2. amps-preamps
  3. 127957-80920

KT150 Tube Matching

Ok. Educate me. I don't know enough to even be dangerous. What are the critical factors used when matching a set of KT150 tubes, say, to go in an Audio Research amp? Transconductance? Bias current draw? A combination of the two? Is there any spec. or threshold on the variations? Does Audio Research do anything special to match their replacement tube sets? 
imgoodwithtools
wolf_garcia
6,613 posts
 
"thetubestore.com" has a wealth of info on what's important for tube matching.
jperry
2,430 posts
 
Buy the tubes from Audio Research
knghifi
1,668 posts
 
When shopping for power tubes (NOT NOS), I look for dealers with higher quality and larger supply of tubes for a better match. Upscale states they pay extra for tubes with higher micromhos.  ARC is 2x price of Upscale ... don't think you can go wrong with either. 
lostbears's avatar
lostbears
537 posts
 


 Tubes need to be burned in a bit before matching to get a close match. Otherwise they can drift apart as they burn in leading to a poor match. I believe Upscale does this. I know Jim McShane does. The last 2 quads of KT120s I got from him were dead on. Next to no drift. I did not have to adjust the bias again after the first check. 


More to discover