Sovtek 6550 - Can they really be THIS bad???

Sorry to hear about your DA60 - if the seller knew that the amp had been modified - and how could they not unless they too bought it used?? - he/she certainly should have revealed this. Hope your Jadis expert can get it back to "stock" performance for you.

Holly

I own a pair of CJ premier8s, used them for a year with Sovtek (16 of them!) tubes with no problems except wear. I changed to Svetlana C about 6 months ago and sonic improvements were not subtle.

Now, I have a friend with a Jadis amp (Defy7 in this case) and he got the best sound from it testing and measuting all tubes and install them in sets of 4 at the clostest measuring rate, since the Jadis amp works (I understand) in quads (serial) and does not have the autobias feature of my CJ.

Hope this helps.

Fernando

I have been in contact with both Pierre Gabriel - North American distributor, and Avi Brand - US service rep, along with the former owner in regards to the amplifier.

In Avi's estimation, he knew this particular amplifier, and the person who modified it. Without naming any names, he was pretty sure the amplifier had major problems ala the mods this gentleman normally performs. I had already found two of the fuses in adjacent tubes to be blown. I took it up to him on Long Island, and he found a considerable amount of things, apart from the mods wrong with it. In less than a week, he let me know it had been restored, and though I should change out the tubes for something better sounding, it was now something that he predicted would make me happy.

I'm more than a bit unhappy with the former owner selling me the amplifier as it was, considering the excellent condition, especially mechanically and sonically, he listed it in, told me over the phone, and also when we met to give me the amplifier. Not sure what my recourse with him is yet...

Yesterday, my daughter and I again drove up to Long Island, and picked up the amp. Avi and I spoke for a while, and he felt confident I would feel I now had a Jadis. Obviously, the horror stories in terms of astronomical waiting periods in Jadis repairs are nothing of an issue when it comes to Avi Brand. He even called late last night to find out how I liked the sound, and to make sure that everything was working properly. More than gets my recommendation for sure.

In listening last night, what a difference!!! Avi was right, it was again a Jadis. With those herculean transformers and 8 tubes per side, it should make some power, and it does. Far in excess of the DA30 and JOR, though in a very relaxed way. It plays as loud as desired, and never falls apart (interesting, in another thread, someone mentioned a Jadis DA60 integrated falling apart during the music - NOT!). It was VERY good sounding now.

As good as the amp sounded, I put my quad of JJ E34L in one channel, and with the balance to that channel, was able to A/B the sonics of the Sovtek 6550 and the JJs. NO COMPARISON. The JJ Blue Glass E34L tubes are simply night and day better sounding. The difference in power (in terms of loudness), as I have also seen in the DA30, was trivial, though the bigger tube's bass is better. Of course, the dynamics and life of listening to one channel is not very strong. Still, the improvement was more than obvious to my wife and I.

Sometime in the next day or two, I will hook the amp up with the Coincidents. Which are the speakers I bought the amp for in the first place. I've found no amp to be better for the Coincidents than my JOR and DA30, so hopefully, this will be the top of the mountain for us and a lifetime purchase.

So, the Sovtek 6550 is not a tube I recommend for anyone. Hard, edgy, irritable. It's just a bad sounding tube compared to what else is in the marketplace. In terms of 6550, the Electro Harmonix are far, far superior, as are the true Svetlana/SED KT88. My dilemna is whether to now retube the DA60 with JJ KT88 or E34L. The KT88 will do the bass better, these E34L seem to be, as in my JOR, potentially glorious in the midrange. Will have to think about it a while...

Lastly, I'd like to say that for anyone considering the purchase of a Jadis, you are FINALLY once again, in good hands. This week, Pierre has offered to upgrade the amplifier for me to current specifications, for the price of shipping only. He wants me to have all of the recent modifications, and a unit sounding as good as a DA60 possibly can. He'll even send me the box to ship the amplifier in. I would have saved the repair bill had we had been able to reach each other through the phone tag over the holidays, but still, you really have to take your hat off to Pierre. I feel that there is now tremendous incentive for audiophiles to return to the Jadis family. The sonics are so good that they will surprise many an audiophile who has become used to the what the rest of the companies have been selling them over the recent past, and the support from both Pierre and Avi is second to none.

how did your jadis orch ref. sound with kt 90's if i may digress?

Jonah, the Ei KT90s had been standard issue with the Jadis products for a long time. I was speaking to Pierre Gabriel prior to HE2006, and he felt my assertion that a few notorious batches of mid - 1990s Teslovak (now JJ) KT88 was enough to have Jadis switch to the tremendously rugged Ei KT90 was probably accurate.

That being said, both of us are far more enamored with the sound of the JJ KT88, which Jadis is currently using.

Next to some of the 6550 variants, the KT90 is probably the most balanced tube from top to bottom, sonically. Bass extension is deep and taught, and the treble is nicely extended. However, the soul of music is in the midrange, and this tube lends a coldness to this area that really left me wanting in comparison to some of the other tubes I have tried.

In case you are wondering, I've now been blissfully enjoying the Jadis DA60 for several months now. Currently, the newly released JJ KT77 tubes are in the amplifier, as I like what they do overall. Powerful low frequencies, like the bigger tubes, along with better mids than the larger tubes offer. The most glorious sound comes from the JJ E34L, but the bass is pretty weak with this tube. Still, I'm going to be picking up another quad of the E34L (to make 8) very soon to tide me over when I want that incredible midrange.

Also, rolling the small (12AX7 and 12AU7) tubes is as meaningful as the output tubes.