New KT150 tubes?

If one is willing to accept the responsibility (i.e. cost) for any problems that ARC deems due to use of an unauthorized tube then it is a no brainer. The problem arises when customers believe the manufacturer should assume that responsibility.

Djcxxx .... one other issue comes to mind. I'm thinking about resale issues. If I was interested in buying a preowned ARC amp, I would ask the owner if he rolled the KT-150s. All things being equal, if I could buy the same model, sans KT-150, I likely would. Having said that, this concern would be moot the moment ARC officially approves the use of the KT-150.

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 .... as a general matter, I would be remiss to advise fellow ARC owners to drop KT-150s into their amps unless ARC said it was ok. Much of the discussion in this thread pertains to dropping KT-150s into current vintage ARC Ref amps, namely the Ref 75, 150 and 250. These amps were specifically designed to handle the KT-120s. The design changes included a beefed up power transformer and power supply.

Admittedly the predecessor Ref amps (namely the Ref 110 and 210) are able to handle the KT-120s. However, as reluctant as I would be to drop the KT-150s into the current Ref amps (such as my Ref 150) until ARC sprinkles pixie dust on the tube, I would be even more circumspect about the earlier version Ref amps.

My thought process is that these earlier amps may not have sufficient power supply head room to handle the additional demands of the KT-150s. And that doesn't even speak to whether the KT-150s are compatible with the older circuit designs.

Just my humble opinion.

I get that you are ready for new tubes since you have 2300 hours on your KT-120s. And those pups are ripe to the point of rotten. I sure wish ARC would fish or cut bait already.

And since poor Kal and Chris at ARC have been pummeled with a million calls about the KT-150s, I'm afraid they will confiscate my amp if they suspect I directed anyone else call them. LOL :)

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.