New KT150 tubes?

Gary, my non-tech instinct (surmise) is that the KT-150 should be a drop in option for ARC's current Ref series amps (75, 150, 250 and 750). I base this conjecture on the following facts: (1) the KT-150 plate draw is just a few milli-amps more than the KT-120; and (2) the KT-150 plate impedance is very close to the KT-120.

In the former case, I would be surprised to learn that the current Ref amps already beefed up power tranny couldn't handle the slight power draw increase. In the second case, if the KT-120 and 150 tube impedances are in the same neighborhood, I would think that the output tranny should do a good job with impedance matching.

If my recollection of the facts is correct, I am puzzled why the KT-150 isn't a non-brainer tube rolling option. I'll double check the KT-120 and 150 specs and report back if my recollection is faulty.

I wonder if ARC's reluctance to "sprinkle holy water" on the KT-150 has anything to do with the pending 2014 introduction of the new G series gear, which apparently will use the KT-150. Well .... as I have written before, I trust ARC and will not drop in the KT-150s until ARC blesses the new tube. I have too much invested in my gear to impulsively drop a component into my Ref 150 until ARC says its ok.

Gary ... I don't like to guess or talk about stuff above my pay grade. So, I checked the New Sensor web site and copied the following specs:

KT-120

Plate resistance - 3000 ohms
Heater characteristics - 1.70 to 1.95 A
Plate current – 135 to 165 mA
Plate dissipation – 60 watts

KT-150

Plate resistance - 3000 ohms
Heater characteristics - 1.70 to 2.00 A
Plate current – 150 to 180 mA
Plate dissipation – 70 watts

I really don't know if the increase in plate dissipation current or plate current draw is electrically significant. Perhaps you can weigh in. However, to the extent that plate resistance is an important spec, the two tubes share the same stat.

Regards,

BIF

I don't have an answer for you. I will have to differ to ARC and wait, but I am getting impatient. I will ask again next week.

I was at The Show in Newport Beach this weekend and walked into the Alon Speakers room hosted by their designer Carl Marchisotto. Low and behold he was running a ARC Ref 75 with KT150's in it. He said, and these were his words, the differences between the KT120's and the KT150's "were transformative." No other room at the show including ARC dealers, were running KT150's. I did not ask Carl where he got the KT150's from or if ARC was a co- sponsor of his room. The plot thickens.

No...we need to wait...when 120s were thought to possibly be a threat to mankind itself and reported amp issues relative to higher heater demands were exactly zero...zero...we were cautious and...well...uh...nevermind.