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New tubes...far more power??

I replaced my quad set of KT150's in my tube mono blocks a few days ago...replaced with a new set of KT150's that were quad balanced and now for some reason the power output is considerably more. So much so that i need to drop the volume control on my preamp by three notches! Plus, the sound quality is actually no better than before...and maybe even a little strident! Anyone have any idea as to why this would be? 
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roberjerman
4,319 posts
 
All tubes, both large and small, produce varying amounts of harmonic distortion: 2nd, 3rd, 4th, 5th ... And this is measurable. Your new set probably has a different harmonic distortion signature. Which you noticed and did not like! There is no "cure" for this! Just accept it - or buy a set from a different manufacturer. And hope that they will have more pleasing sound! 
roberjerman
4,319 posts
 
And if you think that your power tubes will sound better with use - forget it! Tubes, unlike say, wine and whiskey, do not improve with age!
grey9hound
1,112 posts
 
They do have a require a little break in time , just like anything else does.
Probably 50-100 hours
tooblue
1,945 posts
 
I am not aware of anyone manufacturing KT150 tubes other than Tung Sol. As far as tubes not inproving/settling in with some burn in, is not what my ears tell me. Just sayin.
dweller's avatar
dweller
3,795 posts
 
Have you unplugged the amp since removing the old tubes? Your auto-bias circuit may be retaining the settings it used with your old tubes. Sometimes unplugging the amp resets to "factory settings". Leave it unplugged for an hour or so. I'd even remove the new tubes after unplugging ( plug them back in before restart). 
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