By Michael Miguest
There is a caveat to my subjective statement that my Ken Stevens' Convergent Audio Technology (CAT) SL1 Signature upgraded MKII to MKIII is a masterpiece. Subjectivism is based on or influenced by personal feelings, tastes, or opinions. With that in mind, the CAT MKIII after some tube rolling, allows me to achieve an incredible musical presentation at a price point that in my opinion, is sane. When it plays music, it sounds like music. It's transparent, textured, neutral, inexorably revealing, insightful and along with its pace, rhythm, attack and timing (PrAt), is more life-like than virtually any other preamp that I have experienced. I'm sure the build quality contributes to CAT's incredible performance. Both the main unit and power supply feel like solid masses. It is constructed like the proverbial Brick (expletive) House.This is due to their steel chassis and the liberal use of what Ken Stevens calls a "resistive damping compound" internally -- the blue stuff you'll see adhered to much of the main chassis's internal surface area. The steel and damping compound were chosen because they control resonance, something CAT takes to great lengths. Circuit boards are made of G200, a material that's 12 times more expensive than the substrate used for many of the circuit boards in other high-end products.
With regard to my system, my tube power amp is a VTL stereo 90 running 6550 Tung Sol power tubes with a pair of Valvo Blue Label pinched waist 12AT7 and a pair of Telefunken ECC801S signal tubes. The Cat SL1 Signature MKIII is a synergistic match created in Heaven. My Digital front-end consists of the Mark Levinson 390S which I use as a transport that feeds a Monarchy NM24 Dac that uses 6922 vacuum tubes and is powered by a Monarchy AC-Regenerator. The CAT SL1 Signature MKII used 12AU7 tubes in the V6 and V7 line stage positions which was changed to 6922 tubes in the MKIII. According to designer Ken Stevens, the 6922 is a better input tube than the 12AU7, and allows the SL-1's noise level to be reduced from -92dB to -112dB (unweighted). Apart from the noise figure, the electrical specifications stayed the same: gain is within ±0.1dB of the Mk.II; there is no change in rise time, bandwidth, or slew rate. Still, Stevens says the sonic improvement is such that he seriously considered renaming the preamp the SL-2. I ran across this information from a stereophile review:The 6922 has been part of the SL-1's tube complement, but not in the line-input stage. The SL-1's design calls for the tube in this spot to have a plate voltage of 175V, and published 6922 specifications state that the maximum allowable plate voltage is 130V. The tube that Stevens now uses as the line-input tube is made by Sovtek in Russia, and has the European designation of E88CC. Although labeled 6922, it has—as Stevens discovered when reading the instruction sheet packed with the tubes—a maximum plate-voltage spec of 220V, well within the SL-1's requirements. To accommodate the new tube, the gain was padded down. There are no other circuit changes. My Analog front-end consists of a Thorens td 126 MKIII with a Denon 103r cartridge that feeds my Allnic AUT 2000 step up transformer which feeds the CAT's phono inputs. Last, but not least, my system has a Revox a77 High Fidelity reel to reel tape player.
When it comes to tubes, my tastes prefer NOS vacuum tubes. Ken's SL1 Signature MKIII is supplied with (Sovtek) 6922 and (EI ) 12AX7 tubes. I subsequently rolled a pair of Telefunken E88CC in the V1 and V2 positions and a pair of Telefunken ECC83 smooth plates in the V3 and V4 positions of my Phono Stage. I left the Sovteks in V6 and V7 because of the plate voltage issue but rolled a pair of Mullard MC-1s in the V8 and V9 positions in the Line Stage. You would have to hear the musical presentation with this tube combination.
In conclusion, my personal feeling is a "Masterpiece" is the work of an artist who has been absorbed by the spirit of his/her times and can transform personal experience into a universal one. Masterpieces make us forget the artists, and instead direct our attention to the artist's works. We may wonder how a particular work was executed, but for the time being, we are transposed, so deeply brought into this creation that our consciousness is expanded. Thank you Ken Stevens for your Technology Serving Music !
https://www.catamps.com/products
There is a caveat to my subjective statement that my Ken Stevens' Convergent Audio Technology (CAT) SL1 Signature upgraded MKII to MKIII is a masterpiece. Subjectivism is based on or influenced by personal feelings, tastes, or opinions. With that in mind, the CAT MKIII after some tube rolling, allows me to achieve an incredible musical presentation at a price point that in my opinion, is sane. When it plays music, it sounds like music. It's transparent, textured, neutral, inexorably revealing, insightful and along with its pace, rhythm, attack and timing (PrAt), is more life-like than virtually any other preamp that I have experienced. I'm sure the build quality contributes to CAT's incredible performance. Both the main unit and power supply feel like solid masses. It is constructed like the proverbial Brick (expletive) House.This is due to their steel chassis and the liberal use of what Ken Stevens calls a "resistive damping compound" internally -- the blue stuff you'll see adhered to much of the main chassis's internal surface area. The steel and damping compound were chosen because they control resonance, something CAT takes to great lengths. Circuit boards are made of G200, a material that's 12 times more expensive than the substrate used for many of the circuit boards in other high-end products.
With regard to my system, my tube power amp is a VTL stereo 90 running 6550 Tung Sol power tubes with a pair of Valvo Blue Label pinched waist 12AT7 and a pair of Telefunken ECC801S signal tubes. The Cat SL1 Signature MKIII is a synergistic match created in Heaven. My Digital front-end consists of the Mark Levinson 390S which I use as a transport that feeds a Monarchy NM24 Dac that uses 6922 vacuum tubes and is powered by a Monarchy AC-Regenerator. The CAT SL1 Signature MKII used 12AU7 tubes in the V6 and V7 line stage positions which was changed to 6922 tubes in the MKIII. According to designer Ken Stevens, the 6922 is a better input tube than the 12AU7, and allows the SL-1's noise level to be reduced from -92dB to -112dB (unweighted). Apart from the noise figure, the electrical specifications stayed the same: gain is within ±0.1dB of the Mk.II; there is no change in rise time, bandwidth, or slew rate. Still, Stevens says the sonic improvement is such that he seriously considered renaming the preamp the SL-2. I ran across this information from a stereophile review:The 6922 has been part of the SL-1's tube complement, but not in the line-input stage. The SL-1's design calls for the tube in this spot to have a plate voltage of 175V, and published 6922 specifications state that the maximum allowable plate voltage is 130V. The tube that Stevens now uses as the line-input tube is made by Sovtek in Russia, and has the European designation of E88CC. Although labeled 6922, it has—as Stevens discovered when reading the instruction sheet packed with the tubes—a maximum plate-voltage spec of 220V, well within the SL-1's requirements. To accommodate the new tube, the gain was padded down. There are no other circuit changes. My Analog front-end consists of a Thorens td 126 MKIII with a Denon 103r cartridge that feeds my Allnic AUT 2000 step up transformer which feeds the CAT's phono inputs. Last, but not least, my system has a Revox a77 High Fidelity reel to reel tape player.
When it comes to tubes, my tastes prefer NOS vacuum tubes. Ken's SL1 Signature MKIII is supplied with (Sovtek) 6922 and (EI ) 12AX7 tubes. I subsequently rolled a pair of Telefunken E88CC in the V1 and V2 positions and a pair of Telefunken ECC83 smooth plates in the V3 and V4 positions of my Phono Stage. I left the Sovteks in V6 and V7 because of the plate voltage issue but rolled a pair of Mullard MC-1s in the V8 and V9 positions in the Line Stage. You would have to hear the musical presentation with this tube combination.
In conclusion, my personal feeling is a "Masterpiece" is the work of an artist who has been absorbed by the spirit of his/her times and can transform personal experience into a universal one. Masterpieces make us forget the artists, and instead direct our attention to the artist's works. We may wonder how a particular work was executed, but for the time being, we are transposed, so deeply brought into this creation that our consciousness is expanded. Thank you Ken Stevens for your Technology Serving Music !
https://www.catamps.com/products
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