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
I have heard from a number of people using KT150's in their ARC reference 75. The only problem is that the tube is taller, so the top of the amp can not be refitted. This does not apply to the 150 or other amps in the ARC line. I have ordered a quad from Upscale and will report the results, assuming the house does'nt burn down wnen the amp catches fire.

I am with BIF, I am sure ARC's silence is connected to the new amps fitted with KT150's. They want us to go out and buy their new shiny amps.
Whilst I, And for the most part, concur, with David and Bif regarding this Conspiracy Of Silence from ARC Central, especially in respect of the models sporting a Single Mains/Quad Output ratio, I am a tad less optimistic for the ratio as sported on the Ref150. Although this ratio may still prove safe and workable, within the performance envelope of the KT150 /REF150, under a marginally altered bias setting for the Master tubes ?!?!?
Well the KT150's have landed and are in my Reference 75. No sparks, explosions or other calamity, oh and they sound pretty good too. Right off the bat, I would describe a tight deep base and a deeper soundstage as initial, favourable impressions.

As Tsushima1 indicates, this is only feedback for the 75, not the 150 or other ARC amps using more than 4 tubes. I am using the same bias as the KT120's.
David12 and Tsushima ... I took a close look at the specs for the KT-120 and KT-150. Take what I say with a grain of salt because I am not a techie, but the current draw, plate dissipation and impedance specs of the two tube types are very similar. I surmise that any additional power demands that the KT-150 would place on the power transformer and other relevant passives would not be significant.

And I continue to wait.

P.S. to David -- how close was the "slave" tube's bias spec to the "set" tube's 65 mV bias number? I ask because for some reason that I cannot explain, IME, the delta between Upscale sourced KT-120 "set" tubes and "slave" tubes specs can be as much as 5+ to 8 mVs??? Not so with ARC matched tubes.
Gary (Hifigeek1) ... still no official word from ARC yet about dropping the KT-150s into its "standard" current Ref amps???? Has the new G series gear hit the stores yet???

In a private message from Kal a while back, he mentioned that the GS-150 is the best sounding amp ARC that has made to date. He did not answer my question about how the innards of the GS-150 changed from the Ref-150. On paper, they spec identically.