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
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!
Tube comparisons are only valid when the same amp is used with all the tubes in succession.

+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!
LOL. I like 6550s over all the KTs. The EL34 is a sweet tube for certain kinds of music, but not for what I play.

boomerbillone
113 posts
07-07-2021 2:39am
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!

~~~~~~~~~~~~~~~~~
Yes My tech geek perfers the KT120;s IF the amp can't handle the tube. 
Pity most amps are designed around 1 particular tube. 
Yes I plan to bias a  new set of KT88's even lower than now, My tech geek refuses, but its my amp, . 
I want to get more life out the tubes , X12 tubes, After the Thor upgarde disaster I'm really cheap now. Penny pinching + after all the chinese wide bands I've been testing out, Worth the experiement./ 

You know folks can try to explain how a  wide band works, sounds, but until  you acutally get one working in your sysytem, one is completely in the dark. 
~~~All audiophiles MUST have at least 1 pair of wide bands in the system , ~~~~~~~~~~~~~~~~
The sooner the better. 
$200-$400 bucks, thats all to start the testing. 
Then  dump them at 1/2 paid on ebay. 
This is the ONLY way you know how your xover speaker REALLY sounds. 
Otherwise you are in the fog.