Genelex Gold Lion KT-88 reissued tubes

Has anyone purchased these tubes and what are your impressions of the sound?
Don, go here:

and click on tubes > kt88, for a very interesting history and survey of all kt88 tubes, new and old. Neil
Thank you Neil, very helpful info!
Don, my new McIntosh MC 275 Mk IV came with Russian Svetlana "S" KT88's (branded 'McIntosh', but that's what they are) and they sound wonderful, 'course I haven't heard anything else (yet) but I've no complaints. Mac also uses Electro Harmonix KT88's I understand. Those two along with JJ's tubes (the former Tesla) seem to be the most popular and reliable.
I just recieved my MFA 200D's back from modification by designer/friend Scott Frankland and after trying all the standards he decided on the reissue Gold Lions...the amps use 6 per side and put out 120 watts in Triode.
It is hard for me to just judge the tubes as they are one of several changes made to the amps, but Scott, who obviously knows his amps, went through a step by step process to optimize the amps and these are the tubes he chose.The amps have met and exceeded all of my expectations...very good to great with the changes.
I have used the originals (still have 4 NOS)in a very different design (audiopax) and find similarities in the fullness and richness of the sound...not euphonic or slow sounding.
From what I'm reading the KT88's add a little more warmth to the sound in comparison to the 6550 tubes. I have Tung-Sol 6550 reissues in my ARC VT-130 and would like to add a degree of warmth and richness to the sound.
Don, I have no experience with the Tungsol 6550s but a lot of experience with Sovtek and Svetlana Winged "C" 6550s in my ARC M300 MkII amps (the "C"s were excellent, Sovteks suck ;--) Here's my take: ARC amps, although they will work with KT88s, were designed around 6550s. In addition, ARC amps are not characteristically "tooby" sounding - not hard like some SS but still very neutral. My point is that changing to KT88s would give you a little more poop (bass control) but probably not warm things up that much.

With regard to the McIntosh amp I use now (and though I haven't tried this myself) those who've tried both report that the KT88s have more sparkle and slam than the 6550s, so go figure!

If you haven't had or done (it's easy) the capacitor upgrade on your VT-130, you should. The parts are only $200 from ARC and that would be a genuine improvement to an already great amp. If you want to try KT88s go ahead, but you may not hear that much difference.
ive had them for a couple of weeks in an audiopax amp and i like them so far. I've previously had the Penta and the JJs and like these reissues better than both - the bass is very good and overall they have a very rich sound. Carol
Neil, yes the caps have been changed. I do like what these tung-sol tubes do. It's always fun to bring out a little something different in the sound. I would say this set-up does sound rich, just not very rich. I should give the McIntosh a listen! Don
Don, BTW, if you do want to try KT88's in the VT130, DEFINITELY call ARC first and check to see if it's OK. There may be certain precautions, or restrictions depending on the model of ARC amp you have. Ask to speak with Chris Ossanna in service. He knows everything by heart ;--) If you want to stick with 6550's and want to try something other than Tungsols, I can definitely recommend the Svetlana Winged "C". (Try for best price and great matching.) I have also heard good rumors about the new Electro Harmonix 6550's.
Neil, I just purchased some Svetlana Winged "C" 6550 tubes. Waiting for their arrival and looking forward to the sound. Yes, best to stay with what the amp was designed to use.
There seems to be some significant price differences for these tubes, going from $220 per quad to almost $340 (delivered). I'll wait until the price stabalizes to try them in my Rogue 120's since I need 8. I guess this is a situation of whatever the market will bear will be paid, thanks for the extra $120 (per quad).
Hello Timsom,
I just read your responce to the Gold Lion KT88 post and was wondering if you ever got around to ordering them? If so what is your opinion ?
I too wish to try them in my M120 magnums.
I had the a bad experience with Yugoslavic Teslas. And although they were trully head and shoulder above anything else I've heard before or since , I hate to take the amps back to Rogue every time a tube went bad and after 3 trips to PA. I trashed the remaining tubes at a hefty lost .
I found the gold lions at for 199.99 a quad and Cryo treated at that but have yet to hear anything about improved or deminished sound quality after treatment.
Your thoughts welcome.
Thanks Roger
I ordered a quad of the Gold Lions today from, which operates an eBay store. The price was $195 for a platinum factory-matched quad. According to New Sensor, "platinum matching process consists of a 24 hour tube burn-in period followed by a bias (plate) current measurement in milliamps." The factory matched tubes then have the measurements on the boxes, etc. I can't say how this matching process compares with the matching done by the reputable tube sellers, but the factory burn-in may be a good quality control check. Anyway, that's how I've chosen to go. C Tech also sells factory matched octets, fwiw. I'll report back. My amp is a Music Reference RM-200.
Have been using Genelex Gold Lion KT-88 reissued tubes for about 6 months and like them, a lot. Have switched to other amplifiers during this period, always nice coming back to them. Did use GE 6550's and tried some Russian tubes before, like these better, but has a lot to do with the type of sound you are after.
I am currently using both the Tungsol 6550's (in an Audio research Ca50) and the Gold Lion KT88 re-issues (in a Cayin A70t) These tubes are quite different sounding. The Tungsols being smoother with a rich midrange and have been ideal for warming up the (to my ears) thin sound of the ARC products. The Gold lion's have incredible extension on both the top and bottom and have a very clean but not dry midrange. Probably the best way for me to describe it is that the difference in sound between the triode and pentode modes of my Cayin A70t (which with the Cayin supplied KT88's was Dramatic) has been reduced to barely noticeable. This is far and away the best KT88 I have heard. FYI, I also currently own Sovetk KT88's,SED 6550's,Original Svetlana 6550's, GE 6550's and Valve Art KT88's for comparison. Hope this helps.
Geraldm121, Did you by chance try the 6550's in the Cayin and the GL's in the ARC? I'm using SED KT88's in the Cayin and I'm curious. I tried some SED 6550's and found them a bit dry in that unit (they remain my 6550's of choice in other amps).
KT88's in general don't seem to do well in the ARC. I have not tried the Gold Lions but I did try the KT88 Cayin/Shuguangs that came with the Cayin. They were very hard sounding (almost like bad solid state)and they came out immediately.
The Tungsol 6550's were quite good in the Cayin but not quite as detailed in the high end with a softer sound in general and a very lush bass. That said, I could live with that combination but I probably would change the 12ax7's from the the current Mullard re-issues to a crisper sounding tube like a Telefunken (which were too bright when used with the Gold Lions)or RFT. Currently the 12au7's in the Cayin are Telefunkens that I had saved for 20+years!
Well, let me provide a little different perspective. I've tried the KT-88 Gold Lion re-issues, and and sad to report their reliablity is very suspect.

I've had four different tubes go out, all withn 100 hours of use. They either experience bias runaway (get cheery red), or they perform a very intensive blue light show, which will promptly take out the associated bias resistor.

All in all, while they do sound good, what good is that if they dont last, and take out your parts? I checked with a well respected audio shop in New York, and they more or less told me the same thing.

So, with that in mind, whats one to do? My stash of GE 6550A won't last forever, so I'm looking for a good sounding RELIABLE 6550/KT88 type that sounds as good as the GE tube. I have one set of 6550C from late 95, and while they are okay, they are not in the same class as the GE. Any suggestions?
SED(Wing C)6550's. Rugged, dependable, excellent quality. I've had one bummer in the past 10 years and it was too hot to bias in properly so it never got used. I bought it about 7 years ago but didn't use if 'til about 3 years ago. No other problems before or after. No shorts or premature deaths. Excellent bass, linear thru the mid range and if anything a bit, but not much, soft in the highs (something that helps sometimes with some bright sources).

BTW, re the KT88's, are you by any chance the same fella that Jim McShane is talking about in AudioAsylum who lost 4GL's?

While I have had better luck than you with the Gold Lion KT88 re-issues I have also had excellent luck with The Tungsol 6550 re-issues. I am currently running them in 3 amps a CA50 ARC, Antique Sound Labs MG SI 15DT(single ended) and a McIntosh MA2275 all (so far) without problem. I too use the GE 6550's as my reference (I am down to my last well used quad) and the Tungsol's are the closest tubes I have heard to the GE6550 sound. I probably have 700>1000 hours on the pair in the ASL amp without problems. The CA50 will be the acid test however as it is brutal on it's tubes. Currently I probably have about 100 hours on that quad. Good luck.
Geesh, spoke to soon. 3 out of 4 Gold Lion reissue's failed within days of each other. Think I got about 7 months out of them. Liked the sound, not happy with reliability.
Fred, I was just curious: where did you buy those GL's?

As I said, I've not had a chance to compare the GL's w/ the Penta KT88SC's (it's about 50/50 which one people like better) but I've never heard of reliability problems with the Pentas. You might want to give them a try the next time. . . . . . . and they're a little less money too!
Hi Gerald,
I am also running tung-sol 6550 in a Cayin A-70T, and find the bass to be lush, mids and highs are sweet. I tried EH Kt88 in the cayin and found the bass to a bit thin and the highs a bit grainy.

Does the GLKt88 have better bass in the Cayin ?
I have the Genalex KT-88 reissues in my RM-200 and they work beautifully. A big improvement over the original tubes, as promised. Mine were factory matched, too.
The Gold Lion re issues have a tighter and deeper bass in the A70 than the Tungsol reissues. A leaner but not a thin or cold sound (they are not as lush).
Well, sounds like I am not the only one with GL problems. I tried another quad recently, thinking perhaps there production problems were resolved.

Sadly, the problems continue! I had two go Cherry within a week. I researched possible causes of this, and I am convinced that the tube itself is the problem. I think that over time, the internal alignments get altered, or the solder joint on the pins open due to heat, and runaway occurs as a result. I think the metallurgy principals (expansion and contraction) are at work here. GE spent a lot of time and effort getting the 6550A right.

So, where is a good source for the Penta KT-88?
For Pentas (and GL's too) I think Doug at does a great job w/ matching and general QC. His prices are very reasonable (I remember thinking his shipping charges were sane as well :-) Unlike some tube sellers whom I won't mention, he doesnt pretend to know what you (or your equipment) require. On the other hand, he'll warn you away from danger ;-) So call him if you have detailed questions -- just don't ask him what you'll like!
I run these in my Quicksilvers mid mono's
They work and sound great,I did not like them for the first 150 hours or so, as they were bright sounding,they mellowed out now, and are smooth now with great detail,tone and dynamics.
I would get them again.
Have cary v-12r's vertically bi-amping alon IV Mk II speakers. am very happy with the gold lion kt88 tubes. only had two go bad in 2 years. sound and imaging is superb
I replaced Groove Tube KT88's with the Genalex's in my MFA M120 amps and the improvements were dramatic. The GL's are lovely-sounding tubes at all frequencies. They're probably not even burned in yet,either. :)
I have also had problems with Genelex Gold Lion KT-88 thermal runaway causing damage to Jadis JA30. While they worked they sounded great but would not try these again no matter what the sonic benefit.
I also lost a GL reissue KT88 the other night. Heard a humming sound and one of the quad was glowing orange. The quad is less than a year old with about 200 hours on them.
Any tube can go bad any time -- this is not hot news. However, vacuum tubes were once the ONLY electronic valve available -- and for the most part delivered service with the same reliability as transistors -- and, believe it or not, often the same longevity.

Of the modern manufacture power tubes, the reissue Gold Lions, Pentas (Shuguang) and S.E.D. (formerly Svetlana) KT88's all provide remarkable levels of sonic performance, though still short of the best vintage tubes. In terms of reliability, only the Electro Harmonix seemed to have continuing problems. McIntosh recently dropped them in favor of the S.E.D for their OEM KT88.

Of the current manufacture KT88's, only two have the air and sparkle of the vintage Genalex/GEC KT88's from the UK ($800 -- $1400/quad): the E.A.T.'s ($1600/quad) and the new Shuguang Treasure Series Premium Grade ($350/quad -- $650/quad depending who you buy them from). I've not heard the E.A.T.'s but I have the Shuguangs and they equal my NOS Gold Lions sonically. Now let's see how long they last ;--)
I just replaced my (8)EH KT88's in my Cary 120S amp with 8 Grade A Shuguang Black Treasures and also replaced the 2 driver and 2 input 6sn7's with Shuguang Black Treasure CV181Z's. The amp sounded very good with the EH tubes but the Treasures redefined this little Cary. Every aspect of the audio performance has been elevated to levels I thought were impossible. The tubes have about 90 hours on them and I am told they will improve with more hours. My Preamp is the Cary SLP 03. I have TJ Full Music 12AU7's coming and can't wait to try them out (EH 12AU7 replacements) The speakers are Harbeth Compact 7ES3. After 40 some odd years it seems like just maybe the SEARCH is over. I can honestly say the Shuguang tubes have been the single largest improvement I have ever made in any of my many audio systems over the years. Dave Hubbard
I also changed to the Shuguang (but not the Black Treasure) and have been very happy with them. Had them several months now. No more Genelex.
I run a pair of Sonic Frontiers SFM-160s which each use a MQ of GL KT-88s. The amps were bought used, then shipped directly to Chris Johnson for a comprehensive check-up and his SE+ mod. The GL KT-88s were "standard" issue for the SE+ mod.

That was two years ago. Since then, I have lost three GLs on three separate occasions, each time taking with it passive parts in the amp. The most recent episode was 90 days ago. I retubed withe MQ from Chris J when I had the amp repaired (locally). So far so good, but I am getting nervous (and broke).

Chris J would like me to consider the Tung Sol KT-120. He told me that the KT-120s are more reliable, the power transformer of the SFM-160 has more than ample current reserve to handle the 0.8 A increase in filament current draw and the KT-120s can take the punishment the SFM-160 delivers.

However, though still very premature, I have received mixed and even a few negative comments on this tube.

Any comments on the KT-120? Other quality options for 6550/KT-88 amps?

Flyfish2002, First, consider that the KT120 has only just recently hit the market. Other than its rating there is little to substantiate a recommendation for 'reliability'. But, the spec's are impressive and I can understand why Chris would recommend them as an alternative.

FWIW, I have some SFM's in my attic which I purchased used. The previous owner had problems with tubes in it (he was using KT88's not know for stability) and gave up out of frustration. I used SED 6550's - had no problems until I plugged in a 'rugged' KT88 and one went and took out a cathode resistor. I had it repaired and recapped - after which I lost one of my SED 6550's in one. Now they just sits in the 'attic' - I need neither the power nor the hassle of hauling it to the techie.

I'm not dis'ing these amps, they sound fine, its just that they were designed around a very rugged tube (EI KT99), which haven't been available for a long time, that could handle the very high plate voltage of these amps (650 as I recall - read your manual for exact specs).

Thanks, Newbee. I am not ready to throw in the towel just yet. These are well-built amps that with Chris' top end mod provide me with alot of enjoyment. I like the SF house sound and am on the hunt for a cream puff pair of Power 3s - fully balanced and no issues with over running tubes.
sound-wise they were great but my matched quad from Jim McShane went south on me in 4 mos. (wouldn't hold bias in both channels) normally i get about a year out of a quad of EH's before they lose their sparkle. i won't buy the gold lions again. i think i'll try the shuggie's from Mr. Deal next...the cheap ones...350 is out of my league

What is a "shuggie" from Mr. Deal?

So the GL KT-88 just didn't hold up for you as you would have expected - 4 mos is crazy. Jim McShane is purportedly one of the "good guys" in tube audio. Did you communicate back to him?

shuggie's are from upscale audio...the shuguang (sp?)kt88's. the gold lions i got from jim were well out of warranty & they are tubes so it can be expected occasionally. both mcshane & deal have always been top knotch
I'm considering replacing my Winged "C" 6550's in my MFA 200D monoblocks with the Gold Lion KT88 reissues. I need a total of 12 tubes so it is an expensive purchase.
I've been seeing a lot of reliability issues on this thread and was hoping to get more input from users of this tube.
I'm also curious about the sonic differences between the Winged "C" 6550 and GL KT88's. Another possibility would be the TUNGSOL 6550's.
The MFA 200D's are pretty powerful amps. 120 watts triode/220 ultra linear. The speakers I'm using are Harbeth M40.
I appreciate your input and hope to hear some helpful responses on the subject.
Frank, I haven't heard the Gold Lion re-issues, but I have and use both the SED 6550's and the Tungsol reissue 6550's. In my amps the 6550's are neutral, linear, rugged, and clear toned tube which are not overly extended. They don't favor any part of the frequency response. The Tungsols have more bass and are perhaps a bit soft in the highs. Mid-range is quite nice. A great tube if you are looking for more warmth from a cool amp or speakers. I haven't had a Tungsol fail yet either so from my POV they must be rugged.

My impression from what I have heard is that the GL's are SED's on steriods. If you decide to try them be sure to get them from someone who will thoroughly test and stand behind them like Jim Mcshane.
Thank you newbee for the response. I have Harbeth M40 speakers that are an inefficient load. The bass response is on the loose side so if the KT88's will have more control on the bottom end, I'd definitely like that. I also could use a little more top end as well so the Tungsol sounds like it may not work for me.
@ Flyfish, Newbee:

I am driving a paif or Martin logan Summit X's with two McIntosh 275's, and additional power would be welcome. Using a KT-120 sounds interesting, but here is my question:

If an amp is Class A, that means it's operating the tube in the middle between zil and maximum voltage (or current? IDK). If the upper boundary of voltage is raised due to a better tube, can a class A amp actually benefit from it? My logic says no, but I'm no expert.

Put a matched quad GL KT88 in my Yaqin 100b. Could not believe how good they sounded. Within 2 months, two could not register a bias, a third went alarmingly hot and orange and blew a channel (resister). My learned repair person was very anti this GL reissue. Replace them with JJ's. I'm back, but it's going to be hard being satisfied without that GL reissue sound, but they are just too expensive to keep replacing. What's better than these JJ's?

Like so many others have posted here, I too had Genelex Gold Lion Tubes fry (with likely no more than 150 hrs on them) and take with it my amp. In any event, the shop made clear that the Genelex KT88's failure was the culprit. So... I guess I am numbered alongside a half dozen others here who have had the Red Lions go down.

This seems to be ample reason to stay clear of the Red Lions.
Typo on the last post --- they are Gold Lions --- not Red Lions... perhaps it was my anger over how readily the Gold Lions fry that I had the color red in view.

So... stay clear of the Gold Lions... unless you are OK with replacing them often.
Larryrup Perhaps you can try the Chinese tubes from Shugaung (spelling?). My tube guy says they sound glorious --- but are also thought to be unreliable (like the GL tubes... maybe worse).

It is frustrating, this tube thing ... like a high maintenance wife who is awesome --- and who you cannot live w/o who is, at the same time, really, really tough to live with. So it is with tubes... can't go back to SS after living with these babies... but the lack of reliability is horrible --- so... about all you can do is enjoy the tubes when they work and prepare for trouble when they fail.
Hey everyone. This thread is now 4.5 years old, and so I thought I'd throw in my 2 cents concerning many of the earlier concerns/experiences people had with the available offerings back then. I still stand by my results/conclusions as reported in my last post on 4/7/10. And my Shuguang Black Treasures have been running reliably 8 hours/day +/-- for the last 18 months. From time to time, I swap them out with my (very strong testing) NOS Gold Lions just to see if the Shuggies are holding their own sonically, and they are. It's so easy to overlook deteriorating performance in many parts of an audio system (just with normal use) when nothing actually blows up! Not just tubes, but TT bearing lubrication, dirty connections, etc. However, the Black Treasures (still $360/quad premium, shipped from China) sound just the same today, against the vintage Gold Lions ($800--$1400/quad used,) as they did right after their 300 hour burn-in.

If they are still the same after another six months, I may just go ahead and sell my two remaining quads of GEC KT88's, buy a spare quad of Shuggie Blacks, and spend the extra $1500 on some new vinyl! (You can't spin tubes!)