A quick sense of the kt120 tube

I recently had my Sonic Frontier Power 2 upgraded by Chris at Parts ConneXion and we decided on his advise to try the new kt120's. I like the 6550 but like more the sound of the kt88'. I am running Wilson WP7's and greatly prefer tubes over ML ss (23.5). I have been most satisfied with the 88's and the Wilson's.

The KT120 in my system has created a significant improvement with no obvious compromises. Chris said the kt120's would sound like really good kt88's and I agree. He also said that the kt120 is considerably more robust and is generally loafing when used as a replacement for the 6550/kt88. They should last considerably longer. Great.

The obvious difference? With these tubes, my system has a new and supremely enjoyable sense of the "power" of the music. Delicate sounds are still delicate but there is more body and presence, closer to the emotional content of live music. To be clear, I am not talking about being louder which often sounds like (and is) more power. The volumn is the same as is the scale but there is still more music, a phyisicality that I call "gravitas". I can listen into the music as deeply as ever and all the tube magic is still present. For me this new presentation is just fun and you don't need to be in audiophile mode to notice or enjoy.

I offer a single example. My wife and I were in D.C. at the National Cathedral and happened to catch evening Vespers
with the male choir and the BIG pipe organ. Let me again emphasise the BIG pipe organ. If you have never heard a truly great pipe organ in a hugh space, take your imagination as fare as it will go and you'll still be a little short. Again, it is not just loud but it is BIG and POWERFUL and seems to be able to shake solid stone. It can humble all other musical sound. The "organ" in my listening room is now "BIGGER and more POWERFUL", not quite like reality, but closer than before with either ss or tubes. The Wilson WP7's can sure do base.

Thank you Chris.

I am not a technical expert and you can do research on the 120's to answer those questions. I will be glad to try to answer any listening questions.
hi, how is clarity and low level detail ? I am interested in the kt120s, but I dont want a thicker, darker sounding tube, I am currently using gold lion kt88s in rogue audio m180s with revel speakers, thanks, Chris
Anyone else have any thoughts or opinions they'd like to share regarding the KT120 tubes in their amps/systems?

Just adding this list to help out anyone who may stumble upon this thread.

Credit for this goes to A'gon member Hifigeek1. He posted this on another thread.

04-19-12: Hifigeek1

The following is a list of ARC amps that are authorized to use the KT-120:

VS55, VSi55, VS60, VSi60, VS110, VS115, REF110, VM220. I hope people find this useful as there seems to be a lot of confusion about it.
In comparison with my favorite in this genre, the kt 120 is slightly warmer, fuller, relaxed, and give up a bit of top end detail to the winged C 6550. The kt 120 is a great tube, sonically and a great alternative to others. I find the 120 better than the Gold Lions. Try first....jallen
Hi Jallen

Thanks for sharing your thoughts about th KT-120s. Good to know about the slight loss of top-end detail. I like a bit of detail in my music but sometimes I've been hit with a bit of harshness fro the highs with some of my previous systems. Are your KT-120s matched from the factory or cryo treated? I'm just curious since I've found there to be about a $25 difference in pricing of quad sets of KT-120 tubes from various e-tailers. There's also a place that has a premium matching service for these tubes. A quad is about $200 as well.
They were matched non cryo tubes. Jallen

Thanks for these insights on the KT120 tubes. 

You mentioned at the start that Chris did some upgrades on your SFP2.

Just wondering: did the upgrade include just the new tubes?  Or were there some other component changes? Caps, Resistors, Wire?

I’m just thinking that perhaps the new tubes were not solely responsible for the sonic gains you realised?  Maybe it was the other upgrades?

What else was changed, before you received the retubed amp back?