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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
wolf_garcia
6,644 posts
 
One bit of hype that seems silly is the claim that the pickle shape eliminates microphonics...assuming this shape doesn't allow vibration from anywhere to get to the tube...nonesense.
bifwynne
2,206 posts
 
More importantly ... do the KT-150s sound better than the KT-120s and if so how much better. Even more important, how much do they cost and is the cost increase worth it.
tsushima1
1,165 posts
 
Bifwynne, Whilst not the sharpest of images when blown up I am pretty confident that they are indeed sporting the Mythical KT150! whether the circuit has been modified in any way is of course unknown.

I am aware of at least two intrepid ARC owners currently running KT150's in their 2x output valve per chanel VSi75's, bias set at 65mv , with no ill effect(as yet)noted.

Again one might theorize that ARC R&D may be a little more confident in respect of KT150 loading on the Mains transformer(s)as supplied on certain of their recent models, they may however be a little less comfortable ,as yet ,in respect of Mains headroom on other models , in particular were a Single Mains transformer is already supplying a Quad of 6550's or KT120's per channel .

Life testing of a new production valve and thorough evaluation of any potential implementation within existent models may take a reassuringly great deal of time .

Mere speculation on my part of course ,In which , as an Ref150 owner I would very much like to be proven wrong !
wolf_garcia
6,644 posts
 
A great deal of time? How about listening to the amp to see how the tubes sound...that takes about 3 minutes.
bifwynne
2,206 posts
 
Wolf, are you mixing and matching thoughts. I think Tsushima's comment refers to life testing the KT-150, not so much the sound.

Just my own lay reaction is that from what I've read, the KT-150 doesn't draw a heck of a lot more current than the KT-120s. My knee jerk thought is that the KT-150s would NOT damage the power trannies.

Further, the KT-150's power output is not that much greater than the KT-120s. Again, my knee jerk reaction is that the KT-150s wouldn't harm the downstream components in the gain stage.

But ... hey, I'm not a EE. So, like the rest of us, I'll patiently wait. I love my Ref 150. Dam* if I'll stick a tube into it that ARC doesn't bless.
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