New KT150 tubes?


Has anyone any experience with these pretty new tubes. There are already one or 2 amps I know of, that use them. The review of one of these amps in a UK magazine suggested they were a little warmer and more natural sounding than the nearly new KT120's

The article also suggested they were a straight swap for KT120 based amps, with no adjustment necessary. They are more than twice the cost of KT120's, but still not too costly compared with NOS tubes. I know changing from KT88's or 90's to 120's. did require some amp modification. I have an ARC reference 75 and might want to try the new tubes at some point, ARC don't seem to have a customer E-mail service, to ask the question
david12
Regarding which of the ARC Reference amps would be most likely to accomodate the KT150, I did get some advice from a dealer in ARC about 9 months ago. The advice was the fewer the number of output tubes, the less likely there was to be a compatabilty problem. This means of course, that the Ref 75 I have, was the best candidate. This was NOT a go ahead to try it though.
Hi Bifwynne, Thanks for the response! I will be a little more patient then and will wait another month or two and hopefully someone will have more definite answers for me. It will be great if the 150's can be used!
Chances are that the 120 to 150 swap is not as big an issue with the ARC amps designed for the 120s as going to 120s in an amp originally designed for the 6550. The issue in my mind is the QA done by ARC on the tubes they sell and warranty. Putting 150s in w/o ARCs blessing imparts two risk factors, one that the circuitry will not handle the tube and two, that tube variation may contribute to failures due to potential incompatibility. It's all about how the individual accepts the risk/benefit ratio. On buying a used amp I would send it back to ARC for a tune up unless it was essentially new. Did that w/ my VT200 even though it was a pain.
07-04-14: Xumbug
I have a pair of Ref 210 that have been upgraded to the KT120 with full resistor replacement by AR. My problem is: The tubes now have 2300hrs on them and I might need to swop them out. Do you think I can put the KT150 in them?
Xumbug (Answers | This Thread)
Yes, Go for it!
Hi joecasey,

You say that with conviction. Are you confident that there will not be any issue's? Would love to know what the difference in sound quality will be!