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JADIS JA80 with 6550 or KT 88 or KT90 ?

My Jadis JA80 was built in April 1999 and came equiped from the factory with eight 6550 valves.

Before deciding to buy a new set of tubes, I would like to know some opinions about the advantage or inconvenience of using the KT 88 or the KT 90 tubes in my JA80.

Is there any experience of using these tubes (KT 88 or KT 90) in an amplifier designed from the factory to work with 6550 tubes?

Many thanks for your cooperation.
rato456
kjgp
13 posts
 
Bump this one back to the top, looking for an answer to valve inter changeability.
szutinglee
91 posts
 
from Jadis via email:
"JA30 is an autobias amplifier, it does not need any adjustment when you change tubes.
Kind regards,
JADIS Service Commercial / Sales Department
Chemin du Pech
11800 VILLEDUBERT. FRANCE
www.jadis-electronics.com
Tel : + (33) 4.68.78.63.30
Fax : + (33) 4.68.78.85.15"
bartokfan
664 posts
 
The KT88's just arrived, replaced the KT90's with the Elecrto KT88's and after only 10 minutes of listening, promptly placed them back in their boxes. I'd say the quality lost is near 50%. In fact had the original JOR came with these 88's I'd be one very un-happy camper.
Dumb me, doubting the french.
loss in all three fq's in the 88's.
hopefully my seller will take them back with some discount of course,.if not I;'ll put them up for sale here.
Paul
trelja
3,223 posts
 
Paul, whenever you retube an amplifier, this happens.

Put the tubes back in, and let them run in for at least 25 hours. They'll open up. Trust me. It's called break in.

Now, I'm not the biggest fan of EH KT88 or 6550, and you may end up preferring the Ei KT90. But, whatever you use when you retube, even if they're Ei KT90, when you first power them up, they're going to be EXTREMELY constricted sounding, especially at the frequency extremes, and lacking in power big time.

Personally, I like the JJ tubes the best. But, interestingly enough, I have also arrived at the conclusion that the Chinese tubes being produced today are far better than anyone would expect. I would have never believed this if someone told me, but I've tried some small signal tubes recently that surpassed some extremely well regarded NOS varieties. But, even they needed a day or two to open up to the point where I was satisfied with them. For my money, I'm hoping I never have to buy another Russian tube.
bartokfan
664 posts
 
The 90's sounded excellent in the first minute.
Sound EXACTLY the same as today.
What I want to know is, does the other Jadis amps that use the 88 have simulairty as the EH88? If so then I may want to ignore the Cayin A88 and other Jadis' that use the 88.
Seems that most all Jadis uses 88's now.
Can the DA30 accept KT90's?
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