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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
hifigeek1
770 posts
 
I believe the pic on the web site is the G integrated amplifier.
bifwynne
2,206 posts
 
Here's some pics:

www DOT theaudiobeat.com/highend2014/highend2014_arc.htm

Gary, TAB says the new models "are 'reimagined' versions of current models." Do you know yet if the G series incorporates new or improved technology, other than the KT-150 tubes.

Just speculating of course, but if the G series is essentially repackaged existing products, the use of KT-150 tubes may permit one or both inferences (or surmises) that (1) the existing product line can handle the tubes and (2) that ARC completed "life testing."
hifigeek1
770 posts
 
I have no idea.. I will have more info after next weekend after the hi-fi show in Newport.
bifwynne
2,206 posts
 
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.
bifwynne
2,206 posts
 
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
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