Thank you Chrssain! Your post prompted me to swap out my KT-120s for the KT-77s they replaced several months ago. This was the first time I'd swapped the outputs since installing the KT-120s, and the comparison clarified my thoughts on the KT-120s and made me more aware of some positive qualities of the KT-77s. My tubes were used in Emotive Audio Vita mono amps which can use a variety of outputs ranging from the 6L6 family to the KT-120s. I ran the KT-120s at 65ma and the KT-77s at 50ma.
In my amps, here's how I would describe the tubes:
* The KT-77s have slightly more HF extension, a "sparkle" that is missing from the 120s.
* Bass with the 77s is slightly warmer and richer, also a bit looser.
* Leading edges of transients are slightly softer with the KT-77s.
* The midrange of the 77 is slightly recessed (or is the 120 slightly forward?).
* Micro-dynamics with the KT-77 are slightly better.
The above comments are what I would call objective. I am reasonably confident that someone listening in my room at the same time would agree with each of the above. On a more subjective scale, however, I would add that the KT-77s seem to be somewhat more free-flowing and less "mechanical" than the KT-120s. The KT-77s are perhaps more colored overall but are more fun to listen through.
All in all, both tubes sound great! I much prefer either of them to the GEC KT-88 for instance, and I am glad to have each of them as an option. However, I have to say that on balance I will probably go back to the KT-77 as my everyday tube.
I also have to add that my amps were not designed specifically for the KT-120. Most amps designed for the KT-120 use a higher B+ voltage that allows more power from the KT-120, but I have no idea how that would affect the sonics.
In my amps, here's how I would describe the tubes:
* The KT-77s have slightly more HF extension, a "sparkle" that is missing from the 120s.
* Bass with the 77s is slightly warmer and richer, also a bit looser.
* Leading edges of transients are slightly softer with the KT-77s.
* The midrange of the 77 is slightly recessed (or is the 120 slightly forward?).
* Micro-dynamics with the KT-77 are slightly better.
The above comments are what I would call objective. I am reasonably confident that someone listening in my room at the same time would agree with each of the above. On a more subjective scale, however, I would add that the KT-77s seem to be somewhat more free-flowing and less "mechanical" than the KT-120s. The KT-77s are perhaps more colored overall but are more fun to listen through.
All in all, both tubes sound great! I much prefer either of them to the GEC KT-88 for instance, and I am glad to have each of them as an option. However, I have to say that on balance I will probably go back to the KT-77 as my everyday tube.
I also have to add that my amps were not designed specifically for the KT-120. Most amps designed for the KT-120 use a higher B+ voltage that allows more power from the KT-120, but I have no idea how that would affect the sonics.