After I wrote the article What's So Irresistible About a Single-Ended Triode (SET) Amp? I started to receive scores of emails from readers asking me if I was aware of a company located in Brimfield, Massachusetts, called AricAudio and its CEO/Designer, Aric Kimball. Each reader had purchased either a tube preamplifier or SET amplifier from this company and raved about the build quality, performance level, and reasonable pricing. When I did my research into Aric's work, it was apparent that he was an innovative tube designer and a master craftsman who handbuilds high-level gear that competes with much more expensive tube equipment in today's market.
After a conversation with Aric regarding which SET amplifier in his line I should review, we decided on the Transcend Series KT120 SE stereo amplifier, which retails for $2,350. It is one of the few SET designs that uses KT88/KT120/KT150 power tubes and can be run in either SET or Ultra-Linear mode. This allows you to get 9 to 11 watts in SET mode, depending on what power tube you use. If you need more wattage to drive your speakers with certain types of music, you can flip a toggle switch to put the amplifier into Ultra-Linear mode to get 18 to 22 watts per channel. These power tubes are all current stock and are very reasonably priced compared with the NOS tubes often used in SET designs. It turned out that my favorite pair of tubes in this amplifier was the JJ Blue Glass KT88, which can be purchased for less than $120.
The KT120 SE is also a headphone amplifier with a volume control, along with a toggle switch to disconnect your speakers when you are using your headphones.
The KT120 SE arrived in pristine condition because the packaging contained high-quality internal bracing and fillers to safely protect it. This amp is a very handsome-looking piece, with great build quality. It has a height of three inches, a width of eight inches, and a depth of 12 inches, and it weighs just 35 pounds. The compact size made it easy to move between my two systems. The amp has walnut side panels with a black chassis that's designed in the so-called "battleship style" of classic tube gear. This means that the KT120 SE's three massive high-quality Hammond transformers are arranged on the very back of the top chassis, with the power and 12AT7 input tubes in front all in a row. You also find a classy-looking badge with the amplifier's name and the AricAudio logo engraved between the power tubes.
On the front plate is the volume control, headphone input, and a variable negative feedback control. You can run the amplifier with no negative feedback at all, which I felt produced the best performance regardless of which power mode the amplifier was in or what speakers it was driving. However, this feature gives you the flexibility to dial-in what you find the most musical or pleasing to your ear. Around back is where you'll find one pair of RCA inputs, an IEC input, a power on/off switch, the switch that turns off the speaker terminals when using the KT120 SE as a headphone amplifier, and two sets of either four-ohm or eight-ohm speaker-wire terminals.
I fed the amp signals from my Micro-ZOTL preamplifier; the rest of the upstream equipment was a CEC-3 CD transport, a Concert Fidelity-040 hybrid DAC, a Running Springs Dmitri power conditioner, MG Cable reference silver and copper wiring, and Audio Archon power cords, all placed on the Tomo rack/footers by Krolo Design. The KT120 SE amplifier drove the following speakers during the review process: Tekton Design Double Impacts, Tekton Design Ulfberhts, and MartinLogan Motion 15s.
My first selection was the album Standards Rican-ditioned (Zoho) by the great jazz conga player Ray Barretto, which contains classic jazz compositions with a Latin/Salsa flavor. This music is complex, with dazzling counter rhythms and rich timbres created in the horn section. The KT120 SE's rendering of the tonality/timbres was rich and accurate. The overall tonality had a super-easy liquidity that allowed the music to flow into my listening space, yet the drive of this music was all there, which made it hard not to tap your toes to the beat. I have never heard a KT88-based SET amplifier before, and I found it quite striking that this amplifier had the tonal beauty of 300b-/2A3-based SET designs but with more power and overall dynamics.
The next selection was Jimi Hendrix's Voodoo Soup (MCA) to see how the KT120 SE would handle the bite and sizzle of Hendrix's killer guitar playing. Every little nuance of Hendrix's bending, plucking, and hitting of the strings came through with the right amount of distortion and decay. This showed how quiet and transparent the KT120 SE amplifier was, along with its great micro-details that just pop up effortlessly. For an SET design, this amplifier has excellent speed and resolution.
One of my favorite tenor saxophonists of my generation (I am a Baby Boomer) is Scott Hamilton, who is a total master at the art of ballad playing. He brings a luscious, beautiful, deep tonality to the music. His new album, Live at Pyatt Hall (Cellar Live), is a reference-level recording, particularly in how it captures the ambience of the hall and the space/air between the players. Listening to this album through the KT120 SE--in SET mode with the JJ KT88 Blue Glass Tubes with no negative feedback--was a magical experience in that I felt I was in the Pyatt Hall venue surrounded by other audience members.
One of the strongest virtues of a world-class SET amplifier should be how it reproduces the midrange frequencies, along with how it replicates the human voice. My last selection was the great jazz diva Stacey Kent's album A Fine Romance (Candid) to see how the KT120 SE would handle this last sonic frontier. I have had the pleasure of hearing Ms. Kent live on a few occasions and have a good take on her voice. The illusion that this amplifier created for this great singer was that she was standing in the middle of my room, with world-class, three-dimensional imaging/palpability, along with the gorgeous color of her voice. The sound was very striking and totally enjoyable.
• With the KT120 SE amplifier, it's like owning two different tube amps in one chassis. In SET mode it offers a tonality rich, beautifully intimate presentation; and, in Ultra-Linear mode, it sounds like a more direct, powerful Push/Pull design. All the tubes that the amplifier uses to achieve this high level of performance are very inexpensive and easy to purchase.
• The amplifier also provides a reference-level headphone amp that has the ability to drive any headphones on the market today because of the amount of current it can provide.
• Because the KT120 SE has its own internal volume control, it can be used without the need for an external line-stage. It sounds great as a standalone amplifier and just goes to even a higher level of overall performance when driven by a quality preamplifier.
• The KT120 SE Amplifier has no theater bypass and only one RCA input.
• It does not come with a tube cage to protect pets and children from the hot-running power tubes. The amp also runs very hot; therefore, it cannot be put into a closed rack.
Comparison and Competition
To find an SET amplifier that I've used that competes with the level of the Transcend Series KT120 SE, I had to jump up considerably in price. The first amplifier is the terrific-sounding Canary Audio SET 300b M-80 mono block, which retails for $9,000/pair. The Canary amplifiers might offer a tad (and I mean a tad) more bottom-end extension and a smidge more overall liquidity, but it's really close--and they sell for $6,650 more.
The second amplifier is the Sophia Electric SET 300b 91-01 mono block that retails for $5,000/pair. In this case, the KT120 SE's timbres/tonality were the equal of the Sophia Electric amps while offering more powerful overall micro-dynamics and a larger, more airy, and accurately layered soundstage.
Because of my experience with the AricAudio Transcend Series KT120 SE amplifier, I now have to put Aric Kimball on my short list of innovative designers of world-class tube designs. His company uses the finest parts, and the products are hand-built with care and high quality. You can take any of his standard models and customize them for a reasonable cost increase, or you can discuss with him some build project that would revolve around certain tube types or circuit designs.
The KT120 SE's performance offers the best of an SET design. The beautiful colors, liquidity, air, and bloom are all there. Because of the choice of power tubes, you also get the bass control and overall macro-dynamics that you usually only get from more powerful push/pull tube designs. I had never heard a KT88 based SET design before reviewing this amplifier, and I found it quite amazing how closely it competes with SET amplifiers using the much more expensive legendary NOS 300b and 2A3 power tubes. When you add into the mix you that can run the KT120 SE amplifier in Ultra-Linear mode for more power-hungry speakers, along with having a great headphone option, the KT120 SE's asking price of $2,350 is quite a bargain.