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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

Showing 5 responses by gmorris

gmorris
351 posts
 
FYI:
I spoke also to ARC. No problems were anticipated. The new bulletin about compatibility from ARC was issued in the Feb/March 2012 period.
gmorris
351 posts
 
Hifigeek1
My dealer Lyric told me the opposite. The VT100 MKII was on the list of approved amps for the KT120 upgrade. I was called specifically by the rep and given this info because I had enquired previously about using the KT120s.

Did you get the list from ARC or is your comment based on second hand info?
gmorris
351 posts
 
I retubed my VT100 MKII with the KT120s without any issues. The improvement in sound and perfromance was across the board in all sonic categories. In fact the amp seems to run cooler with these tubes.
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.
gmorris
351 posts
 
Oregonpapa:
The REF3 and PH8 both use a 6550C for power supply regulation.

Are you suggesting that based on these data points, Sinaker01 should use the 6550C instead of the KT120 as power tubes? Perhaps you haven’t noticed, but ARC has replaced the 6550C power tubes with KT120s in all of its current amplifiers.
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