Does anybody know the significance of the Magnoval brand of Ei KT90s?
Does this box provide any insight into which series of Ei KT90s these are?
Does this box provide any insight into which series of Ei KT90s these are?
Ron’s New System
- Thread starter Ron Resnick
- Start date
Magnoval is just a name for European socket type of tube. don't worry, everything is fine
I found on an old website the following interesting history on the Ei KT90 shared by EveAnna Manley:
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
----
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
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
----
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
Ron, this document penned by EveAnna Manley is well known and refers to the design modifications to the second production run as per my post a little earlier , whilst this revision has become known to as Series II and generic to all production from that time onwards the “Blue“ revision that she refers to merely being the stencilling applied to the valves destined for shipping to Manley.
You may strike gold and find NOS or used Manley ‘Blue” stock exactly as so, however they remain Nis factory Series II manufacture several hundreds being marked simply as Ei in white , as well as many re- branded for other customers , please see previous images of such.
Unfortunately I am not in a position to evaluate myself the numerous additional welds inside the tube which signify a Type 2 tube.
buy the ei kt 90 from tubes.rs in(belgrade) my ebay link
I think he has the entire inventory from nis in his possession
www.store.tubes.rs
I think he has the entire inventory from nis in his possession
tubes.rs online store
TUBES.RS | The finest NOS Tubes & Tube amps - More than 350000 NOS tubes in stock and tons of vintage parts for Hi End audio
www.store.tubes.rs
His tubes do not have the spot wells on the plates and appear to have the extra “wings” that EveAnna mentions. I would say type 3.
All “type2” have the spot welds no matter if blue label VTL, , white label EI or gold label Gold Aero KT99, although EveAnna describes the latter as tubes VTL did not accept
This Ei KT90 thing is too much of a morass. I think new production KR Audio KT88s might be the answer.
KT 90 tubes are going to be a real tough go in terms of finding them-especially in NA.
Great tubes , I have 2 quads left. I use them in the CItation II mine are Type II rebranded Edicron- a reseller- but are definitely Ei. I acquired 4 quads 25 years ago. The tube is not good enough to pay $1200/quad imo. Very tough tube though YMMV
Also shown are my Genelex KT88 ( superior to the Ei but more impossible to find) , Genelex Kt66 I got tons of these "thrown in" testing new while I was in my Quad amp phase-excellent tube, Siemens slim bottle E34 I have maybe 2 dozen before they went crazy- very good tube, Mullard xf3, Mullard Xf2, Philips el34 metal base - I only have 3 NOS if only I could find a 4th! finally a Japanese Toshiba EL34 wihich is actually an excellent tube.
Mullards, I use in the Io and over the course of 20 years I am dwindling on quads of those now but have enough for the next 5 -6 years.
These tubes are getting increasingly difficult to find and the one's that were on the periphery years ago are now all of a sudden top of the list.
Great tubes , I have 2 quads left. I use them in the CItation II mine are Type II rebranded Edicron- a reseller- but are definitely Ei. I acquired 4 quads 25 years ago. The tube is not good enough to pay $1200/quad imo. Very tough tube though YMMV
Also shown are my Genelex KT88 ( superior to the Ei but more impossible to find) , Genelex Kt66 I got tons of these "thrown in" testing new while I was in my Quad amp phase-excellent tube, Siemens slim bottle E34 I have maybe 2 dozen before they went crazy- very good tube, Mullard xf3, Mullard Xf2, Philips el34 metal base - I only have 3 NOS if only I could find a 4th! finally a Japanese Toshiba EL34 wihich is actually an excellent tube.
Mullards, I use in the Io and over the course of 20 years I am dwindling on quads of those now but have enough for the next 5 -6 years.
These tubes are getting increasingly difficult to find and the one's that were on the periphery years ago are now all of a sudden top of the list.
Attachments
Thanks Ron , the dB level sounds normal and nothing unusual for such a large format system, with sufficient amplification!
The KR KT88 were the best KT88 I had on my Audiopax. I tried the Gold Lion, PSVANE, and EAT. This one exceptional, but I lost many of them.
The KR sounds great and lasts years.
I didn’t know that KR made a KT88. Now I have to try them.
Ron another option in the NOS space is the GE6550. I have never tried them myself but they have a reasonably good reputation. There is a fellow on Audio Asylum (JSTRM) selling new in box mid 1980s Jan GE 6550 for many years. I believe he got them when he left military service. Relatively cheap as well (I believe $650 for a quad). He states in his ad that he matches his tubes for current on a custom burn in rack. Might be worth a try.
I wouldn’t bother with Tung Sol 6550, I have tried to collect them for two decades and all the ones I find are burnt out (most from guitar use). Same with GEC KT88. I have had much better luck with GEC KT66 but if you need two matched quads for the auto bias Jadis amps that will be a tall order to find. You can pick up two quads of GL Russian KT66 for under $600 at thetubestore or other locations in the US and you might like them. If you don’t want to buy tubes made in Russia I can’t blame you, I got mine long before the war.
I may have a lead for you for you for new EI type 2 KT90s from a fellow I got some quads from a decade ago but it is a long shot. I will PM you in the next few days.
I am not a fan of 6550. Even in the Siegfried IIs I went with KT88s.
Thank you!
I think we're going around in circles. A KT 88 runs 450volts 55-60mA very well. A kt 90 requires more than 450volt/80mA, which significantly reduces the distortion. A current adjustment is necessary otherwise you will be disappointed with the tubes. my opinion.
I would rather try first out a cheap eh kt90 to see if it works in the amplifier.
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My JA100s have EH KT90s presently, and I love the sound. I'm just trying to gild the lily.
I love the sound so much I am reluctant to switch the transformer strap to the ostensibly proper 4/8 ohms setting lest I like the sound less than I do now.
I love the sound so much I am reluctant to switch the transformer strap to the ostensibly proper 4/8 ohms setting lest I like the sound less than I do now.
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