Questions on KT150 tubes

Upscale Audio comes though …. kudos!!

This is an update to some old posts about sourcing KT-150s from third party tube vendors.  Just bought 2 quads of KT-150s from Upscale Audio.  I had several telephone conversations with Kevin Deal and a UA service tech about the tube matching challenges I experienced in the distant past with my ARC amp.

Kevin and the tech explained that UA is using a third testing device (an Amplitrex or something like that??) that is set to ARC amp operating parameters.  Extra care and time is taken with matching ARC amp tubes.
  
So I tested UA out by buying a matched pair of KT-150s.  First set, … ok.  The tube biases in the set were within 2 or 3 mVs, which is as good as ARC matched tubes.  Second set, … the same.   Excellent.

I bought a 3rd pair.  The bias delta was outside ARC spec.  Called Kevin.  He said that it is best to order KT-150s in matched quads. UA can do a better job matching that way.  So I did.  Kevin kindly took the 3rd set back and refunded my money, … promptly.

I got the quad last week.  I was and am stunned.  The tube pairs match as close as or better than ARC matched tubes.  So kudos to UA and Kevin Deal for making me a satisfied customer.  

BTW, UA increased its price a little for ARC matched tubes.  UA spends a lot of time with ARC tubes and I do not blame him.  The price increase is de minimis for what we get in return. Just be sure to let UA know about tube matching concerns in the comment section of the online order form. Based on my experience, I am confident UA will get it right. 

Bottom line:  kudos to Upscal Audio and compliments to Kevin Deal.

Just googeled  kt150;s. seems someone  with a  Conrad Johson rolled to KT150s with no issues at all.

Right now i had him bias for kt90's and sold those off, and now running kt88's with the same bias point as for the 90's.. I did not want to spend another $250 for rebiasing a  tube just a  hair fraction off from the previous tube,,now with the 150's, i can see the bias as practical vs the current  kt90 bias point. .


https://www.conradjohnsonowners.com/viewtopic.php?t=713

I am now on my second set of KT150's in my Jadis amps. I noticed that the newer batch seem much more powerful than the originals. Quite odd.
That, plus apparently there are very few tube testers out there that can actually test these tubes accurately. They need 600 volts + to test and most ( including several Amplitrex models) cannot supply enough voltage to test them. I am still checking around to see which models of tube testers can actually accurately test them. 
Also, the new Jadis models have specific transformers in them that allow for the KT150 tubes...if yours is an older model, I think transformer damage is likely with the new tubes. Mk 2 models are required of the Jadis gear.

Thanks for the post, . 
I have a  good local tech geek who can advise me about employing the kt150's.
as you know jadis builds high quality trans, i do not run hot volume anyway. 
I plan to purchase the 150's,. if they run hot,,,for whatever reason,,i 'll go back to 88's. 
that will be  a  late 2020 project. 
i'm not worried about damage to the trans, as i say i listen on low gain,, 

@mozartfan   I would say that you will probably run into trouble with your Defy7. The KT150's are not going to bias properly in that circuit, would be my guess. If you damage the transformers with that misuse, I also suspect that Jadis will not warrant them. Like decooney stated above, best to call the dealer/distributor for Jadis first. Remember that the KT150's need at least 600+ volts at the plate. The new Jadis designs, called the MK2's are designed by Jadis to utilize the KT150's...and need a slight mod to utilize the more traditional tubes....BUT the older designs were NOT designed to utilize the KT150's.