Advice on KT-120 tubes

[Matsaly]

Greetings,

My LP70S amp has about 2,000 hours on the stock 6550 tubes. I am getting ready to tube roll and try KT-120's.
Previously I thought the sole option for this tube were the Tung-Sol KT-120's. I saw a review in Stereo Times of
the Shuguang Treasure KT-120 and would like to ask if anyone has listened to these? Any comments or suggestions are welcomed.

Cheers..

[Big Dog RJ]

Hey mate, nice amp the LP70S.
I actually liked the lp70s with the 6550's. we (dealer & co) tried different tubes on the amp and found if at all hardly a difference. maybe subtle changes in certain frequency areas but not a dramatic improvement compared to kt120's on a mv60se for example.

My overall experience with the kt120 regardless from Tungsol or another brand was fairly similar. compared to different brands of 6550's, there is a significant variance.

To justify to you that the S- treasure 120's are better than the Tungsol would be unfair and a bit mis-leading. I would suggest to audition for yourself to determine which tube your ears prefer. Afterall this is a very personal attribute and to me I preferred the Tungsol overall but at the end of our try out, we just preferred the lp70s with the 6550's!

The Kt120 is quite a funny tube, similar to the KT90 (which I didn't fancy much) may sound great on certain amps and not so "involving" on other amps. again it's a matter of preference. For example, the kt90's were superb on bass but lacked the lush midrange of the 6550c. The kt120 does both ends of the spectrum very well but may not improve an existing design that was not designed around the kt120 circuit, as is the case of the lp70s.
These were our findings however I am sure you may feel different onced you've experienced these tubes.
hope that helps! Cheers,RJ

[Matsaly]

Thanks for your input Big Dog RJ. I followed your advice to try them and see if they were to my "taste". I bought a set of Cryo'ed Tung-Sol KT-120's from Upscale Audio and have about 80+ hours burn-in time on the tubes. My preliminary observations are that they are more dynamic than the stock 6550's. They have considerably greater authority in the bass and seem more open and extended in the treble. However they do seem a bit "cooler" in the midrange. I need to listen to them more extensively to see if the "cooler" midrange is to my taste.

[Big Dog RJ]

Hey mate,
Trust all is well so far with your LP70S; just checking how those KT120's are faring?

Has the midrange improved or is it still a bit laid back?

Overall, the KT120 is a far better tube but that again is certainly a significant improvement if the amplifier was initially designed for KT120's. As I said before, on the MV60SE this was quite significant but then when I had the Classic60SE, the KT120's were far superior on this amp compared to any cj amp I previously owned having 6550's. I really couldn't tell if the LP70S would be a good improvement with the KT120's or not, as was the case with our experience on the cj dealer's setup. All I could confirm is that the LP70S was one very "musical" sounding amp with the standard 6550C's.

Obviously you may have a different view/experience. With the midrange, I would closely look into piano, strings and voice improvements in depth and timbre, bass and highs should definitely be in better control and sound "fuller" but it should not "choke or muffle" the midrange. That overall "well-balance" in sound is what the KT120 should be able to deliver, along with some superb control and smoothness. Should have an effortless presence to the soundstage without any strain or harshness whatsoever...
Hope this makes sense, let us know how it's taking shape.
Cheers and enjoy, RJ