Accustic Arts Mono II power amplifiers and Tube Preamp II MK2 test and review


I’ve stumbled upon the Accustic Arts components through Walter Kircher, their sales agent. We’ve exchanged quite some emails and messages that eventually led to the first Mono & Stereo and Accustic Arts special listening event.

The complete Accustic Arts system grabbed my attention and eventually I got an opportunity to experience in-depth their MONO II power amplifiers, Tube Preamp IIMK2 and Tube DAC II. 

In this test and review I’ll be focusing on the MONO II power amplifiers and the Tube Preamp II in trying to bring the best insights.

I’ve had a pleasure to hear both the MONO II power amplifiers and the Tube Preamp II in my own reference setup as well as with the state of the art SoulSonic flagship Impulse speakers. This combination brought out the best of Mono II power amplifiers and Tube Preamp II and I will mostly focus on this dedicated combination as it represents a state of the art system that is capable of really impressive reproduction in the EUR 200.000 region of systems pricing scheme.

Let us first take a look into the technical side of both units.

MONO II highlights (per monoblock):


Reference class mono power amplifier
12 selected MOS-FET output transistors of finest quality
Magnetically shielded and encapsulated toroidal core transformer of premium quality for highest output reserves
Maximum total transformer power: 1200 VA (watts)
Optimum smoothing thanks to more than 80,000 µF power supply capacity; Premium quality capacitors (“Made in Germany”)
Very high damping factor for perfect speaker control
Professional protective circuit against clipping, HF oscillations and too high DC offset
Constant low operating temperature due to generously dimensioned heat sinks
Balanced input (XLR) and unbalanced input (RCA) – the inputs are switchable on the rear panel
All used parts and components are selected and of highest quality
Premium quality, gold-plated bi-wiring / bi-amping speaker terminals
Mains power switch on the front panel
Extremely stable and resonance optimized, massive aluminium housing; inlay made of massive, high gloss polished and chromed brass
ACCUSTIC ARTS® MONO II is “Handmade in Germany”

ACCUSTIC ARTS® MONO II power amplifier is the first MONO output amplifier from ACCUSTIC ARTS and the latest addition to the ACCUSTIC ARTS® family of power amplifiers. MONOII DNA is based on the company already established AMPII, which already found many happy homes around the world.

ACCUSTIC ARTS MONOII continues the company “leitmotiv” design in timeless Bauhaus shape that clearly radiates a special aura which can stand the test of time and can actually aesthetically please and carry on with all generations.

From the ground up MONOII is designed as an optimized high-performance power amplifier. ACCUSTIC ARTS technical team strictly focused on the short distances in the circuits and with the selection of finest components. As a rule in the upper echelon of power amplifiers every electronic part is strictly selected and measured for maintaining the best tolerances. But this doesn`t stop at the technical level, namely, ACCUSTIC ARTS is one of the few companies that strongly advocates the listening fine tuning, along with an urge for technical perfection. MONOII feels like Made in Germany product from the first glance, but behaves beyond expected in sound performance. It transcends the way typical German high-end components sound (precision above emotion) and welcomes the radiant, emotional impact.

Before delving deeper, what makes MONO II exceptional performers? As already mentioned the first thing is surely the selectivity of the materials, next comes strong, potent power supply. Made in Germany, this strong toroidal transformer with 1200 VA rating, a special core and additional Mu metal shielding along with 12 hand selected MOSFET output transistors and 8 large power supply capacitors (10.000 µF) manufactured in Germany to ACCUSTIC ARTS` exact specifications, ensure the amp can deliver thunderous power with ease and without any struggle. This helps in presenting the music with natural flow and without dynamic constraints.

What does this mean in earthly language? Properly sized and refined power supply is something not too many high-end audio designers are paying enough attention to. Another thing is how gain stages work and how and where the signal is attenuated. Like with my reference Robert Koda Takumi K–10 preamplifier (27.500 EUR), at the highest operating level the electronic components are hardly pushed to the limits and they can keep the distortion levels down. This is an open secret that only few designers fully understand but it brings out the music reproduction on the reference level. DartZeel uses this in its own way but basically employs the similar principle.

The heart of ACCUSTIC ARTS MONOII is certainly its very high current capability coupled to a really fast and responsive power supply that gives an incredible control of all speakers and loads. I cannot stress enough the importance of a FAST and POWERFUL power supply for realistic music reproduction but this is obviously something Mr. Martin Schunk, the Accustic Arts electronic designer knows extremely well.

MONO II is also designed from the ground with enough room to keep the air flow and let the circuits ventilate at the best temperate point, without bringing the performance levels down.

ACCUSTIC ARTS PREAMP II MK2 HIGHLIGHTS


Audiophile reference preamplifier with a so called “tube hybrid” concept and 4 military tubes (2 tubes per channel)
Fully balanced circuit design from input to output
Advantages of this “tube hybrid” technology:
- very high impedance
- very high bandwidth
- very low distortion factors and a “good-natured” distortion spectrum
- “analog” and very precise sound performance
- 4 separated amplification paths, which are not influencing each other
Easy change of tubes without any adjustments just “plug and play”
Professional Class A output stage using technology derived from studio engineering
All used components are of outstanding quality (e.g. Burr Brown® OPA 627) and additionally selected; all relays have high quality gold-plated contacts
4 high precision military tubes; 4-times selected
4-channel volume potentiometer for best crosstalk
3 x fully balanced high level inputs (XLR) and 2 x unbalanced high level inputs (RCA)
1 x unbalanced input (RCA) configured as “SURROUND-BYPASS”
2 x fully balanced outputs (XLR) – 1 x AC coupled, 1 x DC coupled
2 x unbalanced outputs (RCA) – 1 x AC coupled, 1 x DC coupled
1 x headphone output, switchable (1/4" stereo female jack)
1 x unregulated, switchable output for the connection of an external headphone amplifier (RCA)
Phase switch for 0° and 180°
2 magnetically shielded, encapsulated 75 VA toroidal core transformer (“Made in Germany”) of premium quality for high output reserves
Front panel, cover and remote control are made of massive and solid aluminium; turning knobs made of massive and chromed brass
ACCUSTIC ARTS® TUBE PREAMP II – MK 2 is “Handmade in Germany”

MADE IN GERMANY


ACCUSTIC ARTS are clearly proud of their Made In Germany signature. Both MONO II and TUBE PREAMP II are exclusively manufactured in ACCUSTIC ARTS premises in Lauffen am Neckar, Germany. As an important part the company states:


“The development, component insertion of PCBs and final assembly takes place in Germany and all housing parts and many individual components are sourced from long-term suppliers based in the south of Germany. Our specially trained and experienced technicians build this high-end audiophile amplifier from a large number of individual components.”

A sudden burst of life energy!


Although there may be differing opinions among audiophile crowd in regard to the order of importance of all components in the reproduction chain, the fact remains that amplifiers play the VITAL ROLE in all systems that are aiming for the ultimate in sound quality levels. Like with every component there are technical requirements and of course, sonic requirements. With amps, the technical requirements address the target electrical power levels and things like stability, dynamic headroom, etc.


If we agree that the sound of live, un-amplified instruments and voices contains the highest levels of dynamics (dynamic swings) that at the present our high-end audio systems can only approach to some point, but never fully reach, then we are starting to realize the immense challenges each high end audio amplifier designer is confronted with.


Electrical power (static power) is one thing and dynamic responsiveness (dynamic power) is another, but of course, they are related. Just from the technical standpoint one could assume the size of the power supply plays the biggest role here, but aural experience tells us there must be something else at work that is at least equally important. True, weak power supply doesn`t help here, yet after listening to numerous high quality amps I cannot help but conclude that the power supply responsiveness plays a critical role in this regard. I have heard numerous power amplifiers with monstrously over-sized power supplies but many of them lacked speed, control and authority, sounding dead, not alive. In the ultimate sense we are aiming for instant transient responsiveness and here I have noticed big differences among amps. Some are voiced for transparency, some for smoothness, some for neutrality (whatever that means), others for natural tone colors, etc. 


Bringing all the desired traits under one hood is not a trivial task. If we aim for those elusive live sound quality levels, then we have probably noticed, how besides micro and macro dynamics, live music possesses a kind of sound authority (weight) that even many of the really expensive audio systems fail to convey…and this is the second prerequisite for anywhere realistic sound reproduction.

UNDERSTANDING THE PURSUIT OF HIGH-END 


The preamps (or preamp sections in integrated amps) are supposed to deliver a signal that a power amp will give a meaning to. Of course there are power amps that are very (input signal) sensitive and might need just an attenuator but that is not the subject of this review.

If we understand the term HIGH END AUDIO literally then we are probably aiming for the absolute: wanting to get as close as possible to what we hear at live musical events. Of course END doesn`t mean we can get identical sound quality levels with high end audio equipment (nothing ever ends) In this case it just means we’re not interested in merely »good« sound.

The aforementioned »authority« (subjective weight) of the live sound is placing BIG demands on all components in the audio chain and is also showing the biggest differences among amplification. Sometimes it seems it is easy to achieve incredible transparency in the reproduced sound (not that it really is) and I have witnessed it many times, with high quality audio systems. Some components (or a combination of components) are like magnifying glasses, they can highlight tiny details in a way that cannot be heard with a live played instrument or a human voice. Although this might be attractive to some listeners – it is not a step closer to the live sound but a step away; we are substituting the real quality for an artificial one.


To make a reproduced music anywhere more realistic, we need to ensure the system will be able to preserve this AUTHORITY of the live sound as much as possible otherwise the reproduction will NEVER BE reminiscent of the REAL THING.

OK, so this brings us back to the subject of this review, the fabulous ACCUSTIC ARTS TUBE PREAMP II – MK2 and the ACCUSTIC ARTS MONOII monoblock power amps. Potent trio that excels precisely in the most difficult to reproduce areas: micro/ macro dynamics and authority of the sound – among many, many other things.

Throughout the years I have heard many great amps of different topologies and most of them were special in one regard or another but never offered so COMPLETE and OVERALL musically SATISFYING performance.

To begin with, the ACCUSTIC ARTS combo is able to drive ANY speaker with astonishing control, authority, showing incredible dynamic swings, fantastic levels of transparency, proper tonal colors, soundstage delineation and overall believability. That was a really short description. Now let us dig deeper.

My encounters with SoulSonic speakers, open baffle dipoles with tall ribbons showed me they have some special qualities that even lesser amps are able to reveal but it was only with the ACCUSTIC ARTS TUBE PREAMP II – MK2 and ACCUSTIC ARTS MONOII that I began to discover and fully appreciate all their virtues.

For instance, the lower and upper bass had qualities that just gave a much more convincing impression of the real thing. The beat of a kick drum was reproduced with a tremendous, uncompressed punch but the absence of box gave it a really lifelike feeling which was enchanting. Various big acoustic instruments like the big Kodo drums, upright basses or even pianos had a sense of authority that is rarely heard. This authority means the sound was powerful, dynamic and controlled at the same time; no instrument or voice was thinned or robbed of its weight. The piano, a very difficult instrument to reproduce, in particular sounded very dynamic and lifelike in its character. The instruments covering the midrange frequencies had a great definition with just the right timbre (especially with Skogrand Beethoven and Vovox Textura Fortis speaker cables). The solo vocals or choirs had tremendous clarity and natural, dense tonal colors with captivating openness that made the whole aural experience very intimate and called for prolonged listening sessions.

The guitar player`s chord movements were easily heard, yet still not highlighted in a negative way. They were just referenced according to how they were recorded.

The transparency was exemplary and this among other things led to a very holographic impression of the instruments placed on the imaginary soundstage.

The energy produced in live music was preserved extremely well; the reproduction was vibrant, immediate and ensured an incredibly emotionally dense and musically involving experience – a true rarity nowadays.


The combo showed no preferences for any musical genre, everything was reproduced coherently, stressless and very natural. Bad recordings were easily revealed, but not in a way that would diminish the musical enjoyment – quite on the contrary, for anyone who is a music lover first and foremost, this could be a dream system, with it, one could listen for all day long (even very loud) without any listening fatigue or sense of boredom.

I should mention that I have briefly tried to substitute the ACCUSTIC ARTS TUBE PREAMP II with some other preamps that I have had on hand. With the exception of Robert Koda Takumi K10 preamplifier none of them was able to serve the monoblocks in a proper fashion. The sense of energy and body was mostly lost and this further showed how difficult it is to find a proper preamplifer/power amplifier pairing.

CONCLUSION


ACCUSTIC ARTS Mono II power amplifiers and Tube Preamp II MK2 represent such a potent combination that leaves a lingering reference status and with the requested prices for both MonoII and Tube Preamp IIMK2, show a value that it’s not only hard to match, but quite unlikely to match.


The Accustic Arts trio could drive every speaker I have tried with absolute ease, however in combination with the SoulSonic Impulse speakers the ACCUSTIC ARTS Mono II power amplifiers and Tube Preamp II MK2 managed to create something special that operates at the level imagined by few. This combination reproduces the music at the “cost no object/au plus haut niveau” and brings a refreshing statement in the world of high-end audio.
When both ACCUSTIC ARTS Mono II power amplifiers and Tube Preamp II MK2 are working closely in a system with the SoulSonics Impulse speakers, they embrace the music and reproduce it with such realism that this must surely be widely acknowledged. And as such they are the recipients of the Upper Echelon Mono & Stereo award for not only being the state of the art audio products but also for being music machines capable of bringing the full emotional content hidden in the music grooves... and thus being able to satisfy the most discerning ears and highest demands. 


SAE GmbH & Co. KG
Hoher Steg 7
74348 Lauffen
Germany
Phone: +49 7133 97477-0
Fax: +49 7133 97477-40
Email: info@accusticarts.de




TUBE PREAMP II - MK 2:
· EUR 7990,- silver
· EUR 8190,- black

MONO II:
· EUR 12490,- silver (pair)
· EUR 12790,- black (pair)