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El34 = KT88 = KT120

Sure the KT120 is 2x;'s the size of a EL34.
But in my limited expereince ((thus far,,have 1 more experiement just ahead when my new speakers arrive and I build the cabinet, then further testing of the 3 types can begin) 
You get something nice of one tube vs the other 2, and another of he 3 shines better here, the last is slightly superior in this/that aspect.
6 of 1 /half dozen of the other.
I mean it all boils down  gain here, and give up something there.

Power  tube = power tube. 
I would not make such a  big deal over the comparisons. 
Thats said.
I think for me , i prefer the EL34 of all power tubes (as I've been told its the best of the 3) , Why?
Because its the ideal tube in a  PP amp for a  single wide band speaker. 
But i could be wrong, 
Will test out the 3 tubes in a few weeks. 
I actually could not hear much differences on the Seas speakers. All 3 sounded so very close. 
You might say the Kt120's out shoot the tiny EL34 in the  low bass fq's. 
I have Mundorf caps in the amp, these high end caps  adds a  nice punchy bass to any tube in the socket. 
The EL34 has just about same bass as the huge KT120's. 
I just don't see much difference  to debate the issue. 
mozartfan
rushfan71
295 posts
 
@edcyn I wouldn't be surprised if you were just hearing a difference from those inferior PL El34's.

I replaced mine with a matched Octet of 1960's Mullard El34 xf2's.
More refined less glassy sound.

And of course you should know that the (2 ) 12AU7's in the center front position in your Amp would be the first tubes to roll for the most immediately noticeable s
SQ change.
rajugsw
219 posts
 
My Jolida 3502p runs KT150's. The original KT88's were never used and I sold them to a happy Customer. Love the sound they make in conjuction with my BAT VK50-SE with it's eight 6H30 Russian "Super Tubes".
boomerbillone
357 posts
 
Hello mozartfan.  Be sure that the tubes are biased properly. The proper bias may differ for the different tubes. In general, the tube working the least hard will last longer. So the KT120s should outlast the others. If the price of the tubes is not a factor, go with the KT120s if the sound is good. Bob Carver is using KT120 in his amps and he runs them so cool you can put your hand on them. A remarkable tube! Enjoy the music!
jasonbourne52's avatar
jasonbourne52
2,863 posts
 
Tube comparisons are only valid when the same amp is used with all the tubes in succession.
yogiboy's avatar
yogiboy
5,725 posts
 

+1jasonbourne52 " Tube comparisons are only valid when the same amp is used with all the tubes in succession."

My amps allow changing tube types. I prefer the bigger brighter sound of a KT88 compared to the laid back sound of a EL34. It also depends on the speaker that you are using.
I have never tried a KT120 or a KT150 so I can’t comment on those types!
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