6550 vs KT88 vs KT90

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).

Great thread Jman-- and so CIVIL. Hi Trelja and Greysquirrel. As a (sometimes) tube amp wannabe, I'm afraid I have nothing to contribute-- except questions. I have a SF Line 2 pre-amp and have done a little tube rolling with it, and I'm considering a SF Power 2 amp (I'm not really set up for mono-blocs). Is the amp design or the tube type more important, re: the comment Greysquirrel made on amp design? I read the Stph review of the Power 2, but don't remember what tube type is standard, just that it is quite neutral as opposed to tubey, but I've assumed that this can be changed with a simple tube change? Any comments on the Power 2 and its tubes? I especially appreciate peoples assessments of bass quality of the various tube types because I have a big SS amp with excellent bass (McCormack DNA-2DX). Hope this post isn't stepping on your thread. Thanks. Craig.

I think they are both equally important. The most important aspect of a tube amp(in my experience) is the transformers. It is by far, the most expensive functional part of a tube amp. This is what separates Jolida from companies like Air Tight. Yeah, they both use the same tube type(EL34, and same tube once you retube the Jolida), but there is something that prevents you from attaining that same level of sound for the two. Transformers are as different as anything else in the amp. If we would allow that interconnects have a major effect on sound, then we also have to give transformers their due. They have several orders of magnitude more length than a 1 meter interconnect. Like most cables, most use different wire, and different construction. We also have to consider the circuit design, parts quality, etc.(things we NEVER mention with tube amps). That being said, we take tubes seriously because it is the one area of the amp we can control. Like different brands of gasoline yielding different performance in our cars(we can't change engines). We get different sounds from different tubes. Garfish, if you need to maintain the level of bass you are accustomed to, you need to look at amps with the larger tubes(6550/KT88/KT90). But, please go out and listen to an EL34 amp. There is a tube magic in many of them that is quite addictive. You may find yourself with two setups.