ntroduced at the 2011 CES show in Las Vegas (USA), the Overture, an amplifier made by Japanese manufacturer Kondo (Audio Note Japan) caused quite a stir. Designed by Mr. Katsura Hirokawa and refined ("tuned") by Mr. Ashizawa Masaki, the current general manager of the company, was a proposal for the "novice" music lovers and audiophiles. As usual for luxury products, in this case a true high-end component, the quotation marks are necessary - these indicate a relativity of this term. With a price tag of 33,900 USD – that was the price of the Overture at the time – it is difficult to consider it a truly entry-level proposal.

One thing is sure - this was an unusual amplifier for this famous brand. The push-pull configuration of the output tubes was not new to Kondo. A novelty was the choice of tube - EL34 pentodes. This is a valve that by the vast majority of single-ended triode fans is considered "a cheap tube for the people":

"That's what's audiophiles keep constantly asking. At CES 2011, visitors praised the sound of the Overture as silky smooth, elegant yet with very clean and good dynamics. They thought that the circuit must be either Triode or Single Ended design (unlike other Kondo amplifiers Overture features a full chassis that hides tubes inside – ed.). Once we told them that they were listening to an EL34 Push-Pull circuitry, they were amazed about the quality level that EL34 can deliver. It was at that point we knew that we had reached our goal."

Kari Nevalainen, „InnerWorld Audio” 2012, more HERE

The goal was simple: to build an amplifier with the best possible performance, that would also be easy and enjoyable to use. And also a more affordable than the other propositions from the Kondo's range.

Overture II

As a result of these assumptions came the device at first glance similar to many others, such as the once famous Copland amplifiers. There is a silver front panel with two knobs and one switch, a black chassis that hides all the tubes and one LED. The only distinguishing feature on the front is the Kondo's gold logo, but a glance at the rear panel, and then a thorough inspection of the whole chassis and its interior allows us to understand what we are dealing with.

The quality of make and finish of Overture's chassis is delightful. The aluminum chassis plates are made with utmost precision - the screw holes on the top perfectly fit into the threaded holes below - something that is not as common as you might expect. The rear panel strikes with colors, red and gold - it is actually a thick copper sheet rather than copper-plated aluminum. A double plate inside hosting tubes and other components is made in a similar way. In earlier versions these elements were made of aluminum. Copper is coated with a layer of lacquer to keep it from oxidizing. The covers of flagship Kagura amplifiers are made in the same way.

The RCA sockets - four pairs of linear inputs - are silver ones, the same as used in OnGaku. The same are also the AN-BP3 loudspeaker connectors - large, easy to use and made of silver. There are separate taps for 4 and 8 Ω loads. Amplifier features also selected Kondo silver capacitors (a premium version with gold sticker), silver Ls-41 cables (standard version features the KSL-VzII) from inputs to potentiometer and custom-made resistors with silvers taps. The Japanese manufacturer chose the Alps HQPro potentiometer for the job, one the best available on the market.

Electrically the input circuit and phase inverter are coupled directly, without any capacitors. It features tubes rarely used in audio - 12BH7 and 6072, one per channel. Amplifier is delivered with tubes made by the Russian company Electro-Harmonix, but the Polish distributor has fitted the reviewed sample with sophisticated NOS tubes.

The output stage is a class A circuit operating in an ultra-linear push-pull mode. Designer decided to use a shallow (-3 dB) negative feedback taken from the primary windings of the output transformers. Output tubes operate in a fixed bias system - Masaki-san says there are no good enough high-voltage resistors on the market that can be used for cathodes in a “floating-bias” circuit. This circuit was developed in-house by Kondo and is called Constant-Current Bias (CCB). The music signal in it is separated from the voltage supply.

The amplifier delivers 34W of power per channel (this particular unit according to given specification delivered 32W) and features a wide frequency response. It is very heavy, so it uses five feet instead of four - the fifth one is placed under the transformers. This model does not feature a remote control. The make&finish is flawless. Together with a Kondo device a new owner receives a certificate signed by Mr. Masaki printed on a handmade cotton paper with his family seal. Also included in a box is an instruction manual and an amp specifications with measurements for the particular unit.

The Overture II was compared to the two and a half times more (including additional cables) expensive reference system consisting of the Ayon Audio Spheris III tube preamp and the Soulution 710 solid-state power amplifier. But also, I couldn't help it, to Kondo OnGaku, which I recently reviewed having it placed on top of the same Finite Elemente rack. In the latter one thing changed - I strengthened the top shelf by adding four Tablette Audio Franc Accessories feet, similar to those used in Amare Musica devices. The goal was to increase the maximum weight I could place on the rack.

The amplifier worked with my reference loudspeakers, Harbeth M40.1. These are rather difficult to drive due to a quite low impedance. The best SET amps, such as the Phasemation MA-1000 (Polish), and recently OnGaku, did a pretty good job driving them, but it was clear to me that there were some limitation. The Overture II drove Harbeths with more ease which suggested a better current efficiency.

During the test I used two power cables for the amplifier: either Acoustic Revive Power Reference Triple-C or Acrolink Mexcel 7N-PC9500. Interconnect and speaker cables came from Siltech Triple Crown series and Tara Labs Muse.

Recordings used for the test (a selec-
tion)

• Best Coast Jazz, EmArcy/Mercury M.E. [Japan] PHCE-3062, "2496 Spectrum Rainbow CD", CD (1954/1998)
• Western Electric 300B Vacuum Tube Sound, ABC Records HF1043, „HD Mastering”, CD (2012)
• Billie Holiday, Body and Soul, PolyGram/Mobile Fidelity UDCD 658, gold-CD (1957/1996)
• Mikołaj Hertel, Dźwięki dalekiego świata, GAD Records GAD CD 052, CD (2017)
• NOVI Singers, NOVI in Wonderland, Saba/Edel/Victor Entertainment NCS-10139, K2HD Pro Mastering CD (1969/2016)
• Perfect, Live April 1, 1987, Pronit/MTJ CDMTJ90406, 3 x CD (1987/2017)
• Sohn, Tremors, 4AD/Hostess CAD3403CDJ, CD (2014)

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Japanese issues available at

There is no doubt that Kondo has its own sonic signature. This is partly due to the materials and components they use, but it is also - at least I think it is - a result of giving a lot of thoughts to the question of what are the most important elements of the sound, which of them are worth focusing on. Achieving such results as Kondo has, takes many years and spending countless hours in a listening room to find answers to these questions. Measurements are certainly important, as they allow designers to eliminate all key errors from the start, but I do not know any audio products representing this level of refinement, that are based purely on measurement results. A key element of making sound the way they do are always hundreds of hours spent on assessing and fine-tuning the sound during listening sessions.

In short, Overture II sounds a lot like the OnGaku's amplifier. It does not sound the same but they both do share some common sonic qualities. It is primarily about tonality, as it seems to be this brand's key focus and it does make a huge first impression on most listeners. It is shamelessly warm. All music one plays using this amplifier sounds as if someone has turned up the heat in the room or as if the listener just took a sip of something stronger, something absolutely astonishing.

No, I am not exaggerating with these comparisons, this amp really offers THIS level of saturation and richness. The warmth in question is derived from the ingeniously conveyed texture of the sound and combining into one all of its basic components and harmonics. But it is also supported by the emphasis in the lower midrange / upper bass area. This was done extremely skillfully, with class, so it doesn't even feel right to call that a “coloration” or modification of the sound. One can feel that the range is not "flat", that there is something “there”, but that conviction is the result of a sound as a whole, not of its elements. The point is that there is no chance to analyze the sound properly and pinpoint what exactly is different.

The warmth and emphasis I am speaking of are siblings of emotion. After all, this is a key aspect of music presentation and it should be emphasized, right? Overture II is like a small generator of emotions that lead listener with a steady hand from one recording to the next. It does not matter what record it is - each will be treated in the same way. Which of course leads us to the question regarding differentiation. I don't have a problem with answering it, but the answer must be preceded by the phrase "it depends".

On one hand, we can discuss sound quality and then there is no doubt that we are talking about the beauty that places this amplifier among the best ones there are. So perceived, it conveys what's best in a given recording. On the other hand, taking a position of an impartial observer, we can easily point out that this type of presentation involves also omitting some shortcomings of the recordings, their problems of both philosophical – such as the choice of recording techniques, the way of mastering in general - and technical nature – the same as before but taken literally. Overture II is also not as resolving as my reference system, much less the Ongaku.

Let's take, for example, the latest remaster of NOVI Singers album NOVI in Wonderland. It was prepared by Victor Entertainment, using the mastering tools (and presses) they referred to as "K2HD Pro Mastering". The most important are the voices of the singers, it is clear. Kondo's amplifier didn't just convey that, but emphasized it. Played by this amplifier they were actually rich, had a large volume, and so sounded incredibly realistic. Although warm, it is not a dark sound (the reference system is darker). The accompanying instruments were very well-structured and well fitted into this vision. But those voices ... Overture II perfectly presented what the whole K2 process is about, its strengths and weaknesses. The former are: density, richness, an amazing richness; the latter are: warming the sound up, and an emphasis on sustain at the expense of decay phase of the sound.

The same happened again with Billie Holiday and Sohn's albums. In this case the amplifier proved that these were quite different types of recordings, of different aesthetics. So there it is – a good differentiation. After some time I concluded that when it comes to presentation of timbre, tone in all of their shades and types, Overture II is sufficiently resolving and analytical. I mean, it's not an ultimate resolution, it is a specifically “voiced” type of sound, but on a different level than a warmed up sound offered by devices from, say, 5000 or 10 000 PLN price level. This is not about covering up the own problems of the amplifier, but rather about emphasizing qualities of each recording.

The stronger “presence” of the lower midrange and upper bass translates into a large volume of sound that I've already mentioned before. It will always be a powerful and exciting presentation with lots of sound between the loudspeakers, without any discontinuities and holes. It will fill the whole space between the speakers and pull us into it, bringing the foreground closer to the listening position. Unlike with most tube amplifiers, in this case it does not matter what kind of music we want to listen to because Overture II handles almost everything equally well. Even Vader's extreme music was exciting and energetic.

The dynamics of the device on an absolute scale is lower than one of my reference system, physics can not be cheated. In spite of that, subjectively, the discs, that when played on a more precise system, didn't sound too well, became interesting with Overture II. One example may be Perfect's Live April 1, 1987, very nicely remastered in analogue domain by Damian Lipiński. I have this material on the original LP and I must say that listening to it has always been a challenge. Remaster improved all aspects of this recording, straightened it all up, but one thing remained unchanged – the dynamics is still very flat.

The Kondo amplifier played this record, in short, better than the reference system. I could still hear the problems of this recording, but the ability to create beautiful three-dimensional images made the guitars finally come out of the background and the gave vocals a strong foundation. Only the drums remained in the background. On the other hand when I played a high quality recording I could clearly hear a dizzying array of sounds, coherence, harmony, depth. The latter concerns more tone than space aspect. The Overture II delivers music effortlessly, in a very good, impressive way, but within certain sound aesthetics. Of course, it's not the same as OnGaku as it is one of a kind.

Also differentiation within soundstage is done using tone rather than palpable imaging. The amplifier shows everything legato, combining rather than dividing elements. It slightly shortens the reverb (acoustics), because the focus is on the main tone (sustain), where the most energy is. Everything is presented close to listener, tangible, intimate. As I've already said, this presentation does not limit our choices of music to jazz, or small classic pieces /ensembles such as baroque. This is an ability that every tube amp has, intensified at the very top: the amplifier delivers more powerful, louder, more dynamic performance than its specification might suggest. Even with such difficult speakers as the Harbeth M40.1 Overture II with dynamic, powerful electronic and rock music sounded better, more energetic than many solid-state amps with an output of 100+ watts.

One of the consequences of the choices adopted by the designers is a lesser than with a powerful solid-state amplifier, but also OnGaku, differentiation of the lower range. Listening to e.g. infrasonic sounds on the Anja Garbarek Briefly Shaking album, or precise pulse of the lowest bass notes from the Sohn's disc, it was easy to come to two conclusions: the amplifier does not extend anything, does not let anything go, and at the same time, at the very bottom, below 100 Hz it delivers much less differentiated sound than above this frequency. And so we've reached the physical limits of tubes in general and EL34 in particular.

But why pentode?

The question that comes automatically to mind even before listening to such an amplifier, i.e. a push-pull featuring tubes other than triodes, is whether it would make more sense to buy an even less expensive SET. First of all - it has to be a personal decision, we are talking here about an amplifier that is an equivalent of the best tailor made suit. If it is our "size" and style then there is nothing to think about, just buy it and stay with it forever. On a more general level, the question can concern the technique itself, i.e. whether the pentode push-pull is capable of delivering better performance than a SET counterpart.

I do not know how to answer this question because I'm not objective - in a sense that I really don't care much about technologies because I've heard my share of poor sounding SETs, many crappy turntables, and so on, so I'm pretty sure that a particular application of the technology is much more important than the technology itself. When used properly, particular application may deliver performance that other applications of the same technologies are not able to provide. And that's the case with Overture II and its push-pull circuit. It won't offer you such a perfect insight into the recording as the best SETs, nor equally perfect holography of presentation. On the other hand, this is a more forgiving amplifier, and therefore more versatile. While SETs are often "purpose-oriented" amplifiers, requiring the proper easy-to-drive loudspeakers (and those usually have their own problems) and targeted selection of recordings, a well-built push-pull allows user to forget all such problems and to use speakers of user's, not amplifier's, choice.

Summary

The Overture II amplifier shows user a better world. It belongs to this type of audio components that make our world more beautiful. Because it represents an absolute top-level performance, these are no lies, no omissions, but rather intelligent choices. The amplifier offers a warm, large in scale, beautiful sound. It is surprisingly universal, i.e. listening to the Gothic compositions performed by The Hilliard Ensemble user will experience the same level of excitement as during the first listening to Ed Sheeran's Divide. Presentation will be mostly about emotions, energy and coherence. This is a beautiful device that makes its user to forget about its technical aspects and just focus on music. And I believe that this is what we all are looking for, aren't we?

Overture II is an improved version of the Kondo (Audio Note Japan) Overture model, introduced in 2011. The differences from standard version include:

• Ls-41 input wires instead of KSL-VzII,
• selected silver capacitors (gold label),
• silver speaker connectors AN-BP3, the same as used for Kagura and Ongaku,
• copper chassis (similar to ones used for G-1000, M-1000 and M-77),
• copper rear panel finished with lacquer (similar to the cover of Kagura).

The improvements were introduces as results of hundreds of hours of listening sessions. Also passive elements were carefully selected - potentiometer, resistors, capacitors, etc. As Mr. Masaki-san said, "these changes have significantly improved the sound quality."

The amplifier features two knobs – volume control and input selector. The first one is connected directly to the potentiometer, bolted to the front wall. This is a powerful, large Alps HQPro potentiometer available only in Japan. Its solid, brass housing stabilizes it mechanically. Same as other potentiometers of this class, eg TDK Type C (Tokyo Ko-On Denko), used in Octave Jubilee Pre preamplifier, it is not controlled by the motor. It is connected with input on the rear panel with quite long sections of silver Audio Note Ls-41 interconnects. The mechanical input selector was moved to the rear of the device, and the knob is connected with it using a a long spindle.

The inside is divided horizontally into two parts. On top there are tube, output and power transformers, and power supply choke. Transformers in the previous version were produced by another Japanese specialist, ISO Tango, but those used in the PM-2 version bear Kondo's logo. This was explained by Mr. Ashizawa Masaki:

Copper […] delivers its best audio performance in its high purity form. Applying annealing will oxidize it easily, which eventually lowers its purity. Therefore we did not apply any annealing to the copper used at the Overture transformers. But don't worry, winding skills is another very important factor in making transformers, and all transformers in Overture are skillfully hand-made by ANJ. This is at least as significant a feature than the wire material."

Kari Nevalainen, (see HERE)

The passive components are installed underneath. They were soldered on excellent pads, shielded with copper sheets, but using the point-to-point method, utilizing the gold-plated auxiliary bolts. Silver capacitors are wound up manually in Kondo. They are designed to counteract oscillations on lining, that distort sound at fast transitions (transients).

A large battery of capacitors with a total capacity of 500 μF was used in the power supply section. Once the voltage has passed through choke, it is filtered separately for left and right channels. All capacitors are bypassed using high quality polypropylene capacitors (they are better at high frequencies). They were also used for tubes' cathodes. The rectifier bridge was made using high speed Shottky diodes.

Specifications (according to manufacturer):

Power output:
34 W + 34 W/1 kHz, 5% THD
Frequency range:
8 Hz – 100 kHz (0 dB, - ­3 dB/1 W)
Noise: 0,5 mV
Input impedance: 50 kΩ
Tubes:
4 x EL34, 2 x 12BH7, 2 x 6072
Power consumption: 180 W
Dimensions (W x H x D): 438 x 201 x 409 mm
Weight: 26 kg