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


Just picked up a new Jadis today, and I'm none too pleased with the sound. As I have had blissful sonic experiences with two of the models lower on the Totem Pole from this manufacturer, the only thing I can trace it to is the Sovtek 6550. Can they really be THIS bad???

I already switched out the JAN Philips 12AX7 and Golden Dragon 12AU7 for Mullard Blackburn and Ei respectively. The improvement has been subtle, but it still ain't working for me...

I have used ElectroHarmonix 6550 in the past, and while they didn't float my boat, I'm told that EH represents a signficant step up from the regular old Sovteks. JJ E34L and KT88 just have sounded really splendid to me. So, now I'm looking at picking up 8 new output tubes if I don't wish to live with such uninspired sound.
You're right, Sovteks suck. They didn't always, but they do now. My favorite 6550s are the winged red base Svetlanas (from St. Petersburg), available matched, burned in, and at an excellent price ($54.95 matched pr.) from: in Canada.

PS: I noted some other folks had another good recommendation for 6550s. I wish I could remember what it was, but it wasn't EH. Maybe if you search these forums you can find it.
can't tell ya about 6550 sovts but EH to my experience has a record short life that may be very distructive to the component circuitry.
i've used eh EL34 and will never place them again in my VTLs. i now use either svets or yugos. during 1+year period measuring the bias i found that it didn't change even slightly.
therefore i suggest
#1 ask manufacturer if it's OK to go with EH since some of the brands are OK... i assume that EH lack the lifespan to all other tubes significantly in any component
#2 find yourself the best match for performance/reliability and nevertheless budget as well.
Come on, Trelja you been around for awhile. "new Jadis today." Can we say burn in time :) I wouldn't even look at rolling tubes till 200 hours of burn in.

I have Soveteks el84's in my Yarland with no complaints.

BW MaxxC
Yes and I wouldn't fret over changing them.
It sounds to me like it may be a problem with the unit. Are you sure it is functioning correctly? If you have liked the sound of this companies equipment in the past I would think that it is odd that you need to start flipping tubes so quickly to get it to sound right.

Chuck, you're right, it could be something else. I'd have to hear it in person to make even an educated guess.

what I do know is that when I swapped (all sisteen!) of the Sovteks in my ARC monoblocks for the Svetlanas, it was like night and day. True, the Sovteks were getting old, but still functioning. In any case, I sure was happy with my decision.
Thanks for the replies. Of course, it is possible that something is wrong. That cannot be really known until I retube.

One thing is for sure, it won't be with 6550. I'll get two quads of JJ Blue Glass E34L. Because of my impatience, I was thinking of trying my quad of JJ KT88 in one channel just to see.
A few years ago I changed the Sovtek 6550s to JJ Tesla KT88s in the ARC VT130. Wow, the musical enjoyment was dramatically improved.....until a tube blew. These KT88s did not seem to have a very good reliability. Several went out around the 6-month mark. And unfortunately, when they did, they took out a power resistor in the amp in the process. It was easy to resolder in a new one, but it was a hassle to put up with these tubes. So be forewarned about this issue. Perhaps they have imporved over the last few years.
EH is made by Sovtek, in case you didn't know. Some EH's are said to be selected as the top-testing tubes from regular Sovtek runs, others seem to be exclusively EH offerings (the gold-pins, and some of their "copy" tubes like the 6CA7.)

That said, I've owned Sovtek KT88s and thought they were pretty bad, but I could be happy with their 6922s (a preamp tube.) For EH, I've owned the EL84 (okay), the EL34 (not very good) and the 6CA7 (fat bottle EL34 - better, but still prefer KT88s) as well as a couple preamp tubes I haven't any memory of. Svetlana (originals) and EI (Yugo) beat Sovtek and EH in all encounters I've had, though I still remain surprised by the Sovtek 6922 - mainly for their bass impact.

That said, these are all opinions, and system matching of course always plays a big part.
maxx makes a good point yoy need to let the unit burn-in for sometime before you start flipping tubes.

Hi Trelja. I assume this is the new DA60? And it's been burnt in? The JOR didn't sound great for a week at least, and then when the store replaced all the KT90s in response to only one being faulty it took another few days just for the tubes to sound fine again.
I recently plugged in the old ARC D125, which has eight 6550Cs, Svetlanas, and it sounded as good as I remembered it to be - different to the JOR obviously, but good - the only other brand of tubes this ever had were old GE 6550As, and the Svetlanas killed these.
All the best, Rob.
I recently bought a pair of used VTL 750's from an authorized dealer who had completely re tubed these amps with matched Sovtek 6550's.

These particular tubes were TRADE MARKED as "Svetlana" which are the same tubes as Sovtek / Electro Harmonix for those that don't know the name Svetlana was bought by a large distributor.

The dealer said they had 200 hours on them and testing with my Hickok 752A tester showed no shorts, no gas and "new" transconductance readings.

After listening to these for about a month, and unable to get rid of high frequency distortion and dissatisfied with imaging and dynamics, I replaced all 24 Sovtek/Svetlana 6550's with new SED Wing C 6550's.

The upgrade was almost equivalent to replacing the amps. Everyone who visited the next Tuesday listening session (with only 10 hours on them) asked where the upgrade came from.

Can't wait to hear what the Wing C can do when they are completely settled in. I think this is the best new 6550 around and as others have already commented, the Sovtek may be the worst.

If anyone wants these Sovtek / Svetlana, I will be practically giving them away. Look for on an ad at Audiogon soon.
I feel I should add this for those that don't already know.

The Svetlana 6550, EL34 (etc) of three years ago is the SED Wing C of today.

Those who sing the praises of Svetlana bought some time ago are saying they like the (present) SED Wing C.

Same tube !

It's unfortunate that this confusion exists. The trademark lapsed or was negotiated for, I don't know the legal part involved.

Bottom line is the names Sovtek, Svetlana, Tung Sol, Mullard and Electro-Harmonix are all owned by ONE COMPANY. They market various tubes, very similar in construction, and all produced in the Reflector (Reflektor) plant in Russia.

SED Wing C was the previous owner of the name Svetlana and responsible for giving it the sterling reputation that made the trademark valuable. The SED is built in a completely different factory in St. Petersburg.

Hope the above explanation helps more than confuses.
someone mentioned you have the DA60??

if so, I encountered the same issue you had with this amp. I bought one about 2 years ago and was blown away with cosmetics, impressed with the build, ..I had high high hopes.

I had upgraded from the Jadis cheaper integrated......

i tried Ge6550s, el34s, kt88s, swapped out the small signal tubes but just could not get this amp to sound "tubey". ....Jadis had always been described as warm and tubey in regards to the Defy7,.....I concluded that the Da60 and the other integrated was just a darker sounding tube amp.....not my taste...I sold the Da60 and went to Air Tight amps and have not looked back
Albert, the Svetlana tubes sold on the website I mentioned here earlier, are indeed the ones manufactured in the St. Petersburg factory. They are listed on that site as SV 6550C, whatever that means. I've done business with Eugene, (a Russian BTW) and he does a great job matching them, basically at no extra charge, because that's the only
way he sells them.


Cool, further explanation of why you like and recommend them. We choose the same tube :^).

The name change is very confusing, probably only helpful to the new trade mark holder who is selling off the reputation of the previous factorys work.

As for comments by Justlisten, I would take that to heart. By no means am I suggesting the answer to your problems are switching to the same tubes I bought.

I do think it's important for everyone to report their experience with performance of various tubes so each can make up their own mind.
Maxxc, the "new" Jadis for me is actually a used amplifier, so it's already burned in. My experience is that Jadis amps take a good long time to burn in, but such is not the case this time. $11,800 is more than I could swing, as much as I'd love to buy from Pierre Gabriel - VERY good guy.

Albert, your Sovtek 6550 story makes me wonder why anyone would use this tube, beyond price. Well, maybe that's the reason? Anyway, again, after my past experiences being around ARC, CJ, and VTL amps, and living with this tube and the EH6550, as I have said many a time, I'm simply not a fan of the 6550. The JJ KT88 has sounded better to me in every application. Yes, it's more expensive, but the price is a pittance in comparison to the sonic benefit.

Justlisten, this is my third Jadis. I began with the JOR, which was sublime with JJ Blue Glass E34L. Best midrange I have yet to hear from any amplifier. Next is the DA30 that I still own. Also fantastic, but much different from the JOR. It's strength is a luscious midbass - lower midrange and an overall sweet tone. I could use a bit more power in some situations, which led me to the DA60. Neither was dark sounding. I was most happy with each of them.

So far, this DA60, built like a beast as you have said (1975 Arnold power transformer - the DA30 looks like girly man in comparison), seems lacking in excitement sonically. I now have Mullard Blackburns in the 12AX7 and 12AU7 positions, and while things are looking up, I could still use bit more of the jump factor.
Joe (Trelja),
My CAT JL-2 uses 16 6550s and sounds great. I don't know which 6550s are in it b/c its away right now. When it comes back, you're welcome to come over and have a listen.
Bob, it's great hearing from you! I'd really love to hear your CAT once it returns home. Knowing you, I'm sure it sounds lovely in your system.

I spent a good amount of time listening last night, and interestingly enough, the faults Albert attributed to this tube are EXACTLY what I heard. The dynamics are weak, and the sound just seems to lack the get up and go I demand. The high frequency distortion was also there in spades. Most curious was that female vocals took on a peculiar "lip smacking" effect where there should have been breathiness. Imaging was not terrible, but not up to the standard set by the JOR.

I did try the quad of JJ KT88 in one channel, and that seemed to help out a fair amount, but I was still getting the Sovtek 6550 effect masking the overall sound, so I am not 100% certain if a retube will cure things.

I went back and forth with the DA30 a couple of times, and it had a snappier, more lively, and easier to listen presentation. It's really a superlative amplifier, apart from ultimate power and not being the last word in imaging. My DA30 is one of the first integrateds Jadis ever built. I have been told by two people that later iterations modified the circuitry to enhance thermal stability of the amps, which has NEVER been in an issue with mine, at the expense of sonics. May very well be true in my experience. What it lacks in cosmetics, it sure makes up in sound.

The one combination I should have tried in retrospect was the Sovtek 6550 in the DA30. That would perhaps answer a lot of questions.

Still, this is the amp for the second system, and I'm probably putting way too much effort into the whole thing...
Joe, I might forget about this. Send me an email message in a week or two. If the amp isn't back I should at least have an ETA. Bob
Hi Trelja. Thanks for mentioning the possibility of the JOR being "loose" - I took this to mean that the little bolts on the casing could be loose, and sure enough tightening them virtually eradicated the hum - presumably the service guy who biased the new tubes left them a bit undone and so the casing amplified whatever resonance the transformer was creating.
Hope your new amp works out. Regards, Rob.
Bob, will you be coming over next Saturday??? Hopefully, the answer is yes.

I did try the Sovtek 6550s in the DA30 last night, and I must say that while the amp runs out of steam before its big brother, though still within the limits of being acceptable to all but the really power thirsty, it's simply a better component sonically. Even with these tubes, while not as glorious as the JJ KT88, the sound was commendable. Despite its homely looks, whatever purity was designed into it originally, later iterations seem to have lost to some degree. Not that the DA60 is not a very good amp, it is, just that the older amp is INCREDIBLY special. The sweetness, naturalness, and even excitement is wonderful. I guess, sometimes, the old stuff really is that good.
Rob, I'm so happy about the JOR not having a "real" transformer issue. That would be quite painful.

You read me 100% correct in my saying "loose" meaing what you thought it meant. My idiotic ramblings are so all over the place, it's a wonder anyone can understand me sometimes. It's easy to see how a loose transformer could really buzz. The biasing of the amp should not involve loosening the transformers whatsoever, only reading a few resistors, and adjusting the respective potentiometers until the voltages on those resistors falls into spec. Still, I'm sure it could have loosened any number of ways.

Good luck with that JOR, it's one of the finest sounding amps I have ever encountered, if not the finest.
I need to make a correction. I think the stock tubes for my CAT JL-2 are 6922--and I haven't changed them.
You're still welcome to come over and have a listen of course.
Well, after spending a few more days trying certain things, and talking to a few people, I wanted to update things.

In my situation, the crux of the problem is NOT the Sovtek 6550. I wanted to clarify that I have been listening to them in my DA30, and while certainly no match for the JJ KT88, they still allow the Jadis sound to assert itself. I feel obligated to let everyone know that while they are not going to become my favorites, they are not the root cause of the poor sound I am experiencing.

I guess for many, sadly, they would not think anything was wrong with the DA60. However, I have become quite familiar with the Jadis magic, and this amp does not possess that. Amplifiers from other companies simply do not have it. Someone not familiar with it might not be able to tell, but I was. And, it is through no fault of the tubes. While a legitimate Jadis, I have discovered the amplifier has been modified by folks who have somehow bled what is special about a Jadis out of it. And, along the way, have done a lot of wrong to the amp, manifested in the way it works. This was in no way devulged to me by the seller, and the amp was listed in very good - excellent condition. I am not sure what my recourse is. But hey, caveat emptor, I bought a used component. Though I have purchased new Jadis products, as I said, there was no way I could swing $11,800 for this integrated. Worst case scenario is that I have found a person expert in Jadis, and has the ability to get the DA60 to where it should be. At which point, I can accurately determine how it compares to my JOR and DA30.

But, again, I feel it necessary to make sure I apologize to Sovtek in regards to their 6550 output tubes. They are NOWHERE as bad I initially inquired about,
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.

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.

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.