Power Tube shootout 34,6550,88,120,150

just for all practical purposes, l lets leave out the 66,77.
OK, so now, lets imagine we are testing the 5 power tubes listed about witha  pure neutral colorless amp (just for all things being equal, pre tubes all equal, pure colorless) We are comparing these tubes based on each tubes ~~Unique ~~Individual~~ Charatcer , regardless of lab make. New production only, as NOS are not found in any quantities , nor  at reasonable price points. 
I would say the most important  quality to be discussed is midrange. 
For bass, its quite simple to add a  sub amp/woofer,,and highs,,well maybe a  new high tech Neo Beryllium  woill solve that issue.
Although it is true we need to add footnotes on bass/high fq response.
Most importnatly, is how does each tube  resolve 
1) Voice
2) separation of instruments
3) purity of midrange fq resolution
4) low mids/upper mids response
5) openess/sound stage, = low  distortion at higher levels of complex music, say a  full orchestra.
Please add  other characteristics which should be brought into the comparison.
Many of you have years , decades of experience with each power tube in many dif famous power amps, , your imput will be greatly appreciated by all of us newbies  in this grey area of which  power tube suits our needs best  concerning the music we listen to.
Based on my very limited experience with power tubes, so far I have found the 88 to be my ideal tube,,however,,,seems i may have overlooked the ~~6550~~, based ona  short YT vid, of some chinese lute/female voice,,shootout 88 VS 6550,,2 minute vid,,I may have to change my opinion of recent posting ** The KT88 is the best and finest power tube ever made**,,That opinion , may have to be adjusted, to say *2d best*, as i await a  purchase and testing of the 6550, in 2 weeks time. 
My hunch based ona  2 minute compressed  YT upload then further compressed to my comp and $10 comp speakers,, i surmise it is the 6550 which is my ideal power tube. 
Which would make the 6550, IMHO the finest power tube ever designed.
I am hearing things i heard on my JOR with  the famous EI KT90's. = life like vocals, ,,but with the added bonus of tingling, sparkly highs. 
As I say I could be wrong,,but my hunch and intution says i am spot on.
here is the 2 minute clip  on which i base my daring  ~hunch~~.
The 6550 and 88 look very close in construction,,but that might be where it ends,,looks is one thing, performance can be quite another.
Take the 12AX7,, Not any 2 sound  alike,, all have shades of dif voicing.
(I'm a solid fan of Tele, and no others)
I had assumed a  power tube is a  ,,,power tube,,= we are talking power , less about nuances. 
Could not be more wrong.
Although I hear the  tele AX as set apart from all other AX's...in power tubes,,the voicing is perhaps even greater than in pre tubes..where as pre tubes adds a  nuance here, alittle there,,, power tubes vary significantly from each others voicing,,but wait,,that could be wrong,,as i recall, the 90, was very close in voicing as the 88, the 88 offered more openess. 
I sold off my 9-0's, so can not follow up on that shootout.
in fact to be fair to the 150,,i heard this magnificent  constructed tube, with the old Jadis caps, and the 88's with the new M caps... so all things were not equal.. However,,I have the hunch,,the 150's would still retain that ~~blob like, mushed meal mids/rolled off high mids~~ with the new M caps. This is what i am getting at.
We need to bring up our experiences of the fundamental character of the power tube, regardless of quality caps,  quality of amp.
Almsot like trying to hear the power tube itself apart from the components involved. 
The EL34 I hear as a  bit weak, limp vs the 88. So I give more pointsb to the 88. 
The 90, as i say,,was very nice,,but not as full, rich, open as the 88.
again 88 remains as champ,,I have not herad the 120,,but based on my experience, rather limited of the 150,,I'd guessing the 2 are cousins, and thus , lacks the mid clarity i am looking for. The 150 packs low bass,, makes a  great tube fora  bass guirat amp,,not for rich mid range which is required for   clasical,  human voice, jazz.
Bigger is not alays better, and in this case very ture.
Once the 6550's arrive, i will quickly upload a  YT vid,, which will give me further substance , evidence to my hunches. 
Here is the shottout twix the very popular 88 and the rather not mentioned as often the 6550
**all power tubes have their respectful qualities~~ I ain't buying, 
WE are searching for ~~The best of the best~~ in power tubes,, Only 1 tube can be left standing at this shootout, No survivors. Only 1 tube has the fastest gun in this power tube shootout. 
There is no topic anywhere on the Inet where you can see a  fair , honest, and based on bonifide experience, ofa  shootout twix these long standing popular power tubes. 
I am looking for 1 gun standing alive in this wild west town. 
One power tube will be  given the  crown as ~~King of all Power Tubes~~
My biased vote is already in, all money riding on  The 6550.,,as best gun in the west. 


Its crazy,, i just googled 6550 vs kt88 and came up witha  2006 topic i initiated on audiogon,,with alot of inaccurate comments from my postings.
Others corrected some of my very faulty opinions.. so here i am , 14 yrs later,,right back at the 
kt88 vs 6550, yet once again,,just weeks away from the acutal shootout,,, not with the JOR as i had back in 2006, now with the Defy.
anyway,,here's the old post.
My guess is the 6550 will draw the gun cleanest, with sparkle and shimmerings in  upper mids/voice.
I am trying to capture what the JOR/EIKT90 offered,,a  live muisc show in your room, but w/o that screetchy high fq given off by the EI distortion.

also read Dentdog's comments  from July 2017
where he  backs up my  hunch the 6550 is the superior power tube
about 5 posts from top
Read sand and glass comment july 2017,,more than half way down
**If you want more of that tube sound,,,BEST TO AVOID the 120/150***< I can validate his comment based on my exp of the kt150.. ** Bigger is not always better** especially in tubes,, Sure the 150's are very impressive, STUNNING construction,,justa  gorgeous  even COOL looking tube,,, and thats why i went after them,,also i read a comment  from another audiophile forum **WOW the kt150's are in, awesome!! tube** so i fell for it. 
$800 experiement, floped, now on the auction bloack.
The 120's i;'ve not heard,,but doubt they will  offer what i personally am looking for in mid range FQ resilution.

sandand glass posting , more than half way down.
Read Bombzilla's post Nov 2016,, ,,where he says
&&and the major **advantage** of the kt  tube models  is increased power output~~that I don't need or use~~I've decided to stick with the original 6550 tubes**
man had I read this last year,,and followed his opinion,,,could have saved a  large fortune,...

I'm finding solid opinions, leading to the 6550 as the  best shooter in town. 
The shootout will be fair and unbiased,,, I am not going  to give points where un-earned. 
ears will be perked and mind  focused, clear. 
The Defy is a good amp to stage this shootout, as its neutral, no coloring. 
Member DAK808’s response in that DIY thread is notable. He correctly points out higher current/plate voltages and larger transformers typically required and used by amp designers to run larger KT150 tubes (properly).

Also, i.e, noting the newer "MKII" versions of the Jadis JA80 amp is optimized to run the larger KT150 tubes http://www.jadis-electronics.com/en/ja80-mkii-21.php

Quote (DAK808) @DIY:
"...a tube has certain minimum requirements to do its job which is to amplify the signal put on its grid. The voltage and current requirements for the tube is supplied by the power transformer. The larger tubes require more current and voltage than the lower output tubes"...
My tech guy down here Randy Cohen, mentioned the KT150's need to be perfectly matched, so he can raise the plate current so the tube can work as it was designed to perform,,at higher current,,but for some reason he had issues with jadis'  biasing screw,,1 for each row of 3 tubes,,,Mentioned the tubes are not  running at **optimal** conditions..was afraid to raise the current and damage trans.. Mine is Mark 2, early 2000 production,,I think.
anyway,, at the very least i can get some idea of the 150's voicing on mid range,,my critical area for CM..= not what i am looking for,,,
I am looking at several listinsg for 6550's on ebay,,,Honestly the construction looks identical to 88.
Seems as i  recall, the 6550 is a shorter tube vs the KT88, other than that, identiacl construction.