2. tech-talk
  3. 167830-136265

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
yogiboy's avatar
yogiboy
5,451 posts
 
@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.


pauly
1,012 posts
 
@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. 😂🤣











donvito
393 posts
 
@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.
pauly
1,012 posts
 
@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.  


mozartfan OP
2,143 posts
 
El34 = KT88 = KT120

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


~~~~~~~~~~~~~~
Miniscle nuances, 
= same 
More to discover