Kondo–Audio Notes Overture Integrated Amplifier
What a Wonderful World
It was back in March of 2010 when I reviewed the MasterSound Final 845 mono amplifiers. These glorious beasts of amplifier design opened my ears (and heart) to the wonderful world of tubes. MasterSound showed me what tube magic was all about when done correctly. Since then, I’ve been on a sort of quest, keeping my ears and eyes open for tube amplifiers.
At the 2011 CES, I was introduced to the Overture integrated amplifier from Kondo - Audio Note. This room seems to always produce a superb sound. The Overture drove a pair of Kondo Biyura loudspeakers effortlessly. It’s an entirely new design and their first push-pull (integrated) employing EL34 tubes. There’s a purity and naturalness that's magical whenever I hear Kondo electronics. In fact, I was so taken by the sound that I immediately started wondering how the Overture would perform in the comfort of my listening room. I met Charles Tse from Kondo - Audio Note and he informed me that 2011 would be the official launching of the Overture integrated amplifier. I asked Tse for the opportunity to review the Overture. He responded positively and promised he would do his best in arranging a review sample. But a few months passed with no Overture. So I emailed Tse inquiring about its status. Unfortunately, I was informed it would be a while due to a small series of production runs in Asia that sold out immediately. This is some news considering the Overture serves as the company's most affordable integrated amplifier at a cool $41,558.00.
Good news. At the 2012 CES, Charles Tse informed me that I would be receiving the Overture integrated amplifier shortly after the show. During the second week of the February, New York high-end retailer, Bob Visintainer of Rhapsody Music & Cinema - and Kondo - Audio Note’s newest US distributor, contacted me. The Overture had finally arrived. It seemed like an eternity but just a few days later Visintainer told me that I could come by his store and pick up the Overture. Fortunate for me, I live only 15-minutes away from his mid-Manhattan loft. The following day I dropped by and surprisingly got a chance to hear the Overture driving a huge pair of Avantgarde Uno horn loudspeakers and, as I had expected, the sound was absolutely wonderful. In fact, it was a personal best for me in terms of hearing a pair of Unos. I couldn't wait to box up the Overture and hail myself a cab back to my Battery Park apartment.
The Overture is an integrated amplifier based on the pentode EL34 - a first application for Kondo - Audio Note. It’s a push-pull pure class-A design, using two EL34s per side to produce 32 watts per channel. Dual 6072 tubes are used for the input stage and a pair of 12BH7 tubes are used as drivers for the EL34 power tubes. The Overture is a high bandwidth circuit design and its first stage and the driver stage are both direct coupled circuits. Pure silver foil capacitors are used as coupling in the output stage. According to Kondo - Audio Note's president Ashizawa Masaki “..we aimed to make the entire circuit into low impedance so the transparency and the direct sound is achieved." Constant Current Biasing (CCB) is a newly designed circuitry that was adopted for the output stage. The CCB prevents music signals from flowing into the bias adjustment and maintains the signals purity and integrity.
The output transformer is a UL connection with only a 3 dB negative feedback (NFB) employed to get the best balance of low distortion and good dynamics. The high reserve power supply is constructed with a choke coil and a large capacitor group. After the ripple filter stage, the decoupling capacitors are further arranged to serve left and right channels independently. In addition, it’s equipped with 500uf/ch in the input stage of the left and right channels; achieving high headroom and wide bandwidth. Furthermore, internal wirings are skillfully arranged so that the shortest paths and best performance are obtained.
All parts are carefully chosen after many hours of listening tests and meticulously constructed by artisans. Kondo - Audio Note Kondo uses nothing but the very best custom-made quality parts employing Kondo’s signature handmade silver foil capacitors and silver lead resistors. These pure silver foil capacitors were the first to use pure silver foil as electrodes. They are specially designed to prevent the potential oscillation with the foil, which can easily generate muddy sound when the signal surges from low to high and are used as couplings in the output stage. Custom made choke and output transformers and power transformers are produced by ISO Tango. The SSW silk silver wires are used in order to suppress any unwanted vibration. Natural silk is used and twisted around the silver conductors. This works as an insulating layer between the silver wires and the exterior PVC jacket and KSL-Vz II shielded cables are used throughout.
The Overture is single-box, made with a low-key, high-quality finish with an aluminum and copper chassis. They are applied for specific purposes. Copper plate is used in the middle of the chassis for an important contribution to vibration control as well as good grounding. The layout of the front panel is elegant and simple. It employs only three rotary knobs. On the left is a power switch which has a smooth silent feel and on the right is two larger rotary knobs and a function selector knob with four inputs and a volume control. The rear of the Overture reveals four sets of beautifully finished, high quality input sockets; and to the right there are two vents below. On the left there are meticulously finished Teflon 5-way speaker binding posts. One is neutral and the others are for either a 8 or 4 Ohm tap (I chose the 8-Ohm tap with my loudspeakers). On the right bottom there is the IEC plug. The chassis is well ventilated on the front top cover while the front face-plate utilizes horizontal air vents.
My system consists of my long time reference: the Consensus Audio Engineering Conspiracy loudspeakers powered by the Karan Acoustics KSA 450 amplifier, the Karan Acoustics Reference Preamplifier, and the new superb sounding reference Pi Greco Sinfonia CD player from Italy. For this review the system was connected with all Kondo silver cables. Their model KSL-SPz silver speaker cables, model KSL-PLz silver interconnects and KSL silver AC power cords were used throughout.
Incredibly, right out of the box, I was impressed. The sound had a captivating nature to it just as I heard in Vegas. The Overture sounded easy and free of grain and strain. Normally I would usually allow for settle and burn-in for a week or two before any serious listening would take place. This time was different. Happily, all the Overture required was 15 about minutes of warm-up for the circuit and the tubes to shine [as the manufacturer recommended]. The Overture was also dead quiet. I couldn’t hear hardly anything than a slight hiss even when I put my ears to the tweeter which is surprising considering this is a tube amplifier.
As much as I love listening to classical music on my system, the Overture has a magical way of conveying strings, woodwinds and vocals particularly from chamber and orchestral recordings. So much in fact, the Overture kept me glued to my listening chair, savoring my favorite works for hours. Strings sounded so natural and airy, it was as though I was listening in a larger acoustic venue. Moreover, the Overture possessed amazing resolution in its ability to reproduce ambient cues of the recording space, not just the instruments. With the Overture, everything sounded more vivid and realistic. Vocals, especially - are beautifully rendered.
One night I stayed up late listening to chamber music. I played through most of my two CDs of Beethoven Cello Sonatas & Variations by Jacqueline du Pre and Daniel Barenboim (EMI 724358624229) and two CDs of Piano Trio Opp. 1 & 97 Archduke by Daniel Barenboim, Pinchas Zukerman and Jacquline du Pre (EMI 094635079821). Via the Overture, both the piano and cello were stunningly presented with a touch more presence and image densitity than I’m accustomed to. The midrange and high-frequencies were purer sounding and displayed a greater amount of weight, density and bloom around them. As good as my reference Karan Acoustics separates are at reproducing music, the Overture rendered instruments closer to what I can only describe as the "the real thing."
The Overture’s effect on my system’s spatial performance is also worth noting. Tubes have a certain magic, creating a wonderful three-dimensional soundstage. The soundstage was as stunningly natural as it was wide and deep, stretching well beyond the Conspiracy's physical location; on some songs, beyond my listening room’s side walls. The Overture is very powerful with big dynamic swings. It sounds much more powerful than its modest power rating of only 32-watts per channel would indicate. The Overture drove the Conspiracys as loudly as I wanted without losing any of the integrity of the music. The Overture was able to scale the dramatics of the full orchestral crescendos with ease. Bass was surprisingly quick with full-bodied stops and starts. I noticed no dynamic compression whatsoever but did feel the Karan KSA450 did handle the Conspiracy's with greater bass output and control (at 250 watts per side, they damn well better). Listening to the Reiner/Chicago Symphony recording of Beethoven Symphony N0.6 in F, Op.68 “Pastoral” (JMCXR-0020) was very emotional. With the Overture, the performers, the stage, the space, the ambience, all were quite distinct. The fully orchestrated passages simply had more shades in their palette and the individual instruments were more correctly drawn than I am used to hearing.
Lastly, listening to one of my favorites, Rossini’s Sonate a Quattro (HMC 901776) by Ensemble Explorations, was compelling and moved me in a way unlike before. The notes flowed effortlessly and bloomed into a dense and complex mix of tonal nuances. There’s a rightness to the string timbres that had me listening for hours enjoying the sound and shaking my head in wonderment. The level of immediacy, tonal accuracy and dimensionality were more apparent. The authenticity of timbre and instrumental textures were both fuller and more vibrant. The experience is very reminiscent of the Reimyo KAP-777 and CAT 777 MK II combo I reviewed a few months ago. I fell head-over-heals in love with that system. The Overture, in my opinion, is equally stunning.
What I can say is that the Kondo-Audio Note Overture is an extraordinary integrated amplifier. The one word that constantly came to mind was: purity. I can easily say that it is by far the best integrated design I've heard and certainly competes with the best separates. If I wasn’t a reviewer I would buy the Overture in a heartbeat and simplify my system with fewer boxes and cables and call it a day, but unfortunately I need separates as a tool to evaluate components. Hopefully in the near future, when my finances allow, I hope to reward myself with the Overture as my reference integrated amplifier. Even if you’re not in a position to afford the Overture, you owe it to yourself to give it a listen. You won’t be disappointed. Very highly recommended! My hat goes off to Masaki san for creating a masterpiece. Bravo!
An interview with Kondo - Audio Note chief designer and president Masaki Ashizawa.
KK: Please tell us how you first got interested in audio?
MA: I learned to play electric organ when I was 5 years old in kindergarten. \ During elementary school, I learned other instruments and studied drum and guitar by myself as a hobby.I started to listen to a record audio receiver, the grandfather of the Boombox, with a turntable and found there were two different sounds from the left and the right speakers although only one needle was used. This was my first question about audio but unfortunately no one was able to answer it. In high school I was in a band playing drums mainly pop and rock music at the time and often recorded my own songs and playback. I was always keen on getting higher sound quality. This was the period when I started thinking seriously about audio.
KK: Tell us about your background in electronics. When did you first begin designing audio gear?
MA: I received my first electronic education in the technical college where Mr. Kondo was one of my teachers. He taught me most of my basic audio understanding. I became his apprentice after joining Audio Note and learned much more about music and audio and tube applications from him. I built my first speaker system for my home when I was in junior high school. My first serious audio project, which I designed and managed, was the KSL-M77 in 2000.
KK: When did you first begin working at Kondo - Audio Note and how did you get started?
MA: I was his student at the technical college and wanted to learn more from Mr. Kondo. After my first job working for a Japanese audio maker, I discovered myself filled witha strong passion to pursue the highest sound quality. I was very fortunate to be invited by Mr. Kondo to join his company and to be his apprentice. I accepted his offer and joined the Audio Note in 1990.
KK: How was it like working with Mr. Hiroyasu Kondo, the legendary designer?
MA: Mr. Kondo’s working style was very energetic as is his passion for music. He never hesitated to try something new; he was very opened minded,in order to understand the strength and the weakness of any subject or an idea. I was sometimes surprised by his “strange” requests or ideas. But they turned out to be surprises again when better performance resulted.
KK: Tell us about the company. Do you do all the designing or is there a design team?
MA: We have six members in our company including myself. We do everything from R&D to production. We design circuits, chassis, and our original components. Mr. Hirokawa and I are the main designers.
KK: How are you planning to carry on Mr. Hiroyasu Kondo’s legacy?
MA: I’m putting all of my time and effort into good audio design. Mr. Kondo taught me to be open-minded and to believe the importance of experimenting with everything to evaluate its characteristics. My passion to learn and to break through existing limitations is a core value of our company. We at Audio Note Kondo have learned much in our 36 years of experience with silver’s characteristics. We are going to continue to use silver as the key material for our products and fully express its sonic advantages. I am also trying to find a material which can surpass silver in all criteria when applying it to sound or audio. This is one of my missions and my ultimate goal.
Product Overture EL34 Push-Pull integrated amplifier
Rated Power 32W + 32W @1kHz, 1% THD
Frequency Response 6Hz ～ 140kHz (+0dB -3dB @ 1W)
Input / Impedance LINE (unbalanced)
RCA 4 pairs / 100kΩ
Output 4Ω, 8Ω
Noise lower than 0.5mV
Vacuum tube EL34 x 4
12BH7 x 2
6072 x 2
Power consumption 180W
Dimension 438mm(W) 201mm(H) 409mm(D)
*Due to the characteristic of the vacuum tubes used, it takes around 15 minutes to reach nominal sound quality and performance level.