Sonic Comparison between New Tung Sol 6550 vs KT120 vs KT150

[tubelectron]

I think the TS KT120 is an overall better sounding tube. The KT120 has just an overall well put together even-keeled sound. It’s been too long for me to characterize detailed differences between it and the new production 6550, but for my tastes, the KT120 hits the sweet spot.

No experience with the KT150.

Yes. I would say thatThe KT120 is simply an over-dimensioned KT88 or 6550, with the same (or nearly identical) curves. It can directly replace the KT88 or 6550.

^^ good points. This is all subjective. My experimentation was done in a push pull amp with a moderate 12 dB feedback. Your mileage may vary as they say. For example how they differ in a SE amp may be totally different.

My experimentations between a 6550, KT88 and KT120 were on my 12WRMS Ultimate KT120, a single-ended, cathode bias operation monoblocks amp, with a NFB of 6dB, that I designed to use the three models of tubes (max. plate dissipation 38W) :

I'll be honest : I did not found significant sonic differences between the three tube models...

T

 

[automojo]

IMHO you go with what the amp was designed for as far as power tube. The roll small signals. Some KT88's-like the JJ are more dynamic Sino KT88's, or Gold Lions.
On my Dark-swapping out the OPsvane KT88, for the 120's was a huge difference in bass drive. As well as a better midrange then any KT88 I have heard. Again_I use the small signals to fine tune.

 

[fxer1982]

I do not own any 6550s, but do own a bunch of KT88s. Do KT88s sound different than 6550s to you? I ask because Google says KT88s are Europe's answer to the American 6550. Of course Tung-Sol current production are made in Russia, so have no idea if they sound like American made 6550s.

Well I cant say for new 6550 tung-sol, yet NEW EH KT-88 compared to old tung-sol 6550 it sounded so dead with KT-88 then I broke my rule and put in the old 6550 WA-LA so much airy beautiful music difference of nite to day..I have not put in the KT-88 sence 16 months ago.. KT-88 still have only 1hr on them...quad of match KT-88

 

[automojo]

And IMHO-at least on the Rogue Atlas Dark-the mids of the KT120 are far superior to the NP GL KT-88, SIno,NP Mullard, JJ KT-88's.
Wids are sweet and detailed-very much like a El34-sans lean or plump bass. Full, deep and tight. The highs are plenty detailed with out the grain, or brightness or tipped up like 6550's can be.
With the Atlas Dark-IMHO the KT120's are the way to go. And fine tune with 12AX7's and perhaps 12AU7's as well.
I never liked the KT120 in any of my PL amps. The GLKT66 seemed to be the best tube on my setups.
They are still, even the EVO 400-a EL34 amp at their best from what I leaned with a Prologue 4, 5, Evo 300, and Prologue Premium.

 

[oldflame]

After having (mostly) only 6550's & KT-88's commonly available for "high power" audio, since the mid-1950's, in a relatively short time the KT-90, 100, 120, 150 & 170 appeared. I'm surprised it's profitable to make that many types, especially because there's not much difference between some.