Plans for ARC Ref 150 with KT-150s? (like is in the works for the ARC Ref 250)

[Bobvin]

Hi Max do you have REF750s? You are a most fortunate audiophile. You know of course that each chassis takes 16 tubes. I don't even know how one would say "a matched sixteenplet", times two of course for 32 KT150s. In this scenario having carefully matched tubes would, I imagine, be ultra critical for ultimate performance. Having a single tube drift out of compliance would impact the the entire channel, and matching 16 (32) would require sorting through a very large sample set. Much easier to match up a quad than a sixteenplet.

[MPS]

Originally Posted by Bobvin

Hi Max do you have REF750s? You are a most fortunate audiophile. You know of course that each chassis takes 16 tubes. I don't even know how one would say "a matched sixteenplet", times two of course for 32 KT150s. In this scenario having carefully matched tubes would, I imagine, be ultra critical for ultimate performance. Having a single tube drift out of compliance would impact the the entire channel, and matching 16 (32) would require sorting through a very large sample set. Much easier to match up a quad than a sixteenplet.

Not sure about REF750 but at least in VT200mkII matched quads are required. Tubes are being biased in groups of four, it's not necessary to match all 16.

[max17]

Actually I don't own REF750s (only the much more modest Ref150) however I only ask out of curiosity. When I purchased (8) KT150's for my amp I assumed they were basically matched as pairs. Each matched pair needs to have the ability to be biased within a certain range having only a single bias adjustment for the pair. I didn't think it mattered how closely each tube pair had to be matched in relation to another tube pair as long as each pair could ultimately be biased within the required range. I guess that is my question - Does each tube pair need to be closely matched to all other tube pairs in the amp?

[max17]

MPS - thanks for the info on the VT200mkII. So I would then assume that the REF750s tubes would need to be biased in groups larger than 4 (maybe 8 or 16) which would make tube matching understandably very difficult.

[max17]

Looking at specs for each model of REF amp I now understand. REF75 includes individual biasing for each tube, REF150 and 250 are biased by tube pair, and the 750 is biased by tube quad.

[Number95]

Originally Posted by Bobvin

Hi Max do you have REF750s? You are a most fortunate audiophile. You know of course that each chassis takes 16 tubes. I don't even know how one would say "a matched sixteenplet", times two of course for 32 KT150s. In this scenario having carefully matched tubes would, I imagine, be ultra critical for ultimate performance. Having a single tube drift out of compliance would impact the the entire channel, and matching 16 (32) would require sorting through a very large sample set. Much easier to match up a quad than a sixteenplet.

Matching is required for 4 sets of 8 tubes for Ref750. There are two sets of 8 tubes per channel which one tube in each set is user controlled to the recommended bias setting. Yes matching 8 vs 4 is still harder work but no need for 16.

[TONINO61]

[IMG][/IMG]

[Felice]

It's amazing how overwhelmed the the much to small power transformer even more power.
Such a small power transformer Europe is a no go!