The first tube (closest to the front)is the 12AU7 and the second is the 12AX7.
10 responses Add your response
Thanks for your help. I have been struggling with trying to figure this out for the last few days as the previous owner does not have the manual either and cannot remember the tubes.
I just got some Telefunken tubes that I would like to try out.
Another quick question, currently the amps are fitted with KT90 Ei tubes which sounds very good to me. However, the tubes are also getting old and have some microphonic noises so I think about replacing that as well. Currently it look liked KT90 Ei is not easy to locate however, I am trying to negotiate for some Gold Aero KT99 which if works out, should be great. However, if that does not happen, the only KT90 readily available is KT90 EH which I heard some good and some not so good thing about. So I am thinking that may be KT88 might be a way to go. What's your opinion on this and if I should go with KT88, any particular brand?
I heard Jadis Defy II with 6550 and much prefer the midrange and treble of JA200 with KT90. I am not sure how much of it is the amp and how much of it is the tubes.
Unfortunately with needing to buy 20 tubes at a time, experimenting on my own is not a very economical way of going about it :(
Thanks for your help.
Depending on the speakers you're driving makes a great deal of difference on the tubes you will like(at least it does for me). I used SED EL34s for years on a Cabasse set up. I loved the rich, liquid, sound. When I bought an old pair of Hales Concept 5s I put in an old set of Sovtec 6550s that I never liked with the Cabasse. The extra punch and leaner midrange(not a bad lean but needed to get more realistic midrange)that the 6550s gave me was needed. I also have a Defy 7 KT90 and it can't compare in any way with the 200s. One other thing to think about is the tubes last for about a year to a year and half. Another reason that I liked the EL34s. They are cheap. Enjoy.
Thanks for all the inputs so far.
I am using the JA200s with Usher BE20.
As far as KT88 go, in my price range that I can find so far, there are Genalex Gold Lion, JJ/Tesla, Sino KT88-98, SED SVKT88, SED Winged-C or Jadis Labeled KT88. Any comments on these various tubes for use with JA200s would be much appreciated.
As far as using KT90 Ei, I really like the clarity, extension of the treble and tight, well controlled bass and none of the warm and fuzzy bass like some 6550 that I heard. However, I could use a little more warmth and body to the mid range especially in the vocal part. I also listen to lots of solo classical piano repertoire, opera, orchestral music, lieder etc.
Thanks for your help.
Though I have no experience with a JA200, my path down the road of other Jadis amplifiers has led me to the following opinions:
1) KT90 are a poor tube choice. The KT90 is a cold, sterile tube, which does not allow the magic of a Jadis to come through almost at all. Why did the company choose this tube? Well, they preferred the Tesla/Teslovak/JJ KT88 of the mid - late 90s, but the reliability of those tubes was such an issue that job number one is not to have the amplifier go down in the field
2) 6550 are not as good as KT88 tubes. Again, the KT88, in general, is a more romantic, emotional tube. You buy a Jadis to produce the romance and emotion of live music. It doesn't make much sense to use a tube which does not allow that
3) KT88 are a very good overall choice. The tube has a nice fat mid/upper bass that I like, with the sweetest presentation of the larger tubes.
4) EL34 are my favorite output tubes, with a midrange that is simply and startingly beautiful. The downside is that you are going to give up bottom end, to the point where it may be unacceptable. Eventually, through trial and error, I've found the key to resolving this is to find the right 12AX7 driver tubes. You can even produce thunderous bass by getting this right.
As an aside, the JJ K77 strikes an interesting balance between the EL34 and KT88. Its midrange is nowhere near as magical as the KT88, but it does trump most KT88 I have tried. And, the low frequencies seem to be as powerful as the KT88 in most regards, though they can be a bit bloated if other things aren't taken care of.
In conclusion, my choice for a Jadis is the EL34. However, if I didn't pick the right driver to account for the lack of bass, I'd go with a JJ KT77 (first) or one of the KT88 variants (secondly).
Thank you for all your help. This has been very helpful and lots of information to think about.
Trelja, on Jadis site, only KT88 KT90 and 6550 are listed for JA200. I understand that EL34 and KT77 are quite similar but not sure if they would work in this case.
Also, where is a good place to buy from? I looked up a few places, tubedepot.com, tubestore.com, thecableco.com, vintage tube service, upscaleaudio etc. I only dealt with thecableco.com in the past and have been happy with their service but never bought any tube from them. Non of the local store here stock what I need in adequate number so mailorder seems to be the only way.Upscaleaudio seems to have a lot of praise around here but a bit difficult for international order.
You should check to see just how old your Jadis amps are and whether the transformers in them are the originals (optimized for the KT88/6550 or EL34 types) or the newer ones, which may have been optimized for the KT90s. While all of these types may work with either transformer, you might be missing the last word in performance from the amps.
Trelja's descriptions of the sound with the tube types mirror my experience using the similar but less powerful JA80s. My favorites in the JA80s for the music I listened to (a lot of classical and large-scale symphonic) were the original NOS KT88s--6550s were sort of a brute force tube, lacking the beauty and finesse of the KT88s and EL34s, and EL34s just weren't up to driving my speakers in the deep bass.
I will point out that it does not pay to cheap out on tubes for these amplifiers. Every tube that I used in the amps other than the Genelex KT88s would start going bad within a year, while the Gold Lions were still going strong after 4 years. The best person for tubes in my experience is Andy Bouwman of Vintage Tube Services; his prices are not cheap, but with him you know that you are getting what you pay for (and there are a lot of fake tubes out there). I would be cautious with the new Genalex reissues, as I do not believe that they are as well made as the originals.
You have purchased a classic pair of amps with a distinct sound, I hope that you enjoy them as much as I enjoyed my JA80s.