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KT120 Tube compatibility w/ Jadis Defy 7 Amp MK 1

Hi, I have an original Jadis Defy I just acquired for I liked its sound very much. However, I don't have any users manual or schematic for the serial #445. Could anyone help by sending a .pdf or electronic copy.

Also, there is a new tube out for the KT88/6550/KT90/EL34 socket line called the KT120. It is the most powerful tube of all of them.

I would like to replace all of the current (12) 6550B tubes with the new larger KT-120 Tubes by Tung Sol (which has a plate dissipation of 60 watts, making it the most powerful tube in the 6550/KT88/KT90 family, or approximately 10 more watts/tube vs. KT90 . Also, when used at the parameters found in existing 6550/KT88/KT90 circuits, the Tung-Sol KT120 is impervious to overload, delivering peak power with extreme reliability and long tube life). Another note regarding universal replacement/compatibility is that the glass envelope of the KT-120 tube is 1/2" taller than other KT88 cousins to accommodate the larger internal plate structure and larger control grid cooling fins, which won't present a problem. However, a word of caution is given regarding the KT120's small increase in current vs. the next most powerful KT88 or KT90 (close in current draw), wherein they say the filament of this tube draws 1.7A to 1.95A, or 0.1 Amp to 0.35 Amp (100 to 350 mA) more current than a KT88 at 1.6 amp; so they say to be safe and recommended to check with your amp manufacturer to make sure the Jadis Defy 7 filament transformer will or can handle the increase in current (at 0.1 to 0 .35A/tube and if you have a quad that is 0.4-1.4A total additional current draw with normal current of 1.6A/tube) without any transformer mods. Will this small increase in current for the Jadis Defy 7 filament transformer be able to handle this increase draw in current required of the Tung-Sol JT120?

Any help answering this technical question would be greatly appreciated and I would gladly pay for a owners manual/schematic for this 100wpc push-pull configured amp design.
bradleys
hifigeek1
770 posts
 
Wise words Skip. I felt the same way in my previous post.
sdurrheim1
2 posts
 
Hi Skipweasel. I have purchased 2 Defy 7's to run Dali Megalines, one is a MkI the other a II. I am hoping to use the MkI to run the tops and the II the woofers. Could I ask you for a copy of the schematics? I would love them on file!!
calle_jr's avatar
calle_jr
5 posts
 
>Wiebe; Are the transformers in your JA80s setup for 6550 or KT today?
wiebe
7 posts
 
Hello Calle Jr. These are from 2005 with kt 90 from factory, here you can also set in 6550 without problems. After two weeks playing with the original kt 88 from Jadis, bias was too high, they burn out after 30 hours already, the Dutch importer has bias decreases but problem with all brands was 88 kt at 1500 hours is 50% lot and the rest is worn. The 120 kt is deployed without the bias is increased, is possible (this tube is much more power than a kt 90) And this is the most beautiful sound that my wife and I find we have ever received from a tube.
The transformer,s of the ja 80 are themselves less hot with the 120 kt, no matter what and how old the ja 80 is, the transformer is more than heavy enough for the 120 kt.
calle_jr's avatar
calle_jr
5 posts
 
Thanks a lot Wiebe. I tested the Jadis factory KT88 Gold Lion tubes and have the same experience as you. I have now connected the orange wire on the trafo for 6550-operation and changed for 6550 Winged C. It works good and sounds wonderful, but still, the JA80s eats some tubes. I will test the KT120.
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