Made in heaven

"...the amplifiers do not only "disappear" the cabins but also the baffles with the loudspeakers, resulting in a perfectly open window with... infinite depth."


  • Two stage hybrids
  • 1x210Wrms/8Ω
  • Touch bar

hARt Lab Superior Monoblock Tune Five

Made in heaven



hARt Lab was "born" in 2017 and in 2019 made its debut at the Munich Exhibition, with a static demonstration of the Tune One integrated amplifier with EL34 tubes and the Reference Tune Two preamplifier with CV181 tubes. The years of lockdown did not go unexploited for this new premium Greek company and at the 2022 Exhibition it returned with its full range (except the integrated amplifier), which consists of the pre-power set of the Reference series, Tune Two and Tune Three and the Superior series pre-power monoblock set, Tune four and Tune Five. The latter costs close to a hundred thousand for these three chassis (no external power supplies), which have excellent build quality and provide full functionality on the preamp side.

Before you get... indignant about the company's prices, it's good to ask yourself if an absolutely top product like this can cost less, when it's actually not made in China but in Euro Greece. A product, in fact, so special that it could blow up the unwritten rules of the ultra high-end scene. For our part, we are sure that hARt Labs - when they hopefully reach foreign markets - we will see them cost significantly more in order not to disturb the balance of this special market, since their performance corresponds to six-digit retail figures. The good news for those who are really interested in the sound of the company and feel proud of its origin, is that it will not be long before two integrated amplifiers are presented with a price close to twenty thousand each, the Tune One with EL34 tubes but also a hybrid with trickle down technology from the Superior set.

But what great thing did the people of hARt Lab discover, which led them to found a company and enter the suffering of the production of made in Greece? A circuit, what else! A circuit developed by designer Kostas Trovas for 25 years, whose experience includes servicing and upgrading almost every high-end gear produced in the last three decades on the planet. This does not automatically make him a genius, but it has given him the ability to evaluate and rank almost every circuit and electronic element in the high-end market. And based on these data, to submit his own opinion on the ultimate reproduction. Of course, such a designer - judging by the result - can only have the gift, the appropriate "cultivated" senses and the ability to process them to achieve his goal. Mr. Trovas followed in the footsteps of the hybrid power amplifier circuit, but managed to keep it extremely simple with only two amplifier stages for the Tune Five.

One tubed for the voltage gain with CV181 tubes and one with transimpedance topology mosfet for the high-power output current. In addition, the circuit is devoid of any feedback loop, either local or global, so in the laboratory the gear does not aim for the lowest possible distortions, starting with about 0.5% THD at 1W and giving the power of 210Wrms with just over 5% distortion. Harmonic distortion is however "tubed" with even harmonics dominating and the output impedance is not as low as competing high power products, resulting in a damping factor of close to 35 for 8Ω loads. In other words, Tune Five measures very well but not perfectly. However, in addition to the circuit, which is the simplest we have encountered in a hybrid, the Tune Five works with the absolute "tuning" of the materials down to the smallest detail and this allows for a shocking homogeneity and purity in the hybrid design, where the many years of experience of the designer become apparent.

But a designer alone can't do much, he might as well make a few pieces for himself and his friends but that's about it. On the contrary, hARt Lab is a tight-knit group of three Greeks linked by many years of friendship, with Mr. Nondas Gaveras in charge of the commercial part and the design of the appearance and perceived quality of the amplifiers and the "chief engineer", electronic Mr. Nikos Fanakis to be responsible for the final assembly, quality control and development of the digital facilities in the preamps and integrated. Mr. Gaveras has admittedly done a great job on the visual side, with the Tune Five looking gorgeous and relatively compact despite the despite their 30kg weight. He has succeeded in vividly portraying their unique sonic behavior but, as much as he has excelled, the beauty of the monoblocks' sound is even better than their appearance! Let's see them up close.



The striking white surfaces reflect the inner sonic purity on the tall front of the Tune Five, contrasting sharply with the large illuminated logo. The metal "touch bar" below it is a touch button for starting, stand by and choosing the colors of the lighting. The facade is not aluminum but wooden and it is not even a pure facade but it also has... a "cover" as it extends to a depth of 7 centimeters. The same pattern on the back, except that there the panel is acrylic and the depth of the wood-frame reaches 12 cm. So, the chassis looks like a wooden sandwich in the middle of which is a sophisticated metal structure, with the bases of the transformers, the heatsinks, the back, the hidden front and the removable metal lid, which has grills like the heatsinks. The woods are painted with the MlCoat process with multiple layers, leaving a sense of perfection to the eye and hand. Some will notice that the gaps between the front and side panels are not perfect. This is because the latter are attached with elastic links with little room for movement (we straighten them easily) and are removed by the user by hand (slide down,) to change the look/color if desired, which is fashionable today.

Also cool is the color code of the lighting in the logo that changes three colors on startup, flashing first red and then green to show the warm-up, and when it's done, it ends up solid in the color of our choice. By simply pressing a small button on the back of the terminals (top right, in a convenient place) we activate the "menu" and by successively touching the bar we "run" the color palette of the 15 available colors, leaving the one we want for the operating mode. With a second press we can, again through the bar, adjust the brightness to three levels or turn it off completely. This is where the user interface ends, after all we are talking about power amplifiers without XLR input (since the first stage is singleended) so there is no switch on their back. But there are two outputs for speakers with Cardas plugs (no choice) and trigger terminals for starting through the company's preamplifier, which will be controlled with an app for remote starts of the set so that it is waiting for us warm for listening.

Inside, minimalism and fine materials dominate. The tube stage includes the TiPD circuit with two parallel CV181 (corresponding to the 6SN7GT-here Psvane with carbon on the glass and Teflon on the base), where we find Miflex KPCU-01 oil coupling capacitors (paper-polypropylene-solid copper foil) and the solid state relies on four Exicon mosfets per side/heatsink. The power supply of each monoblock includes two custom toroidal transformers (upright, back-to-back), four Nippon Chemicon 47,000μF electrolytic capacitors and is based on the VAcc battery emulation technique. It should be noted that the Tune Fives are not from a typical Tune Three solid-state conversion as they do have a higher supply voltage and parallel/double power supplies, tubes and heatsinks, but they are designed for maximum linearity, have a different board architecture and just perform a bit more power, with 210W against 165W. That is, we cannot take a Three and turn it into a Five at a later time.

The chassis has a special architecture to combine stiffness and low energy storage, and support is provided by custom FloatO legs that act as a suspension with light floats in both the horizontal and vertical planes, as if the chassis is floating. Overall, the Tune Five harmoniously combine wood, metal, plastic and rubber and CNC and 3D printing manufacturing methods to implement their unique circuit without losses and at the same time leave a contemporary sense of luxury with the sole purpose of being eye catching and the ear grabbing. Having had enough of the first, let us now move on to the second.



For the comprehensive evaluation of Tune Five, hARt Lab "lent" us its small Tune Two preamplifier, which was connected from its direct output to the monoblocks, which is exclusively tubed (one CV181/channel) as there is also the hybrid with lower output resistance. This was done both to get a better picture of the company's sound and because of the low sensitivity of the amps that require several volts at their inputs and therefore preamplification with a sufficient voltage gain.

Our familiar sources (Lyra Delos /Thorens TD160 /iFi Phono 3 BL and Pioneer UDP-LX800) were connected to Tune Two and the power amps drove the ATC SCM70SL and Paradigm Founder 40B. The first impression is that of a perfectly neutral tone curve and balanced stage presence, almost as if playing a top-of-therange bipolar transistor amplifier, where speed in transients and transparency are the "expected", without thicknesses, roundings and embellishments or projections. But it soon becomes apparent that there is no "grey fog" from the low-level signals, no emphasis on contours, and no unnecessary brilliance from the transients. It also becomes apparent that the timbre density, while top-notch, contains no trace of unnatural "condensation" of timbres as most tube amps do due to intermodulation, effectively degrading elements of timing, contrasts and flow.

Finally, and although the Tune Five do not "address us personally" in the direct way that the single-ended ones direct their sounds at us (see Grandinote Shinai), nevertheless all their sounds have a clear directionality (in all possible directions of the stage) and they do not move stereotypically on the vertical axis like most push-pull but in... 3D mode, with legendary agility for the idols around their unshakable positions on the stage. And at the "zero" level, as defined by the acoustic centers of the loudspeakers, there is no crowding, slowing down, enlargement or discontinuity (like bottleneck congestion) and the amplifiers do not only "disappear" the cabins but also the baffles with the loudspeakers, resulting in a perfectly open window with... infinite depth.

At this point some might say that the Tune Five are a little "gentle" dynamically, but in reality, they don't hold back the energy so everything comes out crisp, light and airy. Sonographically, we hear the 6SN7GT in high spirits, with a terrifically organic and bright timbre, a feast of color and award-winning hologram, fantastic resolution and extension in the bass and treble, but superbly controlled tonally so that it doesn't drift off to do its own thing. The same can be said for the mosfet output stage, it has tremendous power across the spectrum with incredibly deep and powerful low end and a truly rich tone, yet makes no compromises on speed, crystal focus and space around instruments while it never gets dark. A sound-utopia that we did not expect to hear!

The Tune Fives, after all, don't sound hybrid, tubed or solid state in the sense of "signature" in harmonics, velocities, temperatures and textures. They touch with their naturalness the realism of the sounds that surround us and capture the musical message in the mind and heart with the immediacy of live music. Our ATC has never achieved such a performance until now - it "danced" freely and happily to the beat of the music, with the densest and deepest lows and the most colorful and clear mids and trebles we've heard from it - while even the small Paradigm blew us away with his heavenly timbres and incredibly emotional interpretation of recordings, we thought we had "got" until today.

Tune Five have no "me" and "look at me playing now" at all, they take the art of high fidelity to the most humble and unfathomable heights we've ever heard, which is why they're worth every last euro they're asking for.



A "hybrid" of high class and extreme circuit simplicity, which ideally "marries" tubes with a powerful mosfet stage. With a beautiful appearance and luxurious construction, the hARt Lab monoblocks are very expensive, but they reward us with the maximum possible purity of sound colors and the "lightest" absolute driving of the most difficult speakers.

TYPE: Monoblock hybrid power amplifier
POWER: 1x210Wrms@8Ω/1x350Wrms@4Ω
INPUT: RCA (3.4Vrms)
DIMENSIONS (WxDxH): 430x410x200 mm.
CONSUMPTION: 190W at idle
WEIGHT: 32 kg



CONTACT: tel. 210.6833600
RATING:  (4.99/5) high end
PRICE: €32,600 each

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