New KT150 tubes?

Veerapaaneni ... I e mailed ARC about using the KT-150s in the current Ref line and whether the GS-150 (soon to be released) and the Ref 150 have different innards. So far, no answer.

Here's my cynical speculation. I think the GS-150 WILL sound better than the Ref 150 only because it uses the KT-150 tubes. Otherwise, until someone tells me that the GS-150 has different innards than the Ref 150, I think it's just a dressed up Ref 150 with KT-150 tubes.

I hope an ARC dealer or ARC service tech catches this thread and disabuses me of my cynical comments. I WANT to be wrong, so please someone disabuse me. But so far I see no rational reason for ARC continuing to be officially mum about dropping the KT-150s into their current Ref line. In the meantime, I wait.

BIF

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.