2. amps-preamps
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Retubing an ARC VT100 mkll

Thinking of tube rolling my VT100 mkll. Currently using EH for both the 6922 input and 6550 output tubes. Less than 800 hours on the entire set, so its not that I need an entire retube, just looking to improve the sound if possible. What would give the biggest improvement, changing out the input or output tubes to KT88/90? Bear in mind I would need a closely matched OCTECT of either so bizarre/rare vintage tubes are out of the question. Thinking of Gold Lions or similar, any thoughts from the scholars?
spinaker01
hifigeek1
770 posts
 
Awesome. Well they don't keep me in the loop. So the issue isn't whether the amp can handle the increased heater current because it can, the issue is the fact that the tubes are mounted horizontally. Because the KT-120 is longer and heavier, there is a risk of tube sockets loosening up to the point where the tube looses contact with the socket and the tube arcs. That is basically the issue. That is why ARC does not support the use of KT-120's in that amp. BTW it does sound very good with KT-120's.
spinaker01 OP
491 posts
 
Hmmmm.....so now I'm torn between the KT88 Gold Lions or, for similar money, the Tung-sol KT120. Hifigeek1, if you were going this route, which would you likely go with? Thanks!
hifigeek1
770 posts
 
Well I'm not a fan of KT-88's in any ARC amp. I would make sure the output tube sockets were nice and tight and go with the KT-120's. Just so you know you can't just put any 6922's in that amp. I get them from ARC and it requires a 1-2 hour set up procedure so that distortion is low and the DC balance is correct.
gmorris
351 posts
 
Spinaker01:
Go with the KT120s you wont regret it. They will make a substantial improvement in your VT100MKII.
There are no issues re loose sockets, etc, as Hifigeek suggested.

I may not be a service rep, but I am very cautious and made sure that I investigated negative possibilities before making the change to the KT120s.
spinaker01 OP
491 posts
 
Thanks to all for your assistance on this. I plan on keeping the EH 6922 signal tubes, I just got through re-biasing them at about their midlife (using the A. Collins method). And my current output tubes seem to fit very snug, so I think a couple of quads of KT120's are on now on the menu. Will let everyone know how it goes. Cheers!
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