6550 vs. KT-120

[Bavarian05]

I would love to hear opinions on the difference between the two output tubes when used in a Ref 110.
Mine was delivered with the KT-120, though all of the glowing reviews out there are of the unit when running the 6550 output tubes.
Any feedback would be appreciated on the sonic differences when specifically used in a Ref 110.

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[karsajid]

I changed 6550 to KT120 in REF 110.

The KT120 has a more refined top end, warmer mids and better bass. Gives the feeling that the amp has better control on the signal.

[TMcD]

Originally Posted by karsajid

I changed 6550 to KT120 in REF 110.

The KT120 has a more refined top end, warmer mids and better bass. Gives the feeling that the amp has better control on the signal.

I would agree the K120 tubes sounded much nicer in my Ref110.

[jpgr4blu]

I agree that I could not find a single aspect in which the 6550s bettered the Kt 120s in the Ref 110. That being said, none of the differences were dramatic. I would put the improvement at 10%-12% across the board.

[Bobvin]

A little off topic, but can anyone recommend a good quality bias setting tool? The little plastic tool ARC provides is too skinny to provide controlled torque on the trim pot to adjust the bias. And for some reason (probably I have the wrong vocabularly) this doesn't seem to be an easy tool to obtain online. I bought one, with a ceramic tip, but it is too short and once the KT120s go in there will be less room. I hate the smell of my own skin burning upon touching a hot tube!