aunching a few new products in a short period of time requires a lot of effort from a specialist audio company. For a small firm, such as Haiku-Audio from Cracow, it is like being turbocharged with jet fuel. And we only just tested its largest integrated amplifier (so far)– the iovita in June. However, circumstances are clearly favorable for the company’s development and there are people willing to get acquainted with different types of Haiku-Audio products.

The SOL III differs from all Wiktor Krzak’s (the owner of Haiku-Audio) products that we have already presented in “High Fidelity”. It is a 100% solid state amplifier (SOL = SOLid State), whereas the ones that we had tested before were hybrid amplifiers with a tube preamplifier and a transistor power amplifier. It is already the third version of the SOL model that is described on the company website in the following way:

The simplicity and transparency of the circuit, as well as the way the SOL amplifier reproduces sound make it more similar to tube amps than to traditional transistor designs. The heart of the circuit is one Single-Ended transistor stage. A push-pull pair of A-class transistors is located on the amplifier output in order to increase output power and make it possible for the amplifier to work with speaker sets with a complicated impedance course. The whole amplifier has three gain stages and is not placed in a feedback loop.

A stronger version of the SOL – the SOL II model – was created after some time. It had double power, up to 50 W/8 Ω and 90 W/4 Ω, and many improvements were introduced in the circuit. For example, the amplifier was equipped with a stabilization circuit and additional enormous capacitors (total capacity: 0.1 F). Volume was controlled using a DACT switch potentiometer with gold-plated contacts and channel synchronization better than 0.05 dB already from the first step.

The SOL III was created on that basis. At the time of the test there is still no information about it on the company website but it is known that there has been a significant increase in the price – from 8700 PLN for version II to 14,400 PLN for version III. Why is it so? The reason for the higher price are, of course, changes introduced in the design. I asked the constructor himself about them and their purpose.

WIKTOR KRZAK
Owner, constructor

The SOL series includes transistor amplifiers consisting of three gain stages – not many, compared with transistor standards. When it comes to topology, they are more like tube amplifiers than average transistors, all the more that the main point of the amplifier is the middle Single-Ended A-class control stage. Moreover, the circuit has no global feedback.

The latest SOL III version is different from the previous ones when it comes to its dual-mono circuit, i.e. separate power transformers for each channel, its housing made entirely of anodized aluminum and processor which controls the on/off procedure, input selector and remote control. The input selector itself is placed on a gold-plated plate and uses air-tight signal transmitters. The best quality components are used in the amp, including Nichicon-Gold capacitors, precise metalized resistors in the whole circuit or Toshiba transistors. The power transformers are manufactured by Haiku-Audio. These are rarely used toroidal transformers with a tall core and excellent parameters.

Output power has been increased to 60 W/8 Ω or 110 W/4 Ω (constant power). During measurements it was possible to obtain 90 W/8 Ω and 145 W/4 Ω of instantaneous power, respectively. Idle power consumption of the device is 100 W and peak power consumption is almost 0.5 kW.

All amplifiers from the SOL series are produced in two versions: an integrated amplifier and a power amplifier. The integrated amplifier has a pre-out socket which can be used to connect an additional power amplifier in order to get a bi-amping set without the need to have a separate preamplifier. A black and a silver version are available. The price of the amp is 14,400 PLN (the integrated amplifier) and 12,000 PLN (the power amplifier).

SOL III looks very similar to the iovita and to the Haiku-Audio Bright Mk3. As regards the height of the devices, the iovita is higher than the SOL III and the Haiku Bright Mk3 is lower. All amplifiers manufactured by Mr. Krzak have a similar housing based on modules produced by the Italian company Modu, also used by other firms that our readers have got acquainted with thanks to “High Fidelity” – sinusAudio (review in Polish) and RT Audio Design.

These are robust and aesthetic housings with characteristic radiators on the sides. The front has been designed by Haiku-Audio and it is almost identical for all the company’s amplifier models. It is an aluminum plate with an opening to place a black insert on which there are input switches with green rims, a button which reduces signal by 20 dB and the standby switch (both with orange rims). Next to them there is also a large robust volume control knob that is very characteristic for this manufacturer. Such an arrangement of elements is included in the company logo, which looks really professional and aesthetic. The only problem (if it is a problem at all) is the fact that all the company’s amplifiers look very similar at first sight.

The SOL III is an integrated amplifier with high output power, to which we can connect an additional power amplifier. This is what the unbalanced amplifier outputs controlled by a potentiometer are for. And where is the beautiful “DACT switch potentiometer with gold-plated contacts and channel synchronization better than 0.05 dB already from the first step”? Well – the deity of progress demands sacrifice. Having been pressed, pushed and molested, Wiktor finally gave in and decided to control volume remotely – both in the iovita and now in the SOL III. Everything has pros and cons, right? Functionality and user comfort have been improved in this way, but we get a slightly worse attenuator (mainly when it comes to channel balance, but not only).

The remote control is minimalist and very easy to use. The high plastic column has a standby switch, volume control and a button which reduces signal by 20 dB. There is no classic “mute” circuit here.

Interconnects

Haiku-Audio has only recently started manufacturing and selling interconnects. We got the tested amplifier with interconnects that we comment on in a separate section of “The listening session” in this article. The cables look quite ordinary, they are very thin and have no fancy decorative mesh on them. The really nice element are their pins produced by the American Charming Music Conductor (CMC) company. The semiconductor is a thin cord made of silver-plated copper. The uniqueness of the cables lies in their geometry and the materials that the dielectric is made of.

The inner insulation in Haiku-Audio interconnects is made of an electret, i.e. material which maintains a constant electric field. It can be compared to an electric equivalent of a permanent magnet. Using such insulation has an effect similar to when an external amplifier is used, but without any complications or discomfort for the user.

Another untypical feature of the cables is the arrangement of the signal conductor. It is loose and comes into contact with the dielectric at a few points only. As a result, most of the conductor has air insulation which is characterized by excellent linearity. Additionally, the capacity of the cable is reduced, making it more friendly for delicate sources, e.g. ones that have tube outputs.

The outer glossy black insulation is a non-flammable polymer which has unique mechanical properties. It makes the cable a bit rigid but virtually impossible to damage, at the same time effectively preventing Haiku-Audio cables from getting tangled. The price of the interconnects is 590 PLN for 75 cm.

The stereotypical opinion that tubes provide warmth and transistors give power, and therefore hybrid amplifiers are a perfect combination of these two features, is both true and false at the same time – just like any other stereotype. It is true from a historical perspective because people really used to try to “tune” these amps in this way. A good example of nice devices of this type were Jolida amplifiers.

However, it is also false, because what is discussed here are choices, not real pros and cons. Hybrid amplifiers (and more broadly: devices) have not sounded like this for a long time. It is because good tubes do not give us “warmth”, but rather an abundance of colors and great linearity, while transistors do not really give power but build a robust sound structure, giving it both tube and transistor features – such as high dynamics and low noise, etc. Good examples of top-class modern hybrid amplifiers are: the Trilogy 925 and the Linear Audio Research IA-120H.

I have recalled the stereotype of a “warm and powerful” hybrid amplifier for a simple reason: the hybrid iovita amplifier that we tested a few months ago did not have anything in common with it. If we put the iovita and the tested SOL III next to each other and told test participants that one of them has a tube preamp and the other one a transistor one, and that both are solid-state power amps, I am sure that most people would say that the SOL III is a hybrid amplifier – not because it sounds warm, but because it is closer to the stereotypical representation of this type of a device than the iovita.

The new Haiku-Audio amplifier sounds fresh and loud. The loudness relies on the high energy that the device transfers to the room and the presence of huge sound images, high volume and an excellent definition of instruments. The freshness refers to open sound without rounding the attack of the treble, characterized by amazing resonance. It is not stereotypical “tube” sound, as it does not warm up, smoothen or additionally sweeten anything. It is the kind of tube sound that really improves sound and not only “kind of makes it” nice and safe.

I think it is because the clarity and dynamics. Both these features are very prominent in the SOL III. Therefore, sound sources have solid 3D images and are large. Their foreground is located a little behind the line which connects the speakers and they rarely “step out” in front of it – unless the sound engineer decided to tune up the vocal, e.g. on Nat ‘King’ Cole’s albums. I think that such a perspective comes from the musical training that Wiktor has received – in classical music it is always about showing an event from a certain perspective, emulating a situation that took place at a concert hall. The SOL III does not move everything to the background to such an extent – all in all, it is a reproduction of material recorded using microphones, i.e. “made-up” already at the recording stage. However, the Haiku-Audio amplifier does not bring anything forward, either.

Listening to the device was extremely pleasant and comfortable for me. I was able to appreciate the well thought-out tonal balance, stability of instruments on the stage and great differentiation. The last of the features makes us listen to music with interest, which is not easy when we listen to our favorite or “test” material the n-th time. This time there was no problem with that and I flowed with the music, taking out one album after another, in accordance with what my curiosity and imagination prompted me to choose, without paying attention to the selected “set”.

As regards the tone, the SOL III sounds fresh but also a bit saturated. Vocals sound open, with clearly articulated sibilants which neither dominate nor are emphasized and are, therefore, clearly heard. We get good selectivity but do not reach a point where it would dominate in any way. This is a feature which makes us look closer at the speakers that are going to be used with the amplifier.

This is because the tweeter and the corresponding section of the crossover are usually at the bottom of our list of expenses, because of which they emphasize the attack, are not sensitive to sound shades and only select those sound elements that can be “roughly” heard. If we connect this with an amplifier which does not round sound up, sibilants may get over-interpreted, leading to the brightening of sound. If we hear something like this with the SOL III, let us remember it means there is a problem with the speakers, not with the amplifier.

Anyway, we may not notice that at all because the device excellently saturates the bass, shows its power, textures and colors. After listening to it for a longer time, it is possible to feel a slight increase in the lower midrange, because of which the sound is never too light, even if the given album goes in this direction. High power makes it possible to control the dynamics of the lowest range freely. The sound structure is preserved even in such demanding recordings as Falling from Laurie Anderson’s Homeland album, with accurate bass control and its beautiful saturation.

The sound stage, or rather imaging, is another strength of the SOL III. The amplifier shows space in a way which does not attract attention. Instruments have their own space around them and constitute part of the same “universe”, while the elements around us (if there are any) have nice timbre and are precisely located.

Interconnects

I think that interconnects offered by Haiku-Audio were listened to at the production stage in combination with the company’s amplifiers, which is probably obvious and can be heard straight away. They add some warmth and a stronger bass to the sound, as well as slightly correct the attack of the treble. When compared to more expensive reference cables, they show this means interfering with sound, but in order to achieve a specific effect – probably to increase the volume and add “color” to the system.

This is sound in which dynamics and energy come first, and the attack is slightly rounded. The low range is controlled really well, but it is not a case in which we get clear textures and definitions. It is similar with the treble which is otherwise active and precise. The cables really well reflect spatial depth, without cutting off background elements or gluing them together.

These are nice good cables characterized by high dynamics and nice bass – perhaps without especially good resolution, but that is the domain of expensive interconnects.

Summary

People who value coherence, dynamics and truth in music will like the SOL III. Its sound is accurate, dynamic and sonorous, as well as nicely saturated and colorful. It neither hides anything, nor focuses on the disadvantages of recordings. The slightly increased low midrange is a good thing to have in this case, as it gives recordings swing and depth.

The amplifier is really well-made, although its functionality is limited – there is no recording output (to which we could connect a headphone amplifier) or DAC, it is not possible to send Bluetooth signal, as well as there is no phonostage or headphone amplifier. Most amplifiers manufactured by large companies, from the price range of up to 15,000 PLN, have all these elements.

However, this is what a purist amplifier from a micro-manufacture looks like. Its defends itself with its really exquisite sound and the feeling that there is a real person with an idea behind it.

Haiku-Audio is a small company led by an audio enthusiast, active musician and, generally speaking, a “positively twisted” man focused on his passions. However, Wiktor Krzak is not only a “God’s madman”, but also a competent manager who can count money. Without that, no company (no matter how brilliant its products are) has a chance to survive.

The SOL III, just like all other Haiku-Audio products, is a purist minimalist device with excellent components and a refined (though simple) design. The elements of the housing are standardized in order not to unnecessarily increase the prices. Therefore, the SOL III resembles other Haiku-Audio devices from the outside. Its rigid housing is made of aluminum elements – panels and radiators. There is a double bottom panel – it has been reinforced to allow the amplifier to be attached to a stable basis. The upper panel that is attached to radiators has been damped using a piece of material manufactured by General Music System – it is a layer of aluminum and a vibration-damping material.

The front and back

In my opinion, the front panel is really nice, as it is minimalist and clean at the same time. There is an oblong opening in its surface, with a piece of black acrylic attached at the back. One can see the lights of button rims – a green one indicating the chosen line input and two orange ones (signal reduction by -20 dB or the standby switch). The mechanical switch which cuts off power supply is integrated with an IEC power supply socket. On the right there is a huge black aluminum volume control knob.

There are four line inputs in the device, in the form of nice, gold-plated RCA sockets. It is worth paying attention to their configuration – their pairs are placed vertically, separated by quite a large distance. One can notice that their colors are different from what is commonly accepted – red and green. What is more, the channels are labeled in a different way, as the color red is assigned to the left channel, even though in engineering it is used to label the right channel.

As I wrote in the introduction, an additional power amplifier can be connected to the amp and speakers can be controlled in the bi-amping system in which one power amp supplies the tweeter sections of both channels and the other one – the woofer sections. Of course, it is necessary to have double clamps in speakers for this purpose, from which we remove the metal plates that fasten them (jumpers). The device also has single gold-plated speaker outputs that are convenient to use.

The inside

The SOL III has a dual mono design, with separate power supply units, and left and right channel amplifier plates attached to the radiators on both sides of the housing. The only elements that they have in common are: the board with inputs and relays, and a blue Alps potentiometer with a motor.

When we look inside, our attention is mainly attracted by the powerful power supply unit with large toroidal transformers. They are tall and do not have a large diameter – Wiktor has already mentioned that. Each transformer is accompanied by an enormous capacitor, with a diameter similar to the diameter of a Coca-Cola can of 250 ml capacity. Next to these elements there are also integrated bridge rectifiers attached – for cooling – to the bottom panel of the housing.

The amplifiers are mounted on single printed circuit boards – it is a circuit with an attenuator on the input. It only has three stages, of which the middle one operates in class A, in a single-ended circuit which resembles a tube circuit. Nice passive components are used here, e.g. precise resistors and Wima polypropylene capacitors. There are also orange LEDs, visible through openings in the top panel, operating as voltage references. The whole circuit looks quite simple and that is the point – to make it simple, but not primitive.

The remote control

The remote control is a universal control device with the RC-5 code. It is made of plastic and surprisingly convenient to use. It has a large “standby” button, two volume control buttons, two more input change buttons and a small “mute” button reducing volume by 20 dB. Reducing signal by 20 dB means a big change from playing loud music to playing background music. This function can be useful during a telephone call or in situations when we want to hear what our “second half” is trying to tell us. I am sure that most of our partners would like to possess such a button forever :)

Technical specifications (according to the manufacturer):

Output power (8 Ω): 90 W
Output power (4 Ω): 140 W
Frequency response (-1 dB): 14 Hz-52 kHz
Frequency response (-3 dB): 8 Hz-84 kHz
Operational class: A/AB
Input sensitivity: 600 mV
Idle power consumption: 100 W
Power consumption (max): 500 W
Dimensions: 450 x 360 x 190 mm
Weight: 20 kg
Previous panel versions: black or silver