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. 

https://www.youtube.com/watch?v=oC1AVIsqoB8&t=3s




mozartfan

Showing 2 responses by decooney

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"...
The sound does change notably with +/- bias on my amps running KT150s.  I can swing 20ma either way. If I back it down, the tone changes to EL34 type sound and the soundstage recesses back. If I raise 15-20 ma, the midrange comes out and forward, and the sound stage comes forward too. 

My amps have notably larger transformers and close to 2x the plate voltage to it's smaller self that runs EL34s.  The downside is I cannot run smaller tubes in mine, it will burn them out prematurely, so KT120s or KT150s it is!  They don't sound right until they burn in 100+hrs.  I now truly enjoy the the KT150 output tube sound WHEN mated with proper triode small signal/ driver tubes and proper coupling caps in the amplifiers. Transforms into a very pleasant result. Powerful yet smooth and musical, and with moderate bias, tubes and transformers are mildly warm, not hot at all.