[Puma Cat]

Originally Posted by Joe Appierto

Naturally, that’s going to some degree depend on the amplifier you’re using and the associated system. Your unmodified Premier 12s, I’m guessing, fall somewhere between bi-amped 11As and the Premier 140, maybe.

There are two main schools of thought here in this forum. And please guys, if I’m misstating anyone’s feelings, please jump in because I don’t want to put words in anyone’s mouth.

Okay, I will keep that in mind!

Originally Posted by Joe Appierto

The majority view is that the KT120s combine the best characteristics of the 6550 with the KT88. They may not be more powerful when used in a circuit not designed for them, but they seem to be a little more dynamic and have better headroom. They present a strong bass line without bloat and are articulate in that presentation. Mids and treble are smooth without being rich or warm.

I completely agree with this and would add that the presentation from top to bottom is superior, but I do think that KT120s are more musical (sweeter?) than you describe here; in essence, they combine the best characteristics of the 6550 and KT88.

Originally Posted by Joe Appierto

The minority view (caveat: I’m one of this group’s members) is that the KT120 is an excellent sounding output tube. However, when compared to a good 6550 (e.g., SED =C= 6550C or a Tung-Sol reissue 6550), the KT120s lack a little top-to-bottom coherence, may be a little bit on the rich side of neutral and don’t have the same degree of clarity in the upper midrange and lower treble.

For the most part, I disagree with some exceptions. In my experience the top to bottom coherence of the KT-120 is superior and there is no difference in upper midrange/lower treble clarity or air. The bass performance is markedly better. I do agree as mentioned above that the 120s are a more musical tube, which is fine with me because I found 6550s to be in general a bit too cool for my taste (this is based on Winged C 6550s, not Tung Sols, bear in mind). Overall, I find the KT-120 to be superior in pretty much all respects to 6550s and I ain't goin' back! So, I'm with Myles on this one....

Bear in mind that I firmly believe that a tube's performance is highly dependent on the circuit topology it is going into, and my views are based on KT-120s in an LP70S.