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KT-77 vs. KT-66

As I've had my QS Mono 60s, I've tried a variety of tubes. I have sold off my KT 150s, and use KT-88s from time to time, but what I really love are KT77's.

I'm thinking of getting some KT66s, thinking that lower powered tubes are better (to my ears) matches for my system. I just don't know what the KT-66's sound like. 

Question: If you have compared KT77 and KT66 tubes, what would you say the sonic, audible characters of each are? Is there a difference you can hear? What does the KT66 sound like -- to you?

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Showing 1 response by xenolith

xenolith's avatar
xenolith
120 posts
 

@jjss49: excellent point. The designer/builder of our 75 lb. 100w monoblocks which run 2 x 6BL7 + 4 x KT77 told me (paraphasing) ’everything is designed around optimizing sound from KT77s. The only other output tube that can be correctly biased (they use an individual tube fixed bias system, ie. trim pots on each output tube) is EL34, but it won’t sound as good as with KT77s. No other output tube can be correctly biased.’

Note that the output transformers are rated to 200 watts, so thought I’d try some higher wattage output tubes, but he was right; couldn’t get correct bias with KT88s...also tried EL34s and he was right again; while the tubes biased up just fine, the amps didn’t sound as good. Funny, I would call what was lost "focus".

Super focus with KT77s though!

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