I am becoming an ever increasing fan of both the KT-120 and KT-150 output tubes. My first experience listening to the KT-120 tube was with the ARC VS115 I bought that ended up claiming my right bicep tendon. I wrote about the VS115 and the sound of the KT-120 tube on this forum several years ago. I bought the VS115 to tide me over while my KSA-250 was making another round trip to the Krell factory. I remember thinking that I was going to be in for a let down in the bass department when I switched over to listening to the VS115. Historically, some of us know that bass from tube amps is found lacking in extension and tightness in comparison to SS amps with big power supplies and high dampening factors. I think all of that is changing now and I think it has been changing for awhile. I remember remarking about the VS115 that not only was I not let down by the quality and extension of the bass in comparison to the KSA-250, I actually had to turn down the bass levels on my speakers I had at the time.
My first exposure to the KT-150 tube came when I reviewed the Raven Silhouette Reference monoblock amps a couple of months ago. Once again I was impressed with the quality of the bass and the extension of the bass. But more importantly, I'm impressed with how the KT-120 and KT-150 tubes sound from top to bottom. I have never been a big fan of any of the 6550/KT-88 tubes before with the exception of the real-deal NOS Genelex family of KT-88 tubes. Those are really very special tubes that have it all from top to bottom. Any other tubes I have heard in that family of 6550/KT-88s has paled in comparison. And I make no claim that I have heard all of the contenders, but I have heard some of them. GE 6550s have nice bass punch and leave me cold in the rest of the frequency spectrum. I never liked the SED KT-88 tubes nor was overly thrilled with the Gold Lion KT-88 reissues. Raven Audio sent me two quads of NOS Tung-Sol 6550s to listen to in addition to the KT-150 tubes. While I could admire the creamy midrange of the Tung-Sols, they just aren't capable of making equal power across the audio band like the KT-120 and KT-150 tubes.
So now I have an ARC REF 75 that comes with the KT-120 tubes and the amp has a long way to go in order to break-in. However, stone cold out of the box, I'm still a happy camper and once again I'm taken aback with the bottom end of this amplifier and the KT-120 tube. With regards to output tubes, we may well be in the golden age of tubes. My opinion may change later, but for the here and now I think both the KT-120 and KT-150 tubes are solid home runs. They are cut from the same sonic cloth from top to bottom instead of being a Frankenstein tube with one kind of bass, another type of midrange, and yet another type of highs. If you have a tube amp and you can use either the KT-120 or the KT-150, I highly recommend that you give them a try.
My first exposure to the KT-150 tube came when I reviewed the Raven Silhouette Reference monoblock amps a couple of months ago. Once again I was impressed with the quality of the bass and the extension of the bass. But more importantly, I'm impressed with how the KT-120 and KT-150 tubes sound from top to bottom. I have never been a big fan of any of the 6550/KT-88 tubes before with the exception of the real-deal NOS Genelex family of KT-88 tubes. Those are really very special tubes that have it all from top to bottom. Any other tubes I have heard in that family of 6550/KT-88s has paled in comparison. And I make no claim that I have heard all of the contenders, but I have heard some of them. GE 6550s have nice bass punch and leave me cold in the rest of the frequency spectrum. I never liked the SED KT-88 tubes nor was overly thrilled with the Gold Lion KT-88 reissues. Raven Audio sent me two quads of NOS Tung-Sol 6550s to listen to in addition to the KT-150 tubes. While I could admire the creamy midrange of the Tung-Sols, they just aren't capable of making equal power across the audio band like the KT-120 and KT-150 tubes.
So now I have an ARC REF 75 that comes with the KT-120 tubes and the amp has a long way to go in order to break-in. However, stone cold out of the box, I'm still a happy camper and once again I'm taken aback with the bottom end of this amplifier and the KT-120 tube. With regards to output tubes, we may well be in the golden age of tubes. My opinion may change later, but for the here and now I think both the KT-120 and KT-150 tubes are solid home runs. They are cut from the same sonic cloth from top to bottom instead of being a Frankenstein tube with one kind of bass, another type of midrange, and yet another type of highs. If you have a tube amp and you can use either the KT-120 or the KT-150, I highly recommend that you give them a try.
department. I think I will pass on the NOS 6550 tubes.
