Does anyone have experience with the KT90 ?
How do they compare sonically with KT88
and 6550? Is there current production?

Iain

in article , Iain M Churches at
wrote on 9/15/05 7:31 AM:

Does anyone have experience with the KT90 ?
How do they compare sonically with KT88
and 6550? Is there current production?

Iain


Jim McShane has a lot of experience with KT-90s.

I have a quad of them that I plan to install in a HK Citation II when I
complete rebuilding it.

McShane says that they are sonically superior to the KT-88 in the Citation
application.

AFAIK they are still being produced in Yugoslavia. But apparently the
company making them has produced "good ones" and "bad ones".

I suggest you contact Jim for more info.

Jon

Iain M Churches wrote...

Does anyone have experience with the KT90 ?
How do they compare sonically with KT88
and 6550? Is there current production?

Iain,

Check my tube page on my site. The KT90 Ei is
a great tube when it's made right, but sadly
the current production has problems. The EH
(not a typo, EH) is blah.

FWIW, I sold my quad of GEC KT-88s after
I got my first KT-90 Eis. I never regretted it.

Drop me a note if you need more than what's
on my site.

Jim McShane
Need Tubes? Got a H-K Citation (Pre) Amp?
Check http://pages.prodigy.net/jimmcshane
Repro knobs for Citation gear in stock!

"Jim McShane" wrote in message
.. .
Iain M Churches wrote...

Does anyone have experience with the KT90 ?
How do they compare sonically with KT88
and 6550? Is there current production?

Iain,

Check my tube page on my site. The KT90 Ei is
a great tube when it's made right, but sadly
the current production has problems. The EH
(not a typo, EH) is blah.

FWIW, I sold my quad of GEC KT-88s after
I got my first KT-90 Eis. I never regretted it.

Drop me a note if you need more than what's
on my site.

Jim McShane


Hi Jim,

I have been asked to look out for some KT90s
for a small batch of 50W amps currently being
built.

I had the feeling that Svetlana made them too
but apparently not. (Their EL34 is exceptionally
good, and of very consistent quality)

Excellent website:-)

Iain

Iain M Churches wrote:

Does anyone have experience with the KT90 ?

Yes, KT90EH seem ok.


How do they compare sonically with KT88
and 6550? Is there current production?

More percieved bass definition.

Otherwise not much difference imho.
More brute force.

Patrick Turner.



Iain

Iain M Churches wrote:

"Jim McShane" wrote in message
.. .
Iain M Churches wrote...

Does anyone have experience with the KT90 ?
How do they compare sonically with KT88
and 6550? Is there current production?

Iain,

Check my tube page on my site. The KT90 Ei is
a great tube when it's made right, but sadly
the current production has problems. The EH
(not a typo, EH) is blah.

FWIW, I sold my quad of GEC KT-88s after
I got my first KT-90 Eis. I never regretted it.

Drop me a note if you need more than what's
on my site.

Jim McShane

Hi Jim,

I have been asked to look out for some KT90s
for a small batch of 50W amps currently being
built.

I had the feeling that Svetlana made them too
but apparently not. (Their EL34 is exceptionally
good, and of very consistent quality)

Excellent website:-)

One can get 40 watts class AB with a pair of KT90 in triode.

I have tried a pair in a Quad II amp which is ok because
they fit OK, and have 1.6A of heater current, same as KT66.
But ONE KT90 is like TWO KT66,
so you get about 25% more power in an Quad amp
using the same idle current as the KT66.
The limiting factor is anode voltage swing and the crummy Quad II OPT.
But Ro is also about 2/3 the KT66 case.
They are no harder to drive than KT66, KT88 etc.

I prefer the KT90EH to the Ei, the EH is like a new type of tube;
the internals looks like the anode is simply 10mm taller than in the
KT88/6550EH
which as far as I know are exactly the same internally.

The extra 10mm of metal means the plate dissipation is better.
The KT90EH could be allowed to idle at 35 watts.

Having 550V on the anode and screen is also OK for triode and UL.

Patrick Turner.



Iain

I use them in my Citation II, they sound great.

Frank

Jim McShane wrote:

Iain,

Check my tube page on my site. The KT90 Ei is
a great tube when it's made right, but sadly
the current production has problems. The EH
(not a typo, EH) is blah.
Drop me a note if you need more than what's
on my site.
!


Hello,
How can one tell the difference between the Type I, II, and III Ei
KT-90 tubes? Are there markings, writing, structure differences? Can
somebody post pictures?
Thanks, Daniel