as I have ever encountered. Treble was also very nice. I only got to put about 10 hours on these tubes, but my impressions were immensely positive. I have sold the amp to Springbok10, and he seems to love it. He has told me that the sound has improved tremendously now that the tubes have 150 hours plus on them. Highly recommended.

For a short while, to compare to the JJ E34L tubes, I tried JJ KT88s. Wow! My complaints about power and bass response were more than addressed, while the spectacular sound of the midrange was still there. I will say that this tube seems to have a midbass fatness that while I find intoxicating, could be argued that it might not be completely accurate. Absolute bass extension was still not as much as the Ei KT90, however.

I think overall, I would either go with JJ E34L or KT88 tubes. I would love to hear the amp with the E34Ls with 250 hours on them. The midrange and treble should be about as good as it gets. Still, presuming the KT88 is close in this regard, I would probably opt for that tube.

Fernando, that adjustment might be the same thing I was referring to in one of my above posts. Hopefully, Pierre Gabriel will speak to the biasing of the DA5 and DA8.

Treja, I have a Defy7 MKIV and would like to try the JJKT88's, doees the "JJ" refer to the brand of the tube? Or is it part of the designation of the tube, as I never heard of "JJ". Can you please clearify. Thanks.

I think Joe's talking about the brand, JJ Tesla.

Thanks Reprince.