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
Vienna sausage=boudin blanc=linguica.  Well, it seems to be the case, at least to the dog the family had who would eat everything with the same gusto.
Look all I am saying is the Dybaco ST70.EL34 , Allen Organ Monos /KT120s, sounded darn close to the Defy KT88. Thats all I am saying,
Nothing to get all uptight about.
Its just a opinion.
Look, tell you what, When the high sens speaker arrives and i set up some sort of cabinet, I;ll get the other 2 amps back and we;’ll do some shootout., figure out if my above opinion , ain;’t worth even 2 cents.
Fair shake?

((off to the side whisper,,,I am really convinced the sonic will be mininsule contrast = power tube = power tube)


Apologies  to anyone whose apple cart I may have  bumped over,,,,...We really should not hold stiff doctrines in this hobby. 

Doctrines keep one from learning, , blocks new truths/experiences. it really does, The Dogmas.
I want to hear...errr...read the results of your shootout. When the EL34s in my PrimaLuna lost their mojo, the guy at Upscale quizzed me as to what my system was and what I wanted for it to satisfy me more. He suggested I try 6550's.  And yes, I'm a very happy guy.
OK mozartfan 12 foot pole.

Still on that "one driver fits all" kick I see.

I can't think of two valves that a more different.. 

KT88 sounds close to an EL34?

Man alive get your hearing checked.. and buy a speaker that REVEALS the difference in valves..

How about a GOOD small planar based system for starters..

Round speakers SUCK.. period.. Mid bass down, there is no other place for them in my home stereo..

Slow, sloppy, round speakers.. Pretty Simple really..
@mozartfan Look all I am saying is the Dybaco ST70.EL34 , Allen Organ Monos KT120s, sounded darn close to the Defy KT88. Thats all I am saying,

This could very well be the case with your source, your cables, your speakers, in your listening space.

Try each of those power tubes in the SAME amp(s) designed to accept all of them, paired with revealing speakers, and you may have a better chance of hearing the difference.
@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.
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".
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. 
FWIW, I currently use an upgraded (volume pot, Mundorf caps, Takman resistors, custom chassis etc...)  Elekit TU 8340VK PP amp (with a semi auto bias feature, easy and accurate) . My recent experience is that in the past year, I have used New EH EL 34, New Gold Lion KT 77 and New KT 88 matched tube sets. Each pairing has a separate and distinct sound... all were good, but different. The choice is yours but there was a choice to be made. I stayed with the KT 77.

BTW, I agree with the potential of the Wide Band concept, it is difficult to execute properly though. I currently use an auto-former modified electrostatic system but have started a Wide Band project, that will incorporate Cube Audio WB drivers and transmission line cabinets. 

The Truth is Out There....
ticat23 posts07-07-2021 3:46pmFWIW, I currently use an upgraded (volume pot, Mundorf caps, Takman resistors, custom chassis etc...)  Elekit TU 8340VK PP amp (with a semi auto bias feature, easy and accurate) . My recent experience is that in the past year, I have used New EH EL 34, New Gold Lion KT 77 and New KT 88 matched tube sets. Each pairing has a separate and distinct sound... all were good, but different. The choice is yours but there was a choice to be made. I stayed with the KT 77.

BTW, I agree with the potential of the Wide Band concept, it is difficult to execute properly though. I currently use an auto-former modified electrostatic system but have started a Wide Band project, that will incorporate Cube Audio WB drivers and transmission line cabinets.

The Truth is Out There....

~~~~~~~~~~~~~


OK 
we ;ve got another 
Mundorf + Takman  fan here. 

I love both labs components. . 
I  wnted to installa  Acoustic Dimensions 47 step vol pot on the Jadis DPL, but tech geek says, no go, won;'t fit,,,
Big loss there.

I tried the GL KT88's. sounded a  bit  muddy to me, 
Another guy on Audiokharma  says he also did not care for the GL, Alot of  folks love them. I am a  EHKT88 guy I am running Svetlana 6550s (same exact tube as a  KT88) So next set will be EH KT88's.

I wish i could go KT77 (=EL34?) but Defy is not flexible. 

I may end up buying my tech geek's modded Dynaco ST70/EL34. 



I had a modified Dynaco ST70 running EL 34's for many years (in a tri-amp arrangement driving Quad 57's along with T27's and Hegeman subs). Very nice, until I re-married and the "what are those..room heaters?" had to go.
I still regret selling the 57's AND the ST 70. Buy it to try it...

Onward and Upward...
El34 = KT88 = KT120

I hope you are kidding … if not, go see a specialist. 
Tube comparisons are only valid when the same amp is used with all the tubes in succession.


Boy, as the resident “expert” you sure make a lot of non-expert comments.

EL34s, KT88s and KT120 have different plate and grid voltages, they have different cathode current ratings. Ergo, they CANNOT be compared on the same amp. An amp will be optimized for one and not the others.



@pauly
Really?
Quicksilver’s Mid Mono amplifier is completely hand-wired and can use many different output tubes; the Mid Mono has a low loss output transformer, adjustable bias, and five-way gold-plated binding posts. Setting the bias is very simple: two screwdriver controls and pin jacks for any multimeter that reads millivolts. Power is 40 watts at 50% triode operation with the standard EL34s or KT88s, 45 watts with KT120s and 50 watts with KT150s.
Another!

The V4 recreates a musical event on a scale and with a solidity, roundness, and three-dimensionality matched by few and surpassed by no other amplifiers, with sensational dynamic-range to boot.” Paul Seydor – The Absolute Sound, October 2002.

“Connecting the Quicksilver Audio V4s quickly revealed that these were very good sounding amps indeed. Space, delicacy, transparency, and overall musical believably were of high order.” Bascom King – Audio, February 1998.

Powerful, musical, and effortless–this is the sound of the V4. As with all Quicksilver’s amplifiers, the V4s are all tube and hand wired point-to-point. A bias meter is mounted in the chassis and individual controls allow each output tube to be biased separately. The amplifiers come with KT150s, but EL34s, 6550s, or KT88s can also be used.


@yogiboy

Look at the specifications for the tubes.https://frank.pocnet.net/sheets/129/e/EL34.pdf
https://frank.pocnet.net/sheets/086/k/KT88.pdf

Plate voltage for EL34 used in push pull operation is 450v, it’s 560v for KT88s in push pull operation. Sure it will work with the KT88s, but not optimally.

Same deal for switching between triode and ultra linear / pentode. You want a higher plate voltage for triode mode. Ultra linear / pentode operation will also need more nfb than when operating in triode mode. If it’s optimized for one, it’s definitely not optimized for the other.

Doesn’t mean it sounds bad, but it’s not optimized as well as it could be. 

Besides, what are you doing with push pull amps? Get a SET amp and join us on the dark side. 😂🤣











@pauly
Here ya go!

PrimaLuna’s Adaptive AutoBias is a true, smart technology employing an array of sensors to monitor tubes and make adjustments seamlessly in real time. More important, it is the ONLY circuit of its kind that is truly "adaptive" by addressing "tube pinch off" at higher volumes, therefore reducing distortion by over 50% and greatly extending tube life. Adaptive AutoBias is completely passive and NOT in the signal path. The result is low to no maintenance, long tube life, and the lowest possible distortion for amazing sound. Adaptive AutoBias also provides unparalleled flexibility by allowing use of almost any tube on the market today. It even has a fine-tuning switch for EL-34 and KT88/KT120/KT150 tube types.
@donvito

Quite an impressive marketing spiel you got there Don ...

If you understand circuit design and you know what biasing does, you’ll recognize it as marketing hype. The circuit is (most likely) optimized for the smallest common denominator, in this case an EL34 operating in pentode / ultra-linear. The auto biasing will not bump up the plate voltage - and we know for a fact it doesn’t as the output is the same for EL34 and KT88 on the PL. An optimized KT88 has a much higher output that an EL34.

(Tip, look at the tube specifications)

Since they don’t even mention NFB, they probably don’t reduce that for triode operation either.

Not optimized by any measure.

If you understand circuit design, you’d know this. If you don’t, then we are wasting each other’s time.


" Adaptive AutoBias is completely passive and NOT in the signal path"

Telling me a PL is "special" as the auto biasing is not in the signal path is like saying a Toyota is special for having a steering wheel. I don't even know if you can get an amp with a biasing circuit in the signal path.

And hyping auto biasing as being "passive"? If auto biasing wasn’t passive, it wouldn’t be "auto" biasing now would it?

Folks in marketing tend to exaggerate ... a lot.  


El34 = KT88 = KT120

I hope you are kidding … if not, go see a specialist.


~~~~~~~~~~~~~~
Miniscle nuances, 
= same 
Miniscle nuances,= same

To you, I guess so ... I have no reason to believe you are anything but  truthful and I am not suggesting you are not. 

Where you go off track is assuming the rest of us have the same inability to hear the differences when the differences are quite blatant to myself and a few others on this forum.  

Honestly, I thought you were joking when I first saw your comments. 

My amp allows for all three and here is my take.

EL-34 > KT-88 > KT-120

At least that's the way these old ears hear it in my system with my amp.

Oz