 
|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
|
|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
In Reply to: KT90 is mind blowing! Good heavens this tube rocks! posted by DevoX on November 07, 2002 at 17:53:14:
... but I am glad you did.As we know, not all tubes work best in all amps, and people hear different things going on but it's nice you found a good synergy in your amp with those tubes.
I remember my first ever visit to a tube factory was in early 1990 seeing the KT90's get born at the Ei factory. Cool stuff. (way cool in January in Yugo-land...)
Have fun!
Cheers, EveAnna Manley, Manley Labs
Follow Ups:
of this tube. Do you know if this is the case? I have always wondered about this.Thanks,
ja in clear and cool, Tucson, AZ
I was there at the factory twice in in January 1990, mid 1991, and DM went a third time without me.I was first in Nis the first week of January 1990 where they showed us the first prototypes of the KT90. There had been some correspondence between DM and the Ei factory for alomost a year before our visit as to what he wanted them to build. (See my post above regarding the KT90 NOT being based on the EL519.)
The actual engineering of the guts of tube was done primarily by the head Ei engineer, Blagomir Bukumira. We took home four samples and did the initial testing. Some suggestions were made and production began. This was the first "red" paint version. As with any first production run, of which we had to buy ALL of them, there were things to be improved upon.
The second version incorporated some structural modification suggestions from Bill Perkins. This was the "blue" version. You can see the additional spot welds for the concentric inner anode structure if you compare them. More meat. As I have previously posted, in 1993, tubes that fell outside our acceptable parameters were sold to a certain tube vendor who put on a prettier brown base and silk-screened their own "KT99" logo onto the glass.
Then the war started and the embargo went up and none of us could get tubes out of there. The factory also was having trouble getting raw materials IN. Contrary to rumours at the time, the Ei factory was NOT bombed, as we now know.
There later came a third version with wings outside the anode structure but gone was the additional inner plate structure needing all those spot welds.
The latest KT90's I have here, what I would call the 4th version, the sacrificial element tacked onto the anode structure that was square is now circular. Other than that, it looks like the version 3 tubes to my eye.
Here are some quick pictures I just put up for you.
KT90's I have known and loved...
As for bad blood, there was some disappointment as we were supposed to be the world exclusive distributors for the KT90 but this part of the contract was not ultimately honoured by the factory, although it was basically more or less enforced for two years. It was the "less" part of this equation that raised some concern. On the other side, it was understandable that other tube amp manufacturers were not happy to have to buy their tubes from a competitor in the tube amps biz who had been granted "exclusive rights for the whole world concerning advertising, sampling, and sale."I have faxes from Ei-RC from March 1991 outlining all of this. It is quite interesting stuff.
With this, with the war, with all the weirdness that went down, perhaps the factory's memories fall short in some areas, but I was there and I have the original correspondance needed to refresh my memories.
Cheers, EveAnna Manley, Manley Labs
I have always been curious about the response from the factory that I read some years ago about David Manley's involvement. I found it hard to believe that he was not engaged in the development as an interview with him had stated.Thank you again,
ja in Tucson, with the sun going down and a beautiful sunset, AZ
Manley Labs as a company only started in 1993...(You can read about the corporate history here since everyone seems perpetually confused about it.)
Credit where credit is due: it was David Manley who caused that tube to get born and more importantly funded that tube to get born. I was luckily there to witness all that.
It was a big deal at the time as there had not been a new output tube design created in many, many years. And do not forget back then, the Russian factories were still basically hiding behind the iron curtain, the chinese tubes of the time were generally flyweight, and well, it was getting kinda scary. The GE plant had already closed or was just about to (can't remember) and we all were almost faced with a severe tube crisis.
It took real vision, guts, and hundreds of thousands of dollars to make that tube happen, and for that, give credit where credit is due.
Cheers, EveAnna Manley, Manley Labs
they said that Manley had no involvement in the development of the tube. I had also read a number of times that David had helped with the development so I often have wondered why the factory would state this. It seemed like there was bad blood for some reason.Thank you for your response,
ja in partialy coudy, Tucson, AZ
This is one cool lady! I met her at the HT2002 in NYC and got to talk to her about audio. She's got real cool names for the company's audio gears. Many years ago before the invention of digital camera, I send her a 'Telefunken' EL34 for inspection and see if it was the genuine article. Thanks!
that the KT-90 was the standard output tube for all their power amps. That is until the embargo ended their import into this country. The word we got was that VTL (Vacuum Tube Logic) was keeping all remaming stock for themselves, since Mr. Manley was the one who had designed the tube and, as such had some control over who got what.
I do recall a high degree of stress at A.R.C. during this time, as an adequate substitute was sought out. Enter the Sovtek 6550. These tubes proved to be consistantly reliable and, more importantly were available in large quantities.
While no one at A.R.C. ever came right out and admitted (that I was aware of anyway) that the 6550 was not as good sounding as the KT90, you kind of got the feeling from the engineering department that this 6550 was sonically, the second place tube. Whatever the case it was vital, for the continued production of the tubed power amps, to have a steady source of output tubes.
I don't pay any attention to the activities at A.R.C. anymore but I'll bet if these new KT90's are as good as you say, it won't be long before they find their way back into the A.R.C. parts room.
The thing that makes me curious is if they really are out of production. I mean, I see lots of dealers on-line that claim to have this tube in stock. I bought mine from one of them without any problems. I believe Triode Electronics has "current production" Ei ECC83's in stock, and recently put the KT90 back to "in stock" status from what I can tell.Does anybody have the full scoop?
-- Robert
Who said KT-90s were out of production? Ei is still producing tubes, including the KT-90, 12AX7, etc. But for some reason this rumor seems to be out there, even the people at Magic Parts (Ruby) are/were saying the tube is out of production. Strange...There are some quality issues on the KT-90 right now, so the percentage of rejects is quite high; but the tubes are still being made AFAIK. My own stock of KT-90s is quite low, as I've had to reject 80% + of what I received lately. But a good one is a GREAT tube!
The Ei 12AX7 has been changed a number of times, so I believe what Ned's site is trying to tell you is that he has the latest design tube, which is the one in current production.
Also, as far as tube life, I can tell you I've had the original KT-90s in my Citation amp for 12 years - they are still great! I got a couple "red label" sets via David Manley way back in 1991, and then during the first embargo David was able to get Bill Perkins to send me some "blue labels" - just 4 is all I could get. I still have them, new unused sitting in my personal stash except for the set in my Citation.
Oh, I knew they were still producing tubes. But this rumor is out there, along with the one about NATO bombing their factory (ridiculous).As for the "current production" ECC83's, I see that they are now back to the grey plate design. I have last year's models with the chrome plates. Now I also see that they have the Ei "Elites", which I guess have gold plated pins and are specially selected at the factory or some such. I have some Ei 12AT7's that I use, as far as I can tell Ned is the only place to get them.
Have to keep feeding the need to upgrade, I guess! Grey plate, chrome plate, gold pins, rib plates, ticklers, etc. Crazy world.
-- Robert
Hi Robert,You wrote...
"As for the "current production" ECC83's, I see that they are now back to the grey plate design."
Correct you are, sir!
"I have last year's models with the chrome plates."
Yes, they made their appearance last year, and now apparently are history.
"Now I also see that they have the Ei "Elites", which I guess have gold plated pins and are specially selected at the factory or some such."
Actually, the worldwide distributor does the plating and screening. This is good though, as I was rejecting almost 40% of the regular Ei 12AX7s, the "Elite" reject rate is about 10%. Most "Elite" rejects are for microphonics (DESPITE the fact they are screened by the distributor) and for cracking in the glass in the tube base.
"I have some Ei 12AT7's that I use, as far as I can tell Ned is the only place to get them."
That may be, I don't stock them yet as my NOS supply is still okay. But certainly Ned's a good source (and a good guy!).
Hi Robert,You wrote...
"As for the "current production" ECC83's, I see that they are now back to the grey plate design."
Correct you are, sir!
"I have last year's models with the chrome plates."
Yes, they made their appearance last year, and now apparently are history.
"Now I also see that they have the Ei "Elites", which I guess have gold plated pins and are specially selected at the factory or some such."
Actually, the worldwide distributor does the plating and screening. This is good though, as I was rejecting almost 40% of the regular Ei 12AX7s, the "Elite" reject rate is about 10%. Most "Elite" rejects are for microphonics (DESPITE the fact they are screened by the distributor) and for cracking in the glass in the tube base.
"I have some Ei 12AT7's that I use, as far as I can tell Ned is the only place to get them."
That may be, I don't stock them yet as my NOS supply is still okay. But certainly Ned's a good source (and a good guy!).
Yes, the first design KT-90 had a problem running in the Manley circuit, though I don't recall why, nor what David Manley suggested as a fix to the manufacturer. It did work, though.The first design KT-90 works well in the Tube Research amps, without any problem. Great news for TRL owners, because the first design KT-90's sold for bargain basement prices after the redesigned second design.
on the set. One did go weak but I had a matched tube for a back up and the others tested about the same as the new one. I would like to try the version 3 that everyone talks about.ja somewhere in southern AZ.
I haven't used the First design KT-90 for quite some time, opting for KT-88 Gold Lions. What's the word on the 3rd version KT-90?
The third version is what I am raving about. I've heard a lot of stories about the history of this tube but the most common is that it was designed for a speicific few amps.I believe the new 3rd generation KT90 should work fine in an original KT90 amp design. I think the "fixes" really only change the tube slightly so that it will also work in a 6550/KT88 design (since the original KT90 was so close to begin with).
Either way, it's a spectacular tube. I am way impressed and sold "for life"...
-- Robert
This post is made possible by the generous support of people like you and our sponsors:
Top of Page ]
[ Contact Us ]
[ Support/Wish List ]
[ Copyright © 2025, Audio Asylum, all rights reserved ]
