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KT66s in place of KT88 tubes

I expect there will be a change in bias, and a reduction in power. But on the basis that lower power tubes generally produce more faithful sound, can one put KT66 tubes in an amp usually requiring two KT88s per channel? I'm thinking about a pair of Quad II/forty push-pull monoblocks.

dogberry
jond's avatar
jond
5,905 posts
 

Yes the KT66, and KT77, are better sounding tubes than the KT88 but definitely check with the manufacturer before you fry your amp!

hilde45's avatar
hilde45
5,050 posts
 

My amp permits KT66, 77, 88, 150. It seems amp-dependent.

jjss49's avatar
Ag insider logo xs@2x
jjss49
6,612 posts
 

specifics always rule the day 

generalities only lead one astray...  

poetry to live by 🤣😂

dogberry OP
702 posts
 

Thanks, all. Time for me to talk to my tube guru.

C.

weebeesdad's avatar
weebeesdad
140 posts
 

@jond (and any others in the know) - What sonic improvements do you think I would realize replacing KT-88s with KT-66s? I understand that this will be amp specific but even a generalization would be helpful. I am currently using KT-88s (two per channel) in a pair of DeHavilland 50A mono blocks which will accept KT-88, 6550, 6L6GC, KT-66, and KT-90 output tubes. 

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