Anyone Compared the New 6550/KT88s out there in their Amps?

MylesBAstor

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There are quite a few choices for 6550s today. I use the cj supplied Svetlana 6550C SED in my amps.

Has anyone tried the new Gold Lion KT88 replicas, Tungsol 6550, EH 6550s, Shuang Treasure KT88, EAT KT88, etc? If so, what do you think about the sound. How reliable have they been?
 

MylesBAstor

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Myles

my good friend Marty who is a member here is an expert in this very question and i am going to see if he will post a response

Excellent! Looking forward to Marty's findings!
 

marty

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Like all things audio, tube preferences are personal

The first issue to discuss is 6550 vs KT88. Let me state unequivocally that I am not a fan of 6550s as I believe the KT88 is simply a far more musical tube. 6550s have an inherent grain structure in the upper midrange that is rather characteristic of the tube style regardless of manufacturer. Having long ago substituted KT88s in my ARC Ref 300 MkII amp (when I had them) for the stock 6550s, I strongly believe that an ARC owner who has not tried KT88s in his amp doesn't know the true musical potential of their amplifiers. Unfortunately, ARC does not support KT88s (unlike VTL) so you have to do it at your own risk. Fear not, the bias is identical and the switch should be seamless. IF KT88s are more "musical", why does ARC provide only 6550s in their amps? The reasons, according to Dave Gordon, are twofold. First, they feel it is a better overall tube for full range performance. In other words, they like the bass performance of the 6550 over the KT88 and thus install 6550s with that in mind. The 6550 tube does have slightly more powerful bass, but in my experience, the KT88 has perfectly good bass as well, with the added benefit of sweeter mid and top end performance over the 6550. Kevin Hayes at VAC, and the folks at Quicksilver, prefer KT88s in their amps for full range performance. The folks at VTL will let the customer decide, and will supply their amps either way upon request. The second reason ARC prefers 6550 is overall tube quality and reliability. On this point, I simply do not agree. My failure rate appeared similar for both. I think this is more a function of the amplifier and application than the tube per se, but I may be wrong. As all tube owners know, any output tube can fail. If you cannot accept this risk, which could be considerable, you should probably stick to solid state designs. Fortunately, using VTL Siegfrieds, tube failure is easy to deal with. The outstanding protective circuitry will shut the amp down before it goes nuclear and an indicator light will tell you which tube to replace. Thirty seconds later, you're back in business after a fast tube replacement.

Regarding KT88s I am not a fan of the famed SEDs from Russia. Once again, IMHO the Shuguang factory is making the best tube of this type on the planet. As already noted, Keivn Hayes feels strongly about the Shuguang tube as well. These are available in several iterations and bottle shapes. The beautiful Shuguang 88-98 is available from several sources. This is also identical to the Valve Art KT100 (sourced from Antique Electronic Supply in AZ, the importer) and has a similar counterpart by PentaLabs, both of which are OEM'd by Shuguang for these labels. PentaLabs also has a proprietary, solid plate "3 getter" version made by Shuguang that is available from Doug's tubes (a fantastic vendor), which I've also used and like very much. The Shuggies are spectacular tubes but again, keep in mind that this is a highly personal choice. I certainly have not tried all the possible manufacturers of KT88s. I am tempted to try the Gold Lions as I have heard good things about them even though they are a Russian tube made tube by New Sensor.

One of the most important aspects of output tubes is the quality of the vendor as far as tube matching and overall service. I adore Doug at Doug's tubes (http://www.dougstubes.com), and the Tube Store in Canada. The Tube Depot in Memphis does a good job, especially for the SED 6550 (they are the US importer). The folks at Upscale Audio in California also do a good job of testing and matching, although in my experience they have "attitude" issues that are hard to take, even for a New Yorker!

If anyone has done a direct comparison of Gold Lion KT88s to another KT88 brand, I'd like to learn your thoughts.
 

RUR

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The folks at Upscale Audio in California also do a good job of testing and matching, although in my experience they have "attitude" issues that are hard to take, even for a New Yorker!
Good to know it isn't just me.;-)

I've used the GL KT88's in both Rogue M-150's and VTL MB450's (in which they were much superior to the VTL-supplied 6550's), but I've not compared to the Shuguang KT88's. Purchased the GL's from Jim McShane, whom I highly recommend.
 

MylesBAstor

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The first issue to discuss is 6550 vs KT88. Let me state unequivocally that I am not a fan of 6550s as I believe the KT88 is simply a far more musical tube. 6550s have an inherent grain structure in the upper midrange that is rather characteristic of the tube style regardless of manufacturer. Having long ago substituted KT88s in my ARC Ref 300 MkII amp (when I had them) for the stock 6550s, I strongly believe that an ARC owner who has not tried KT88s in his amp doesn't know the true musical potential of their amplifiers. Unfortunately, ARC does not support KT88s (unlike VTL) so you have to do it at your own risk. Fear not, the bias is identical and the switch should be seamless. IF KT88s are more "musical", why does ARC provide only 6550s in their amps? The reasons, according to Dave Gordon, are twofold. First, they feel it is a better overall tube for full range performance. In other words, they like the bass performance of the 6550 over the KT88 and thus install 6550s with that in mind. The 6550 tube does have slightly more powerful bass, but in my experience, the KT88 has perfectly good bass as well, with the added benefit of sweeter mid and top end performance over the 6550. Kevin Hayes at VAC, and the folks at Quicksilver, prefer KT88s in their amps for full range performance. The folks at VTL will let the customer decide, and will supply their amps either way upon request. The second reason ARC prefers 6550 is overall tube quality and reliability. On this point, I simply do not agree. My failure rate appeared similar for both. I think this is more a function of the amplifier and application than the tube per se, but I may be wrong. As all tube owners know, any output tube can fail. If you cannot accept this risk, which could be considerable, you should probably stick to solid state designs. Fortunately, using VTL Siegfrieds, tube failure is easy to deal with. The outstanding protective circuitry will shut the amp down before it goes nuclear and an indicator light will tell you which tube to replace. Thirty seconds later, you're back in business after a fast tube replacement.

Regarding KT88s I am not a fan of the famed SEDs from Russia. Once again, IMHO the Shuguang factory is making the best tube of this type on the planet. As already noted, Keivn Hayes feels strongly about the Shuguang tube as well. These are available in several iterations and bottle shapes. The beautiful Shuguang 88-98 is available from several sources. This is also identical to the Valve Art KT100 (sourced from Antique Electronic Supply in AZ, the importer) and has a similar counterpart by PentaLabs, both of which are OEM'd by Shuguang for these labels. PentaLabs also has a proprietary, solid plate "3 getter" version made by Shuguang that is available from Doug's tubes (a fantastic vendor), which I've also used and like very much. The Shuggies are spectacular tubes but again, keep in mind that this is a highly personal choice. I certainly have not tried all the possible manufacturers of KT88s. I am tempted to try the Gold Lions as I have heard good things about them even though they are a Russian tube made tube by New Sensor.

One of the most important aspects of output tubes is the quality of the vendor as far as tube matching and overall service. I adore Doug at Doug's tubes (http://www.dougstubes.com), and the Tube Store in Canada. The Tube Depot in Memphis does a good job, especially for the SED 6550 (they are the US importer). The folks at Upscale Audio in California also do a good job of testing and matching, although in my experience they have "attitude" issues that are hard to take, even for a New Yorker!

If anyone has done a direct comparison of Gold Lion KT88s to another KT88 brand, I'd like to learn your thoughts.

The tube I wanted know about the most you haven't tested eg. the GL reissue :) And now that I'm getting the big, new cj ART amp with 16 tubes, I'm less inclined to experiment because of the cost of the tubes.

Years ago when I had my cj MV75A1s, I stuck real GL KT88s in the amps. I agree about the sound of this KT88, extremely transparent and detailed. Would love to know if the new tubes are close!

I'm not so sure about the 6550 "grain" in the cj amps. I might submit part of that grain also is due to the type of caps used. I find the Teflon caps get rid of this dynamic compression in the upper midrange as well as smoothing out the sound w/o losing detail. I've also tried some of the new Mundorf Au/Ag oil caps in my new Cello based tape preamp and they are outstanding. They beat what was in the unit (Sidereals--that I've never been a fan of) by a huge margin in just about every way. In fact, it was a wipeout in favor of the Mundorfs with better bass, more midrange, more weight in cymbals, more transparency, etc.

Thanks a lot for sharing your insights Marty!!!
 

nsgarch

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There are quite a few choices for 6550s today. I use the cj supplied Svetlana 6550C SED in my amps. Has anyone tried the new Gold Lion KT88 replicas, Tungsol 6550, EH 6550s, Shuang Treasure KT88, EAT KT88, etc? If so, what do you think about the sound. How reliable have they been?
I'm not familiar with cj's current oem tubes, however they can't possibly be both SED's and Svetlanas as your comment implies. You have either the Svetlana-branded new tubes (made under an old name purchased by New Sensor Corp.) or you have S.E.D. made in (what used to be) the original Svetlana factory in St. Petersburg. So today's S.E.D. "Winged =C=" is really the same excellent tube that was manufactured in the (real) Svetlana factory (in St. Petersburg) for years.

As for the Shugggie KT88-SC, -98, and PentaLabs, they're all decent sounding, and more important, reliable. New Sensor's Electro Harmonix KT88's were/are terribly unreliable -- one reason I believe McIntosh recently switched to SED's. And the Shuggie KT88-SC (a true replica of the MOV KT88) is as good if not better sounding than the New Sensor Gold Lion KT88 (hardly a replica!), and at about two thirds the price. As for 6550's, well, in my opinion, it has to be the original NOS solid black or gray plate Tung Sols -- otherwise, as Bette Midler used to say, "Why botha??"

Now; should you want to leave all that mediocrity behind :), and step up to sonics that are in an altogether different league, you have three choices (until recently, just two choices): (1) NOS Genalex Gold Lion/Gold Monarch/GEC (2) EuroAudioTeam, EAT and now (3) Shuguang's Treasure Series KT88-Z.

I can't claim familiarity with the EAT's (I tried a quad of old and very tired EAT's; but my experience with those would not be fair to count.) The Shuguang Treasure Series are like the NOS Genalex's (and presumably the EAT's too) in that they exhibit the same shimmer and sparkle that separates those two from all other KT88's. But the Shuggies go one step further. Even after only 30 hours, a tenth of their specified burn-in time, they produce a VAST soundstage. The sound is sparkling and alive, just like the NOS Genalex. However there is a 'gravitas', a body and weight to the sound that I've never heard from a KT88--based amp before. A Premium A, matched quad, cost me $357 incl. DHL airfreight from Shenzhen, China. At that price you can afford not to agree with me :D
 

MylesBAstor

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OK I was taking the designation off the tube boxes that just came in. On the top, it reads SV6550C and on the side of the box, SED with the winged C and www.sed-usa.com. Guess just assumed SV = Svetlana.

Thanks for the info-and well the new amps use 8-6550s per channel :) That's a good reason to be sure before plunking down the cash :)
 
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marty

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Wow. I was unaware of the Shuggie KT-88 Z. Thanks. May I ask:
How many getters does it have, 2 or 3? Also. can you provide a contact for purchasing? What is the source please?

BTW, I just retubed my Siegrfrieds with Genalex Gold Lions. Too early to tell yet (37 hours). But will update with a report at 100 hours.
 
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MylesBAstor

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marty

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Thanks Myles, but nsgarch said he bought a set of matched quad KT88z directly from China for $357 including shipping. The Tube Store (excellent vendor) charges $500. Big difference, especially for 12 or 16 tubes.
 

MylesBAstor

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Thanks Myles, but nsgarch said he bought a set of matched quad KT88z directly from China for $357 including shipping. The Tube Store (excellent vendor) charges $500. Big difference, especially for 12 or 16 tubes.

Of course :) The only thing I'd be worried about is quality control there and selection. But the price is right.
 

nsgarch

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Wow. I was unaware of the Shuggie KT-88 Z. Thanks. May I ask: How many getters does it have, 2 or 3? Also. can you provide a contact for purchasing? What is the source please?
The KT88Z has (correction) two halo getters, both on top. The plates have three very large oval holes each side. Their internal structure is not like any other KT88 Shuguang makes. In North America, I recommend you purchase them from Dan at the TubeStore in Canada. You can purchase them from China also for a bit less.

Excluding the EAT's, which I admittedly didn't hear under optimal circumstances, my hands-down favorite, in my McIntosh MC275, and driven by GEC A2900/CV6091 (12AT7's) is turning out to be the new Shuguang Treasure Series KT88-Z. Here are some excerpts from a recent email exchange, which I hope will answer most questions:

Thank you for responding to my question on the TS KT-88's. It is comforting to know that Shuguang and Clark are doing their best to resolve the issues you identified with your KT-88's. Unfortunately, my tube tester does not allow me to perform the measurements that yours does. I usually measure my tubes when I receive them and take quarterly measurements to see if there are any changes to the measurements, as a means to determine tube life. Still wondering where to buy the tubes ($520.00 vs $350.00 from China). Also, I would like to hear from you how the new set of TS KT-88's measure up, when you get them.

I have about 175 hours on my (second) set of TS KT88's, and they already sound better than my NOS Gold Lions, which means they're as good as EAT's, (or maybe better?!) In fact, my friend Mark, who didn't know I'd received the new set, called this afternoon and hearing my system in the background, just casually remarked "Those Chinese tubes are really great!" just as he did with the first set -- only this time he knew it wasn't "the record"!) The boy has amazing hearing! I have no idea what the life of the TS's will be (and I bet Shuguang doesn't either!) but if they go 6000 hours, that would be pretty good. The NOS Gold Lion/GEC's went 10,000 hours and up! But these new carbon-coated tubes are an unknown quantity. They really do take 300 hours to burn--in. They don't take 300 hours to sound good; but their test values change (improve) as they burn-in, which is not typical of new power tubes which usually "settle down" after 20 hours or so. This is probably why the Shuguang factory only tests these new TS tubes for actual plate current (and not even under full load at that) and all the other values are only checked qualitatively. So who knows how long they'll last? ;--)) until they've been out in the field for awhile.
 
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nsgarch

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Of course :) The only thing I'd be worried about is quality control there and selection. But the price is right.
Myles, I totally understand your quality/selection concern with Chinese sources, however, in this case (Shuguang Treasure Series) I spent literally a month vetting Chinese sellers. Here are the results:
  • Don't buy from Chinese eBay sellers
  • There are in fact two grades of Treasure Series tubes -- A and B. They are really hard to grade right off the assembly line because of the long burn-in time required to "cure" the coating. The KT88Z's initial plate current (just a quick check, not under load) ranges from 30mA to 60mA. The B grade cuts off around 40mA I think. I presume (and I will find out when mine are fully burned in) that the initial Ip current number will go up to around 80mA under load, just like NOS GL's, and EAT's.
  • The Chinese seller I finally decided to to business with is a great guy, speaks excellent English, responds promptly, and has been groomed (by me!) as to the care and feeding of neurotic O/C Western audiophiles :D
  • At least half a dozen of the folks I have referred to him (only after playing the Guinea pig myself) have had an excellent experience. He has an office at the factory and can hand select tubes himself -- meaning if you tell him you want a quad with Ip not less than 50mA let's say, you might have to wait two or three weeks for a new production run, but you'll get what you asked for.
  • The price for the TS KT88Z's (-- he sells all the TS tubes) is $150/pair (the pairs will match if you want a quad) and $57 (per quad) to cover PayPal fees and insured DHL 3-business-day airfreight to your door. 90 day return/exchange policy. Is that service or what?
  • I have not published his contact information in any forum because I want to protect him from harassment by a certain Canadian seller (BTW, not Dan at the TubeStore!) I discussed the situation with Dan who is a great guy, and charges a bit more for the KT88Z's -- ditto Pacific Valve in Chicago. Go to this page on Dan's site for pricing, along with his comments about the "other" Canadian seller I mentioned: http://thetubestore.com/shuguangtreas.html
  • If you want contact info for the Chinese seller, please send me a PM with your home email address.

Thanks,

Neil
 
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nsgarch

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further to my previous post #14

I received an email this morning from a friend in Denmark who bought two quads of the KT88-Z's (for his two McIntosh MC275's) from the fellow in China (my edits/comments in blue ;--):

Hi Neil

My treasures have now runned 24 hours (hours not go so fast here in DK)
And WOW:

The soundstage is much bigger, more tight and deep bass, and voices have never sounded so good
Background is more silent and everything is more alive
Long time ago I tried to translate "shimmer" with Google and woordbooks, but newer find out what you mean; now I know
I had told him I thought what set the NOS Gold lions (and EAT's?) apart from all the other KT88's, was the sparkle and shimmer in their sound :)I would almost say these tubes are alive and has a soul

Really Neil, these Treasures are a BIG improvement here, maybe bigger than the 5751 and 12AT7 changes. Could also be cause, now the Sound is overall better. Some kind of synergi between all the tubes and amp. Now Shuguang should make a Treasure 5751 and 12AT7

I remember the jump from McIntosh EH KT88 to Pentas KT88SC as big, but not as big as from Penta to Treasure. These tubes are worth every Penny, long lasting or not

Thanks very very much, Neil for your help, and noncorrupted comments and knowledge, that convinced me to buy the tubes. Today is sunday, the day with the best elektricity and best sound (who say neurotic)

Shuguang Treasure KT88-Z, the biggest inventory (invention?) since GPS

Best regards

Christian​
 

MylesBAstor

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Interesting, thanks Neil!
 

XV-1

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The first issue to discuss is 6550 vs KT88. Let me state unequivocally that I am not a fan of 6550s as I believe the KT88 is simply a far more musical tube. 6550s have an inherent grain structure in the upper midrange that is rather characteristic of the tube style regardless of manufacturer.

Hmmm, We might beg to differ on this.

I much prefer the sound of 6550 tubes. I prefer 6550's in my cj prem8a monoblocks with teflon cap upgrade and my Macintosh MC2102 monoblock amps which come factory fitted with KT88's. the Mac KT88 tubes are no longer used and in a box.
I mainly use the Svetlana winged C 6550 tubes that cj use in their tube amps.

I am with Myles re the grain. I have found no grain in either my cj nor Macintosh amps. I find the treble sweeter and more releaxed with the 6550's. The KT88's seem to be a little more extended, but to my ears have a tendancy to be a bit bright in the upper frequencies.
 

nsgarch

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300 hour followup -- Shuguang Treasure Series KT88-Z

I have a friend Mark, in Austin, TX, with amazing hearing. And he has an amazing "audio memory" too. He's familiar with my system first hand, but still, he didn't even know I'd ordered new tubes, much less installed them, much less they'd only been burning for about 25 hours! I had no sooner picked up the phone one night, and Mark says, "What record is that?" I say, "It's the radio, why?" He says, "Wow, your system sounds really good!" -- over my crappy Panasonic cordless phone, apparently . . . . .

OK, well I had some issues with a couple tubes in that first quad I received, and the factory insisted I return the whole quad -- who am I to argue? -- it's not like I don't have tubes. When a hand-selected (by my dealer, at the factory) quad arrived 2 months later, they were equivalent (after 300 hours burn-in) in all test values to EAT's specs and to (really new) NOS British Gold Lions as well. We're talking transconductance values of 12,000 micromhos. By comparison my gently used quad of ANOS (almost new old stock ;--) Gold Lions read 10,500 +/-- micromhos.

When I did re-install the replacement set about 3+ weeks ago, I didn't say anything to anyone. One reason was by then, I'd come to realize Shuguang was quite serious about the 300 hour burn-in time (intitially, I thought it outrageous, but not now) and I just wanted to give them the benefit of the doubt, and not do any evaluating or testing until after that period. One night my Mark calls up and, I swear, the first thing out of his mouth is, "Oh, you got the new tubes"!? Now had he said something like " . . and the soundstage is better too!" I would have known he was pissing on my leg But no, he has great hearing, and you can pretty much believe anything he says about sonics! 'Course, he's 24 years my junior!!

Now about these tubes: first a disclaimer. I have only used the Treasure Series KT88-Z's, and only in my MC275. I have no idea how they would sound in other amps, or how other tubes in this series would perform. However, Shuguang has a long history with the KT88 tube (they also have a long history with some of the other tubes in this series.) Internally, the KT88-Z is physically different than any other KT88 I've seen. The plates are a bit shorter, black, and have the biggest, oval-shaped alignment holes I've ever seen -- three on each side of the plate. There are no side getters -- the carbon coating would prevent that; instead, there are two huge halo top getters. They also draw more power. My MC275 Mk IV draws about 195W at normal listening levels with most KT88's. With the KT88-Z's, it draws about 240W. Nevertheless, these tubes run extremely cool, but again, that's in a Mac.

I used to think NOS Gold Lion KT88's (and all the other NOS Genalex power tubes as well) had a special shimmer and sparkle that no other KT88's had (with the exception of the very expensive EAT's.) So I was pretty surprised when after about 80 hours, I had to admit that the Shuggies sounded better than my originals GL's. How? The best way to describe it I think, is the "size" of the presentation. They have the other attributes of NOS GL's (and EAT's?), plus an enormous soundstage, and a substance, or gravitas, to every sonic detail regardless of frequency. Now I know those sound like pretty wild claims, but (at last) I'm not the only one who thinks so, and consider this: Mark spotted the difference in ten seconds flat, on the telephone!! (He can hear things on the telephone I can't even hear in the flesh!)

These tubes are available in North America from a number of dealers: the TubeStore and GrantFidelity, both in Canada. GF is running a special on AgoN for $450, and TubeStore is about $525/quad incl. shipping, I think. In the US, Woo Audio in NY, and Pacific Valve in Chicago. GrantFidelity claims they "add value" by thoroughly testing all their Treasure Series tubes for various parameters that the factory does not. I might have bought that, except that Shuguang tests their 'non-Treasure' tubes for multiple parameters, so why not these? Simple: they can't! No manufacturer could spend the 280 (extra) hours these carbon-coated tubes require before any testing would be meaningful; and BTW, they do test all these different parameters at the factory, but only qualitatively. And I can tell you from my own experience with these TS tubes, most numbers will change over the 300 hour period. So unless GrantFidelity is actually burning in the tubes they sell for 300hours, their claims are without merit, IMO.

The Chinese seller I have worked with is already providing reliable service to the people I refer. (He does not sell on eBay.) His English, his prices, and his product are excellent: he charges $357 for a matched quad of Premium A KT88-Z's, which includes international PayPal fee and 3-day insured DHL airfreight. Hard to beat -- especially if you need eight or more tubes!! I spent a considerable amount of time with Clark so that he now understands the care and feeding of the neurotic O/C North American audiophile You can email him from his website www.goodcomponent.com and tell him I referred you, which will identify you as a bonafide nutcase! Make sure you specify you want Premium Grade--A tubes, a matched quad (you will get two matching matched pairs), and most important, that you want tubes with no less than 47mA plate current. 60mA is the max., mine are 57mA. You may have to wait for a new production run if you want the highest values, but anything over 50mA is terrific, so don't obsess over it!

Neil

N.B. -- I previously posted this report on the McIntosh forum at AudioAficionado; where you will also find some comments by my friend John (jprest) regarding his experiences comparing the Treasure Series KT88-Z's versus NOS Tung Sol solid blackplate 6550's. At first, he thought he liked the vintage 6550's a little better. Now he's not sure :D
 
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MylesBAstor

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Thanks for the interesting write up Neil! It's been years since played with the Genalex KT88s, at the time in my cj MV75A1. They were so much better than the Sylvania 6550s and later GE 6550s that cj supplied. So much more transparent, extended and musical. Same went for the KT77s in my friends Jadis JA-80! Only reason he got rid of the Jadis was that it just wasn't enough power for his Infinity RS1bs :(
 

markc2

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The KT88Z has (correction) two halo getters, both on top. The plates have three very large oval holes each side. Their internal structure is not like any other KT88 Shuguang makes. In North America, I recommend you purchase them from Dan at the TubeStore in Canada. You can purchase them from China also for a bit less.

Excluding the EAT's, which I admittedly didn't hear under optimal circumstances, my hands-down favorite, in my McIntosh MC275, and driven by GEC A2900/CV6091 (12AT7's) is turning out to be the new Shuguang Treasure Series KT88-Z. Here are some excerpts from a recent email exchange, which I hope will answer most questions:

Thank you for responding to my question on the TS KT-88's. It is comforting to know that Shuguang and Clark are doing their best to resolve the issues you identified with your KT-88's. Unfortunately, my tube tester does not allow me to perform the measurements that yours does. I usually measure my tubes when I receive them and take quarterly measurements to see if there are any changes to the measurements, as a means to determine tube life. Still wondering where to buy the tubes ($520.00 vs $350.00 from China). Also, I would like to hear from you how the new set of TS KT-88's measure up, when you get them.

I have about 175 hours on my (second) set of TS KT88's, and they already sound better than my NOS Gold Lions, which means they're as good as EAT's, (or maybe better?!) In fact, my friend Mark, who didn't know I'd received the new set, called this afternoon and hearing my system in the background, just casually remarked "Those Chinese tubes are really great!" just as he did with the first set -- only this time he knew it wasn't "the record"!) The boy has amazing hearing! I have no idea what the life of the TS's will be (and I bet Shuguang doesn't either!) but if they go 6000 hours, that would be pretty good. The NOS Gold Lion/GEC's went 10,000 hours and up! But these new carbon-coated tubes are an unknown quantity. They really do take 300 hours to burn--in. They don't take 300 hours to sound good; but their test values change (improve) as they burn-in, which is not typical of new power tubes which usually "settle down" after 20 hours or so. This is probably why the Shuguang factory only tests these new TS tubes for actual plate current (and not even under full load at that) and all the other values are only checked qualitatively. So who knows how long they'll last? ;--)) until they've been out in the field for awhile.


Thank you Neil, for the kind words. Must be all of those years working in a clean room environment. No dust to get in my ears ;)

Mark
 

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