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Integrated amplifier

Haiku-Audio | „Haiku Custom Works”

Manufacturer: HAIKU-AUDIO
Price (in Poland): 16 600 PLN

Contact: Wiktor Krzak
ul. Ślusarska 9 (Zabłocie)
Kraków | POLSKA


Provided for test by: HAIKU-AUDIO

HAIKU-AUDIO is a Polish company with its headquarters based in Krakow, specializing in the production of audio amplifiers. Established in 2012, it took its name from the type of output amplifier by company called Talcomp. The name of the circuit refers to its simplicity and effectiveness, a harmonious combination of content and form. The owner of Haiku-Audio and its chief designer is WIKTOR KRZAK. The name of the company, the name of the particular model, but most of all the approach to its products meant that the Polish device had to be included in the issue dedicated to products from Japan.

iktor is a musician - a bassoonist - playing both symphonic music and experimental forms. But for years he has also been an active audio amplifiers designer. He started in 2002, but the company was not founded until ten years later, when its founder found his own path. Initially, the products with the Haiku-Audio logo were available mainly in the form of kits, in various stages of assembly. With time, finished products became dominant position in the lineup and today they are the basic activity of the company.

When we look at the offer of this Krakow-based company, we will see that the designer's passion, or continuous striving for improvement, a need to try new solutions - that all of this culminates in a separate series of products called "Haiku Custom Works". We can find in it short series, often one of the kind products, which are something like "special products", using NOS type tubes, high-end components, even more sophisticated circuits, and so on. In other words – elements that in a bigger scale production are simply too expensive to use and using them make it impossible to maintain repeatability of products.

| Relativity theory in practice

When during the Audio Video Show 2018 I saw the new Haiku-Audio amplifiers called Origami - I was speechless. It was a tube devices that could well be made in Japan. It was about both the external design and the quality of workmanship. There were two amplifiers utilizing the EL34 and 6550 tubes, and each of them was available in two versions: integrated and as separates. For the latter, the division was made in a quite unusual way, because it was not a preamplifier or power supply sections that were placed in separate chassis, but the input selector and attenuator.

We agreed to test this amplifier, but without setting a specific date. We finally managed to meet beginning April this year, I mean Wiktor and me. Which, in the experimental way, allowed us to prove the theory regarding the relativity of time and space - the route from the current headquarters of the company on Zabłocie Street to my place takes 18 minutes by car, via Zakopianka, and an hour on my feet, through Kalwaryjska street. While carrying an amplifier it would probably take twice as long, because one would have to make a stop on the way and rinse one's throat in one of the pubs near the Bernatka footbridge.

When Wiktor, along with the company's representative, began to unpack the amplifier, I felt a slight twinge, but I did not know what was going on. And even the 300B tubes put in the sockets by Wiktor did not knock me out of the stupor - I looked and did not see. It turned out that somewhere along the way, with time, not only he and the space were relativized, but also the object of the test. Ultimately he delivered for assessment a device, which had just been assembled with the 0001 serial number, the integrated amplifier called SEnsei 300B.

Owner and designer

WIKTOR KRZAK: Have you heard that Revox is launching a new tape recorder? - Unfortunately, it will not record, but only play music…
WOJCIECH PACUŁA: That's not an issue for me – if you want to records on reel-to-reel you have to buy Nagra, or Revox PR99 III and at the cost of just a few thousands you'll become an owner of a professional equipment. While the Revox, or Thorens – as they are also about to release a tape recorder – are meant to to play already recorded copies of master-tapes.

WK: But the times have changed and we can choose from many available devices today, right? Until recently, there was just a CD player, few used LPs, but until few years ago nobody even thought about tapes...

WP: The 300B single-ended tube amplifiers can be compared in this context to tape-recorder, can't they? WK: Actually, yes, one could say that :)

There are more and more tube amplifiers n the market, hence soon it may not be a niche market anymore. How is the SEnsei different from all other devices available on the market?
On the one hand, this is a sum of all my experiences resulting from studying and listening to other amplifiers. That's why I gave it this name - I've been watching the masters. On the one hand, there is Kondo and Audio Note, on the other Verdier - the latter is sort of my private tube world guide. This is absolutely not a copy of any of them, but a result of my conclusions.

There are a few things in it that I finally managed to do and implement. For example - in this amplifier there are no semiconductors at all, not a single one. The 300B heating is managed with an alternating current, which is a rare solution.

Haiku-Audio's workshop in Krakow's Zabłocie. 30 years ago, in the same place, in Unitra-Telpod factory, during my school's workshops and assembled potentiometers and capacitors…

And there is no hum?
No, none. Only while switching on you will hear a not so loud crack coming from speakers and this is the only inconvenience of such a solution. There is nothing to be afraid of :) There are two gain stages for small signals and a third output stage. The feedback is used differently than in the amplifiers - and, that is most important, there is a NFB. It is not parallel, and serial, applied in a completely different way.

How does it work?
This feedback is sourced form a separate tap of the output transformer. This is a SE circuit, where the NFB does not include the entire amplifier. I did want it however, to loose control over the performance. This circuit reacts differently to the sound than a regular one, because it does not harden the sound as the voltage NFB does.

I can see only single loudspeakers out – isn't it a problem when using speakers of different impedance loading?
No, it is not a problem at all, as the amplifier operates in the 4 to 8 Ω range, while delivering 9 W output without any problem. The secret of such a solution is the power supply. I decided to use a GZ34 rectifying tube and a large choke, that you can see in the front. The filter is a classic "Pi", but an improved one - recently I took it as a challenge to design power supplies with the smallest possible capacity. And this requires very large chokes – in this case it is as big as the output transformers. It also features a very good metal and it is the main filtering element. In my opinion, such a circuit behaves better tonally.

Of course I used spatial assembly. As for novelties that I do not use in any other products, there are new bakelite sockets for tubes, that have made a come back recently. They are cut out on CNC machines, the legs are grabbing mechanisms, etc. Bakelite is closer to the spirit of the past - this amplifier is supposed to be a bit nostalgic. I did not try to achieve some particular measurements with it. Obviously, the amplifier must be resistant to aging, it must not have any hum, noise, etc., but this is not my goal. The goal is to get listener closer to the music, to other times, to create the right mood.

The 300B delights when it comes to chamber music - that's when wonderful things happen. For example, when we listen to a string quartet, when the musicians enter together into a small room. When real acoustics are recorded together with music, to hear that you can not have anything better in your system. You do not pay attention to the fact that there is a crack on the record, or that the bass is somewhat unclear - it doe

What speakers do you use with these amplifiers?
I use my own design that has no name yet, it is not commercialized. This is an old project, from the time when I worked at Talcomp. It was there that we designed loudspeakers together with the team, which are still in the development phase :) And they are my reference speakers. I am still testing some drivers - we make our own bass drivers. There is a man here, Irek, who himself extrudes the suspension; the membranes are from Tonsil. My columns have 90.5 dB efficiency at 8 Ω.

| SEnsei 300B SE

The output | As I said – I threw up my hands. The problem was not the amplifier itself, but its output 9 W for my Harbeth M40.1 speakers is definitely not enough. Although they are quite easy to drive, have a "friendly" impedance, and I sit quite close to them (every additional meter of distance from speakers requires doubling the amplifier output to get the same volume level), their sensitivity is not particularly high and experience teaches that all their advantages are shown with high output amplifiers, preferably solid-state ones. And the SEnsei 300B SE amplifier offers just 9 W per channel.

I said my piece and - it might have seemed - we ended the same matter. But we looked at each other with Wiktor and I promised that I would give it a try anyway and if I think that the amplifier can not handle this loading, we will think about some other device for the test.

As you can see, I did the test. The latest Haiku-Audio amplifier proves something that Kondo crew, Jarek Waszczyszyn and other key tube amplifier designers have always known: output power is one factor, and current efficiency is a whole different one.In this case we are dealing with an oversized power supply with small capacity, but also a powerful choke, not much smaller than the output transformer itself. And the latter is surely not a small one.

Design | Both, the power supply transformer and the choke, as well as both output transformers, were screwed on the top of the device. This is a classic design for tube amplifiers, known since the 1940s, where all transformers and chokes, as well as tubes, are mounted outside the chassis, which provides them with better cooling and shields the audio circuits.

SEnsei 300B SE is a tube amplifier, with a tube power supply. It operates in Class A SE, i.e. single-ended. This means that the entire signal, both of its halves, are amplified in one gain element - starting from the E802CC input tube, through the ECC81 driver, and ending with the 300B power tubes. All tubes, including the GZ34, that is a full-wave rectifier, come from the Slovak company JJ Electronics (the Japanese Leben also sources tubes for its devices from JJ).

The electrical circuit is very simple, but it is a sophisticated simplicity. To be simple and functional at the same time, you have to know what you can give up. There are capacitors from the Polish company Miflex inside along with Ohmite resistors and CMC speaker connectors. The assembly is spatial, i.e. point-to-point, without any printed circuit boards, but with auxiliary elements.

So, here we already have two main features of this device: extensive, not very typical power supply, as well as the signal's path. Equally important, maybe even the most important, are the output transformers. They look inconspicuous, but they conceal the patent applied by Wiktor in the SET amplifier for the first time, and previously known from the QUAD II amplifiers; Mind you - QUAD II were push-pull amplifiers.

| Thesaurus

Class A = parameters of amplifying elements (tubes and transistors) are described by means of static characteristics, so-called curves. Depending on the point on the curve, the amplifier operates in one of four classes: A, AB, B and C - the first three are used in audio. Class A allows you to amplify the entire signal in the most linear part of the characteristic, but with very large energy losses, emitted as heat.
Triode = is an electronic amplifying vacuum tube consisting of three electrodes inside an evacuated glass envelope: a heated filament or cathode, a grid, and a plate (anode)
SE = Single-Ended, type of circuit in which the whole signal is amplified by a single element in a non-symmetrical circuit
PSE = Parallel Single-Ended, it is still a non-symmetrical circuit, but with couple elements operating in parallel
SET = Single-Ended Triode, which is a triode operating in a single ended circuit
DHT = Direct Heated Triode, type of a tube in which a heater is a part of a cathode
300B = direct heated triode (DHT), developed in 1933 by General Electric, introduced to consumer market in 1937. It provides maximum 9W output
ECC = designation of low power tubes with a noval (glass) base, where 'E' means a 6,3V heating voltage, and 'C' means a triode; in this case, two triodes, because it's a double triode

The point is that there is no global feedback loop in the whole amplifier. Instead, the feedback signal is sourced from one of the secondary windings of a multi-section output transformer, which is connected by a split load technique to anode's, grid's and power tube's cathodes paths.

The amplifier features an aluminum front with two large knobs – volume control and input selector. There are four inputs. Amplifier features single loudspeakers connectors - Wiktor ensures that the amplifier's operation is stable in a fairly wide range of impedance load. The on/off switch is placed on the right side of the device. The amplifier does not feature remote control. It's been one of the hallmarks of the Haiku-Audio designs for many years. Today you can order different versions of devices, also including a remote control.

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  • Recordings used for test (a selec- tion):

    • Beethoven, Complete Sonatas for piano & violin, wyk. Isabelle Faust, Alexander Melnikov, Harmonia Mundi HMC 902025.27, 4 x CD (2009)
    • Bill Evans, Bill Evans At The Montreux Jazz Festival, Verve /PolyGram Records 539 758-2, „Verve Master Edition”, CD (1968/1998)
    • Bill Evans, Bill Evans At The Montreux Jazz Festival, Verve /Universal Music LLC, SHM-SACD (1968/2014)
    • Perfect, Live, Savitor/Damian Lipiński Pro-Audio Mastering (niepublikowana wersja remasteru), Master CD-R (1983/2017)
    • Richard Strauss, Also Sprach Zarathustra
    • Don Juan, dyr. Herbert von Karajan, wyk. Berliner Philharmoniker, Deutsche Gramophon/Polydor K.K. POCG-9357, „Karajan Gold”, Gold-CD (1984/1993)
    • The Danish Radio Jazz Group, Krakow Jazzklub, Poland 1966, Jazzhus Disk JD-7631, CD (2012)
    • The Oscar Peterson Trio, Night Train, Verve Records 521 440-2, „Verve Master Edition”, CD (1963/1997)
    • The Oscar Peterson Trio, Night Train, Verve Records/Universal Music K.K.Uccu-9430, SHM-CD (1963/2007)
    • Varius Manx, The Beginning, Polskie Nagrania „Muza”/Metal Mind Productions MMP CD 0425, CD (1992/2006)
    • Varius Manx, The Beginning, Polskie Nagrania „Muza”/SPV Poland SPV 00232, CD (1992/1994)
    • Vladimir Horowitz, Horowitz at the Met, RCA Red Seal/BMG Classics 633142, „High Performance”, CD (1982/1990);

    The hands I threw up at first now I had to use to applaud this amp. OK, that's not accurate, I didn't feel like applauding but rather like celebrating with some nice drink, but it reflects well the change in my attitude towards this amp that happened between Wiktor's arrival and the end of this review. This small, low-power device delivered an effortless, beautiful performance, a large scale sound and an amazingly low bass - and it was able to do it paired with loudspeakers that are not so easy to drive.

    I am sure that you've heard many times the catch phrase that "only the first watt counts." Like most such sayings, also this one incites suspicions. You can't really believe any such “statements”, as everything is subject to interpretation. In this case the point is, that the first watt counts wherever it has a chance to do the job. Which means, above all, in systems with high efficiency speakers. But let me tell you something else - the first watt counts in any system, with an amplifier of any output, provided that it is a "high quality watt", so to speak.

    In this context and in my understanding of this saying, the first watt symbolizes the resolution, clarity, dynamics and tonal richness, which is applicable in case of my Soulution 710 power amplifier (120 W / 8 Ω, 240 W / 4 Ω), 480 W / 2 Ω, current efficiency: 60 A), in the Leben CS600X (32 W / EL34) integrated amplifier, as well as when it comes to the tested Haiku-Audio SEinsei integrated amplifier (9 W). And the bigger output (more watts) has some advantages but also some disadvantages, as everything else in life, but they are only something extra, a bonus that comes at some cost (as does lack of it). When it comes to lesser quality amplifier, also the "first watt" is of lesser importance.

    In the case of the reviewed device, the first watt plays a key role. It just happens that it is one of the coolest 300B amplifiers I know. Maybe I'm not an expert on this type of device, but I've heard dozens of top products like that, some were just phenomenal, and I have healthy distance to the topic. And such devices as the Victor's amplifier, awaken the best part of myself. They are a combination of technical knowledge and musical sense. They are simply very good.

    Haiku-Audio plays “pastel” sound. It is not pushing forward as the costing a little more, Accuphase and Luxman amplifiers do, it's about a different modeling of the sound. This is about something inexpressible, which means that even though at first glance, there is not much emotion in it - these in a sense are "instilled" in listeners by the aforementioned amplifiers, and I would also add Leben CS300X to the bunch - but one still is excited about the music.

    I think that this is due to the aforementioned vivid three dimensionality of the presentation, i.e. the natural, very organic drawing of the panorama in front of the listener, as well as the low, strong bass and thus the foundation of the sound being placed quite low, a bit like with the Kondo OnGaku. The Polish amplifier has neither the resolution nor momentum of the Japanese masterpiece, but when it comes to the massiveness and volume of the presentation, it offers a similar approach. It is surprising, because the combination of nine watts with the Harbeths rarely works. And yet, in this case, it works.

    Impressed by how capable the amplifier turned out to be, I listened with it to a few discs in which the bass lines translate directly into their artistic expression and none of them disappointed, whether it was Richard Strauss and Also Sprach Zarathustra, or an instrumental debut of the Varius Manx The Beginning. It was a powerful, deep sound without any artificial emphasis in lower regions or underlining the upper bass, or hardening its attack. The sound was actually always and in every recording rather soft but with an intentional, not forced softness.

    I say "actually", because we have to remember of the 9 watts output which can't break lows of physics, it can only be skilfully used. In this case, it relies on the amplifier's very smooth transition input the overdrive state. Various amplifiers cope with this in a various ways, and tube designs soften or harden the sound, depending on the design (most often it depends on the feedback method).

    The SEnsei played all the time offering similar level of performance, without changing the consistency of the sound or its color. When pushed to its limits SEnsei signals it only with a slightly simplified macro-dynamics. But you have to know what to look for to realize it. In "blind listening" it will be very difficult. With high efficiency speakers it probably will not come out to that, but even with the Harbeths it was not in any way annoying, let alone disqualifying.

    One of the next things that drew my attention was the way of presenting space, or imaging. It's an amplifier that presents or develops events behind speakers. When needed, it accurately reflects the out of phase layers, but always in connection with the "base" that is placed behind the line connecting the speakers. It builds everything far into the depth of the stage, but - this is the second feature - the most important are the foregrounds. As a result, we receive an involving, intense presentation, but at the same time it is slightly distanced, the sound comes to us with a slight "delay", already fully formed and arranged.

    And I think that's what I wanted to get to, the gravity pushed me in this direction, to a brief statement: it is a very nice, pleasant and - yes - well-arranged sound. It has something of nonchalance of a successful man to it, one who doesn't have to do anything, but is able to do almost everything. It plays in a soft way, with a truthful softness, and not pretend one, one that lets you experience the music in a deep, meaningful way.

    And yet, it is extremely resolving, because it very well emphasized the differences between the various editions of The Oscar Peterson Trio's Night Train ("Verve Master Edition" and SHM-CD), and the already mentioned Varius Manx's album. At the same time, the SEnsei added to them its own sonic "feature", making them slightly more three-dimensional and making the listening experience more enjoyable. Even The Danish Radio Jazz Group, recorded in an unknown Krakow club in 1966, on a rather primitive, mono tape recorder, sounded nicely and pleasantly with this amp.


    The SEnsei 300B SE is a versatile amplifier that can work well with a wide range of loudspeakers, not necessarily high-efficiency ones. Which gives it an advantage over other low power SET amplifiers, because it allows you to choose the loudspeakers you want, not ones we have to choose because of their specifications. Over time, you will realize that it offers not only a pleasant sound, but also an intrinsically complex, multidimensional, resolving and palpable. At some point you will stop listening to it for the sound and start listening to the music. With a strong low bass, great control over the speakers and a relaxing but tangible panorama. RED Fingerprint! ■

    Technical specification (according to manufacturer)

    Output: 9 W
    Operation: Class A SE
    Tubes: 2xECC81, 2x300B, 1xGZ34
    Front: black or silver

    Frequency range:
    -1 dB: 14 Hz–35 kHz
    -3 dB: 7 Hz–51 kHz
    Power consumption: 250 W
    Dimensions: 450 x 380 x 190 cm
    Weight: 20 kg


    Reference system 2018

    1) Loudspeakers: HARBETH M40.1 |REVIEW|
    2) Line preamplifier: AYON AUDIO Spheris III Linestage |REVIEW|
    3) Super Audio CD Player: AYON AUDIO CD-35 HF Edition No. 01/50 |REVIEW|
    4) Stands (loudspeakers): ACOUSTIC REVIVE (custom) |ABOUT|
    5) Power amplifier: SOULUTION 710
    6) Loudspeaker filter: SPEC REAL-SOUND PROCESSOR RSP-AZ9EX (prototype) |REVIEW|
    7) Hi-Fi rack: FINITE ELEMENTE Pagode Edition |ABOUT|


    Analog interconnect SACD Player - Line preamplifier: SILTECH Triple Crown (1 m) |ABOUT|
    Analog interconnect Line preamplifier - Power amplifier: ACOUSTIC REVIVE RCA-1.0 Absolute-FM (1 m) |REVIEW|
    Speaker cable: SILTECH Triple Crown (2.5 m) |ABOUT|

    AC Power

    Power cable | Mains Power Distribution Block - SACD Player: SILTECH Triple Crown
    Power (2 m) |ARTICLE|
    Power cable | Mains Power Distribution Block - Line preamplifier - ACOUSTIC REVIVE
    Power Reference Triple-C (2 m) |REVIEW|
    Power cable | Mains Power Distribution Block - Power amplifier - ACROLINK Mexcel 7N-PC9500 |ARTICLE|
    Power cable | Power Receptacle - Mains Power Distribution Block: ACROLINK Mexcel 7N-PC9500 (2 m) |ARTICLE|
    Power Receptacle: Acoustic Revive RTP-4eu ULTIMATE |REVIEW|
    Anti-vibration platform under Acoustic Revive RTP-4eu ULTIMATE: Asura QUALITY RECOVERY SYSTEM Level 1 |REVIEW|
    Power Supply Conditioner: Acoustic Revive RPC-1 |REVIEW|
    Power Supply Conditioner: Acoustic Revive RAS-14 Triple-C |REVIEW|
    Passive filter EMI/RFI: VERICTUM Block |REVIEW|


    Speaker stands: ACOUSTIC REVIVE (custom)
    Hi-Fi rack: FINITE ELEMENTE Pagode Edition |ABOUT|
    Anti-vibration platforms: ACOUSTIC REVIVE RAF-48H |ARTICLE|

    • HARMONIX TU-666M "BeauTone" MILLION MAESTRO 20th Anniversary Edition |REVIEW|


    Phono preamplifier: Phono cartridges: Tonearm (12"): Reed 3P |REVIEW|

    Clamp: PATHE WINGS Titanium PW-Ti 770 | Limited Edition

    Record mats:


    Headphone amplifier: AYON AUDIO HA-3 |REVIEW|

    Headphones: Headphone Cables: Forza AudioWorks NOIR HYBRID HPC