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Electro Harmonix KT90?

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#41
fdegrove said:
Yes, I know Mike too and the Russian KT90s will tell you that it's a EL519 resocketed once again, improved on earlier versions or not.
Click to expand...

Another voice... i mailed Bill Perkins for a comment and Bill says:

While I certainly have MUCH to say on this topic, it being I am the one who fixed the KT90's problematic screen/anode geometry, did a ** complete ** set of working drawings for the part (still on file here BTW) and sold both David Manley and Roger Modjesky the Tek 570 Curve Tracers they now use, the matter of lengthy comment on the forum will have to wait until after after Xmas.

I will however say right now that punters, arm chair engineers and proselytizers notwithstanding the KT90 is NOT a re-based anything. It is what is, which is to say it's the KT90/A/B . . . period.
Click to expand...

dave
 
#42
Hi,

While I certainly have MUCH to say on this topic, it being I am the one who fixed the KT90's problematic screen/anode geometry, did a ** complete ** set of working drawings for the part (still on file here BTW) and sold both David Manley and Roger Modjesky the Tek 570 Curve Tracers they now use, the matter of lengthy comment on the forum will have to wait until after after Xmas.
Click to expand...

This is version #2 right? Not #1.

Would you believe me if I told you there's no economy to be found in developping a new tube type anno 1990?

My point is that the basic idea was, hey...What about this EL519? What if we kick an octal socke under its feet, we'd loose the top cap and magnoval socket and hey, if we're lucky we end up with something able to dissipate more power than the KT88...

Whatever happened I was in the tube dealer business when this tube saw life but I'm not that naieve to believe that a bit of chest beating of one company is going to yield this tube nobody's been waiting for other than those with soso KT88s...

There was a reason for this investment, the reason was the incredible crappy quality of the Chinese KT88s, that and nothing else was the kicker...
Not that the KT90 was a success, war and economical factors killed it straight away and it's taken people ten years to go back to 6550s and KT88 after the last decent ones were gone and I don't mean the MPD and REL ripp offs either.

Note also that so far no one claims what I said all along: the EL519 was the father of the KT 90 and still is to this day.
Anything else is a violation of history, believe me.


Cheers,😉
 
#43
They`ve arrived all 10 intact,

Wow are they built.

Big and heavy.

Guess what Frank, NO TOP DIMPLE, they are buit differently to EI`s KT90 explain that one Frank?

NEED HELP POSTING PHOTO


They look fantastic, i`ll put them in in place of my latest version matched Red Label KT88 Sovteks and see what they do, i have push pull triode mono`s 4 xkt88 per channel and built by my self no expense spared. Can some one put up their hand for me to email the photo i`ve taken of these new EH KT90`s as i have no idea how to post a photo, and they can post it up in this thread.
Cheers George.
 
#44
Hi,

Guess what Frank, NO TOP DIMPLE, they are buit differently to EI`s KT90 explain that one Frank?
Click to expand...

What's to explain? They're probably USSR EL519 reworks as I told you before.

Do you really think I haven't seen those already? Come on...

And for what it's worth, I never mentioned a top dimple anywhere anyway or did I?....Not that I mind a dimple in the right place, mind you...

NEED HELP POSTING PHOTO
Click to expand...

Nor not really counting on daddy Frank for that, are you?:whazzat:

Just e-mail me George, I'll reply, upon which you send the piccies and rest assured I'll post them in this thread...

Merry X-mass,😉
 
#48
O.K. fist impressions, are that straight out of the box they are better that the KT88`s, more inner detail and more grunt behind the transients, the top end seems just as sweet as the KT88`s and their not run in yet. Every thing was set up the same, bias re-adjusted, and to make sure i had a look on the scope and checked stablity under capacitive loads and h/f bandwith and l/f cutoffs all were exactly the same before i started listening.
I`ll give you an update after 200hrs use.

Merry Xmas to all, George

P.S. Frank did email me, and i have sent the pictures of these new beauties, he should be posting them up shortly, if not it`s up to someone else to email me.
 
#49
Hi,

Don't worry, George I'm an integer person.

The pic you mailed is way too big sizewise to post here so let me figure out some way to post it...

When acceptable in size to the forum I will post the USSR reply to the KT90😉

Nobody would attempt this at 6.00 AM but me, believe me....

Thanks,😉
 
#52
EH KT90EH
 

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#55
I just noticed somthing, they`ve got made in Russia on them.
They still sound good, all holding the bias well, i`ve only done about 3hrs so far because of the Xmas commitments, i should be able to realy start hammering them in the new year, one thing i can definately say is they run at half the temperature of the KT88`s. This leads me to think they could last a very long time as you can almost put your fingers on the valve, they are that cool, and they are suuposed to have the same heater current draw as the KT88, maybe because, they are that big they can get rid of the heat more efficently, and so run cooler?

Cheers George
 
#57
I`ve found out a little more of these EH KT90`s, from an anonymous source, that they are new version (2003) made in St Petersburg in the old Svetlana factory which is now owned by Electro Harmonix apparently.
I`ve been getting many emails about this new tube, but it`s history is very slow on comming forth. as i get it i`ll let you know.
Cheers george
 
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