I am using Ei(Yugo) KT90s currently. Please be advised there are 2 KT90s, the older version, and the newer(current) version(3rd generation). The two are NOT compatible. Also, beware the prices of KT90s are really high. The reason is the factory was bombed during the 1999 NATO campaign. I have heard no positive news regarding improvement in this situation. The KT90 is the largest non-triode ouput tube used in our hobby. It offers the most power and bass response of the three tubes discussed in this thread. However, there is also a negative to this, it will not physically fit into MANY amplifiers, as it is too tall. This is not an issue with exposed tube amps(such as Jolida, Jadis, etc.). The old version was criticized for being bright and harsh. The new(current) version does not engender the same response. I would submit that someone at all interested in 6550 tubes should use KT90, if possible. KT90 betters the 6550(A or C) in all areas. The KT90 also is a bit tubier in its midrange, yet offers an extended(the most of any tube?) treble. The 6550 is the least loved of the bunch, by many tube lovers. It is a good tube for a neutral(like Audio Research) sound. But that does not make for a cult following. If a sweeter tone is desired, at the expense of power and bass response, the KT88 should be tried. Both Svetlana and JJ(formerly Tesla and Teslovak) versions are excellent. The Svetlana brand are a little warmer. E34L is a higher output version of EL34 from JJ. Otis is correct about them. Use these if you are searching for the "classic" tube sound. Warm, euphonic, less control of the bass frequencies, etc. Svetalana EL34 are the warmest, followed by JJ EL34, then by JJ E34L. In general order from warm(and sweet) to neutral: EL34, E34L, KT88, KT90, 6550. In order of price: EL34, E34L, 6550, KT88, KT90. EL34 are half the cost of 6550. E34L a little more than EL34. KT88 cost a bit more than 6550. KT90 a good bit more expensive than KT88. Note: JJ E34L and KT88 tubes are available in clear(standard), red, or blue glass, so you can even use them as mood lighting. |
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). |
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. |
Thanks for the offer Eldragon! Ei tubes are available. In fact, Jadis informed me that they see no potential problems with supply. However, the sanctions will probably hurt us in the USA. No one will care because this is such a minuscule hobby. But, last year the price of a matched quad of KT90s was $96(in a Stereophile ad), within 2 months it went to $150. I am not sure where it is now, but buying from a high end dealer or Jadis will be over $500(as of February, 2000). I am just happy they supposedly last way longer than we usually expect tubes to last. |
Eldragon, I really love the Jadis. I have listened to many a product out there, and have EXTENSIVE experience with three in particular(Audio Research, Jolida, and Rogue). And, to me, the Jadis was a clear choice. I am somewhat surprised to hear the bass comments, because even when I had NO interest in buying a Jadis(late 80s - early 90s), the great bass(compared to other tube amps) was one of their main draws. I feel the bass is very good. Up there with any tube amp using 4 output tubes(can't compare to some of those BIG monsters using 16 or 32 tubes, obviously). And certainly, the best of ANY real world tube integrated. I believe it is a product of their massive transformers, large capacitance, and the KT90 tubes. It also has tone controls, so you CAN jack up the bass a bit, if ever needed. The amp is as detailed as I have been around. I hear things in music I have never heard before. CDs I have listened to hundreds(on various equipment) of times reveal new information. I am always amazed at cymbals, in particular. They are rendered with SUCH crispness, I always wonder why I haven't heard before. The detail may be a product of the passive preamp section. I like the combination of a passive preamp section into a tube integrated. The C - J CAV50 also does well using this combination. But, the Jadis is a MUCH better product. My main complaint with the C - J is its lack of power. Others complain about it being OVERLY warm, but I find that endearing of the C - J EL34 based amps. I imagine the Jadis could become quite warm with the Svetlana EL34s, if you are into that sound(I've yet to try). |
Rcprince, you may want to e-mail Jadis regarding the use of KT90 tubes in your amp. They go out of their way to recommend KT90, and to avoid KT88 with me. They say they have seen reliability problems with KT88s. I have never had this experience. Quite the contrary. And, while Frank Garbie is very helpful, his information is often at odds with what I get from Jadis directly. So, again, I would ask THEM about KT90s in your amp. They always give me a response within a day or two. Good luck! |
Tml12, I have EXTENSIVELY used both the stereo and monoblock Rogue amplifiers. Wonderful sound, but not what I call "classic tube" sound. The new tube sound(Rogue, Jadis, Audio Research) is much more neutral, powerful, and extended(solid state sounding, at least to me). What people mean when they say the best of ss and tube amps are converging. The amps sounded more to MY liking with the KT88s. A bit more sweet. But then, I like syrupy sweet tube amps(even though my Jadis is not). I know you will say this is crazy, but I always preferred the Jolida 302B over all the other Jolida integrateds, and the Rogue power amps. But, that goes back to my sweet sounding tube preference. In reality, the Rogues offer MUCH more: power, neutrality, bass AND treble extension, etc. All of the things that "the absolute sound" is supposed to sound like. Just trying to be honest in regards to my bias. |
Rcprince, I am happy you put the question to Jadis. As stated before, they really seem to love the KT90. They go out of their way to recommend it in their products. I think Frank Garbie is a great guy, and seems to offer a lot of help. I have however, gotten information from him that conflicts with what Jadis advertises or says. Particularly in tube substitution. He wasn't aware my Orchestra Reference or some other Jadis amps accept tubes other than what they came with. He has given me excellent help when I have gone to him. I know horror stories abound, but I have nothing but positive things to say. I am sorry but I can not offer anything in regards to old KT88s, as I have no experience with them. I apologize. Enjoy the tubes, Krys! |
