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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
mozartfan
2,143 posts
 
Heard back from my friend at Jadis.

KT120 tubes present no problem at all in the Defy DA7. Only rebiasing is necessary.


^^^^^^^^^^^^^^^
Jadis is a bit slow in respose, but 100% they will get back to your Q.
My hunch was the 120's can be employed in the Defy,
The trans are built like tanks.
From what i've read on the Unet, the 120's are a  superior sound QUOTE: <<in all departments>>>
, Just bought the 88's. 
I over loked cking out the 120;'s. 
Oh well that project will have to hold off, as my Defy is at Richard's shop, having all resistors swaped out  for Takman Rey's,. Its like 50 Rey's and a  pair of REX/carbon 18k's. 
Takman does not stock metal in the 18k so had to go Carbon Film/Rex.
Will post YT vid in 3 weeks after upgrade is complete. 
120's later next year. 
mozartfan
2,143 posts
 
I've got a Defy 7 Mkl with 6550's. I wanted to try KT88's but was warned by a Jadis dealer, it's risky on the trans...


^^^^^^^^
6550 = kt88, 2 labels/same tube. and yes Trejla alrady got word from Jadis Defy accepts 120, which is not any surprise to me. 
I have no issues with these Svet 6550's. Just that I am looking fora  more wider sound stage,  for my classical muisc,,I am betting the 120's deliver that superior width and fullness.
If only by a  hair thin margin. 
Honestly 
88 vs 90 vs 120, we are only talking  minimal shades of comparison. 
Yet  our search for a  new tweak drives us to try various sets. 
I can say for sure, all 88's do not sound the same.
I found the Svet 6550's a  superior sound vs the well respected, highly acclaimed Gold Lion 88's.
I've read another comment (audiokarma)supporting my opinion. 
And from  a  ebayer, << SEvet 88's  matched the GE NOS 88's>> so lets put that <<GE's 6550s best ever 88>> to rest. 
 Furthermore, again taking the OP way off topic, the NOS Svet 6550's (which i sold off cheap 2 yrs ago) are identical to the new Svet 6550's, Exactly identical tube, <<The NOS Svet 6550,,blah blah>> myth is busted , laid to rest. 
mozartfan
2,143 posts
 
Richard explained with EDU/science why the Defy will not like running  kt120's, Best stay with 6550/kt88.

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