[Cyberslacker]

i have a Jadis intergrated and it has EL 34s they are
getting older so im thinking of switching to KT 88s.

i like em in the other amps i have owned and own,
anybody tried em in a Jadis ????

[Patrick Turner]

CyberSlacker wrote:

i have a Jadis intergrated and it has EL 34s they are
getting older so im thinking of switching to KT 88s.

i like em in the other amps i have owned and own,
anybody tried em in a Jadis ????

Should be OK.

BUT, and there is always a but, make sure the PT won't fry
when connected to KT88, because KT88 draw slightly more filiment
current, 1.8A instead of EL34 1.6A.
On the other hand, KT90 have less Ih than KT88, so are OK in this
regard.

Biasing will be different for the idle anode current with KT88.

So make sure that idle current for KT88, KT90, or whatever, is the same
as it was for EL34 which may mean replacing the Rk cathode bias
resistors or
re-setting the adjustable "fixed" bias.
Stabilty with NFB should remain unaffected, and should be unconditional,
but should be checked by a knowledgeable tech if you don't have a clue
about such things!


Patrick Turner.

[wb[_2_]]

CyberSlacker wrote:
i have a Jadis intergrated and it has EL 34s they are
getting older so im thinking of switching to KT 88s.

i like em in the other amps i have owned and own,
anybody tried em in a Jadis ????


Hi,
I serviced a big Jadis amp a couple months ago which employed six
6550's in each channel.
The amp was very powerful, and with matched sextets of Svetlana 6550's
in place, the thing sounded amazing. The few KT88's I have used seemed
to have a slightly warmer sound then the 6550. Are you sure your Jadis
is set up such that you can swap in KT88's in place of the EL34s? They
do bias slightly differently. The Jadis I worked on had 12 bias
adjustment pots on the main circuit board. I'd imagine that one could
have been adjusted for either the EL34 or KT88. The plate voltage was
well within the range of either tube.
The big question is if your Jadis' power transformer and output
transformers are up to the increased plate current usually found when
using the KT88 or 6550. Check your owner's manual or contact Jadis via
the web to verify that you can in fact use the 6550 or KT88. The KT88 is
NOT a direct replacement for an EL34. You are lucky, Jadis as well as
Aero Audio make really nice sounding amps that use really top quality
transformers. Whenever I service one, I like to take my time testing it!
Beautiful amps. Heavy as a 55 Buick Roadmaster! They just plain have the
look, feel, and sound of quality. Every problem I have encountered with
either a Jadis or Aero Audio was the result of tired or defective tubes.
Generally a resistor or bridge rectifier takes the heat when there is a
shorted tube. I have yet to see a transformer failure or a capacitor
failure in one of these amps.

Bill