6550 vs KT88 vs KT90

I have tried all three tubes. (A)sevtlana 6550C, sev KT88 and the KT-90 type 3 from kevin deal. Iam have spent 9 months with the sev 6550c, 1 month with the kt-90 and 1 month with the sev KT88 on my Jadis Defy 7 amp. The overall winner, in my opion, the Sevtlana KT-88. 2nd place the sev 6550 and my lease favorate were the Ei kt-90 type 3. The last was a suprrise since it has alot of hipe. Evem thouth the kt-90 had great bass and a more lively upfront sound it was the least musicsal. The KT-88 has a lush and sweet midrange and high frequencys. The sev 6550c have great base also with more bottom end slam, although it lacks the clarity and sweet midrange of the kt-88. Both are excellent current production tubes. As for the kt-90's buyer be wear. Some may like it and some may not. It sure sounds different. The Sevalana tubes in general are more musical but none are perfect in every way. It's always tradeoffs but overall most I feel will really enjoy the new Sev KT-88. Good Luck, John

I love the treble and midrange of the EL-34 but find the bass unacceptably fat. I love the bass of the 6550C but not much more. Trelja, how does the bass and midrange of the KT-88 or KT-90 compare with the 6550C?

Notwithstanding the above comments, the sound of the tubes is dependent upon the amp. I had KT-90's in my prior amp (Jadis Defy7 Mk4) and now have Svet EL-34's in my Manley Designer Ref 250 mono's. The Manley's have simultaneously better bass (pitch, tightness, extension) and a more lush involving midrange and sweeter highs. I know the power specs are quite different (250++ w/ch for the Manley's and 100 w/ch for the Jadis), but they are similarly priced. I'm not an expert (in any way shape or form), but I do find this an interesting thread. BTW, is it possible to experiment with the 6550C's, KT90's, and KT88's on an EL-34 designed amp? Manley also has a Designer Ref 500 amp which uses 10 6550C's/ch vs. the Designer Ref 250's 10 EL-34's/ch. For what it helps, the Manley amps are "designed with high plate voltage/low plate current".

Great Thread. This is all very interesting to me having just bought my first tube amp, a Cary sli80. Ilove it, it's got 6550's, and I've been wondering whether to try some 88's. The first thing I decided to do was try different 6922's & 6SN7's. I wound up ordering some Tungsram 6922's and Raytheon 6SN7's. Looking forward to hearing a difference from my Sovtek & Chinese, at least I hope I hear a difference! The KT88's will be the next switch.

Krys, I found the KT90 to have the best bass of the three, far and away. Comparing the 6550 to the KT88, they are very close. I might say the 6550 to be a hair better, but that is probably only because of the KT88s sweet midrange. Drawing your ear to the mids(and possibly away from the bass just a bit).