Accustic Arts, the tradition-steeped company from Germany's south-western region of Swabia, is celebrating its 20th anniversary this year. While quickly gaining a good reputation in the Far East and also being there commercially successful, the prophet remained less prominent in his own country. As the Mono II prove, the products surely are not the ones to blame.

It was the former company management that held responsible for this by primarily having focussed on the export business. Then two years ago, Hans-Joachim Voss bought the company, and, of course, took the export business further on. In a second step, he is now concentrating on the German dealerships. And for this purpose he was able to win an experienced sales professional: Werner Möhring, also known as a member of the German distributor company “G8 And Friends”. Hans-Joachim Voss charged an open door when he suggested that I could again busy myself with gear from Accustic Arts: My positive attitude towards the company isn’t mainly based on the fact that right from the start the Swabians have had a great affinity to the recording scene and especially to sound engineer Milan Sajé, in which they found an experienced consultant, who not only works on his own or in Accustic Arts’ premises, but also for the renowned recording studio Bauer in Ludwigsburg. Milan Sajé accounts for the production of the five albums, "Uncompressed World Vol. I to Vol. V", released through Accustic Arts Audiophile Recordings, some of which are also available on vinyl. No no, even though I intensively shop-talked with Milan Sajé during my visit to Laufen in 2008 – by the way, I really do not have to be convinced of compression-free recording techniques – and though I could acquire a technical rarity from him at the time, it principally are the components, which have been justifying my positive attitude to Accustic Arts: Shortly after having done a company visit and a report thereafter, I had the opportunity – and the pleasure – to employ myself with the Accustic Arts Drive II and Tube DAC II. The mechanically immensely elaborate transport with its 18 kilograms of weight and the converter with the then quite unusual 32-bit signal processing technology and its tubed output section really wielded a sonically very lasting impression on me.

At the company's headquarters in Lauffen, located at the river Neckar, not only the production for all electronic components, the administration and sales, the warehouse, the test and measuring center, and the – already aforementioned – recording studio with separate recording room are to be found, but the development laboratory as well. Accustic Arts is used to work with different developers, depending on each type of component. Already one single component, such as a converter, requires the wide range of knowledge from electronics, digital and software specialists. However, the involvement of external experts does not necesserarily lead to arbitrariness. The developers do not only shape the components’ sound, but also ensure continuity. For example, the electronics specialist has been responsible for the circuit designs of all amplifier models since the company’s first days. Before I started the testing, he kindly agreed to provide by telephone some information, which is not to be found on the Accustic Arts homepage. By the way, the website also offers the explanation for the – at least to me – orthographically quite strange company name. In its completeness it reads „ACCUrate acouSTIC ARTS“, which reflects the company’s philosophy in full..

But let’s now go back to the Mono II, the second-largest amplifier in the Swabian’s reference line, which I have chosen because its opulent output power range of 300 watts at eight and 500 watts at four ohms is being more than enough for my system’s requirements. However, in contrast to the 60 kilograms of the top model Mono III, the Mono II only weighs “amicable” 25 kilograms. The discussion with the designer revealed that the Mono II despite its XLR input is not a balanced amplifier in its own right. If one selects the balanced input, the audio signal is converted into an un-balanced signal using an IC from Burr Brown and then treated in the same way like the signal entering the power amp through the RCA input. One could now begin to hotly dispute whether it would be better to lead the signal through the RCA output of Einstein's fully balanced The Preamp, thereby bypassing AccusticArts’ un-balancing circuitry or benefiting from the less susceptible balanced signal routing on the six meters long cables between pre and power amplifiers. Since there were no un-balanced signal cables around that could match the quality of my XLR connections, I will excuse myself from further musings on the matter, leaving everything the way it was by simply replacing Einstein’s The Poweramp with the two Accustic Arts Mono II.

After having passed the RCA input respectively the un-balancing circuitry, the signal is fed into a Burr Brown class A current amplifier. As Accustic Arts’ electronics designer explains, this is an extremely linear class A current mirror driver stage using six characteristic curve selected high-frequency transistors, which at the same time defines the relatively high bias current and the DC zero point for the twelve MOSFET power transistors selected in the same way. The power amp produces an astonishingly small percentage of distortion. In addition, 99% of the distortion spectrum consists of K2, aka harmonic distortion, which the ear perceives as pleasant. For the protection circuit, he defined a specific frequency curve in order to make a DC avoiding servo circuit at the output obsolete. Capacitors in the signal path he omitted as well. The capacitors next to the signal path are FKPs or polypropylene foil capacitors from Wima with a maximum tolerance of one percent. Except for the source and Boucherot resistors, only metal film resistors with a tolerance of one percent are used. Regarding the Boucherot resistors only metal oxide layer types with low inductivity and also a maximum deviation from the nominal value of one percent are allowed. All source resistors come up as low-inductance metal-band versions with ceramic housings.

A considerable effort is also applied to the power supply. The 1,200 VA toroidal mains transformer is manufactured according to Accustic Arts’ specifications and shows an additional copper band winding for statical screening, a potted structure, a MU metal magnetic shielding, and has separate windings for the positive and negative supply voltages for the MOSFET output stage, as well as for the input and driver stages. Their share of the total capacity of more than 80,000 microfarads is multiplied by a newly developed capacitance multiplier circuit similar to a gyrator. Ultra-fast switching diodes are used for rectifying both voltages. Although the Mono IIs admittedly have a high damping factor, it isn’t the absolute value – this is varying between 400 and 1000, depending on the measurement method – that’s got the highest priority for their developer, but more the fact that the damping factor stays linear beyond the audible range. This makes the work for the connected loudspeakers a lot easier.

Whereas my own work turns out to be a bit more strenuous when moving the quite heavy mono blocks from the photo studio into my listening room. However, these physical efforts quickly get rewarded when the first tones emerge from the still cold Accustic Arts monos: It is already audible that the monos will fit into my system seamlessly. There is no irritation, no irregularity. After all, this cannot be taken for granted, as all the components within my system, including a wide range of accessories, have been matched and harmonized for years. Before finally comparing them to my normally used power amplifiers, the Accustic Arts very much pleased my life for quite some time. They perform in such a right and familiar way, that I, without having to think about it, rely on them when testing the Aqvox Detoxer. On one hand, they set to work with high resolution, which makes working with them an extraordinary experience, and on the other hand, they act so harmoniously and homogeneously, that one wants to listen to them for mere pleasure. In the course of time, a further noteworthy detail comes to my mind: the monos real have a good grip on the woofers of the Kawero!, which must in no way lead to the impression of a somewhat more slender bass foundation. On the contrary! The Mono II combines the best of both worlds: lots of energy and precise control.

I must say that I already forgot about the fact, that the Accustic Arts monos had been responsible for my chain’s powerful performance, when I played Helmut Baumgartner a few recently rediscovered rock songs before he addressed his studio work. However, the amplifiers delighted him much more than the harsh, barely audiophile rock sounds – and that for a reason that seemed to have lost my attention because of the successful integration of those monos in my system: The ones from Accustic Arts are different from the Ayons with their nominal 150 watts or from Einsteins The Poweramp with its 140 watts, both into 4 ohms, being comparatively true power packs with their 500 watts at 4 ohms. In practice, however, when increasing the power rating of solid-state power amps, it at the same time gets increasingly difficult to have them sounding smooth and harmonious also in the high-frequencies, wherefore Helmut Baumgartner got extremely positively surprised by the finely resolved, yet entirely stress-free and enjoyable high-frequencies, in light of the Mono II’s interior with its twelve power transistors and the mighty toroidal mains transformer. I like to admit that I headed for the Mono IIs without any expectation – or should I better write: quite naive? Having heard my colleague’s comment, I suddenly had to think back with frights to the review of the gorgeous Göbel Epoque Fine, whose impedance drop put the Brinkmann monos used for amplification at that time out of range. The replacement amps, which were then hastily cobbled together to complete the pending final sonic impressions, were probably the strongest and most expensive amplifiers that ever found their way into my listening room. They had an easy play with the Epoque, but by no means they were able to reach the musicality of the stressed Brinkmanns. Since then, I nurtured a certain skepticism about extremly powerful amplifiers in general. The Mono IIs, however, I gave a listen even before I occupied myself with their technical specifications. They simply sound like extraordinary delicate power amplifiers paired with a moderate power rating – despite their specs showing those impressive 500 watts. Awesome!

Before starting the comparison with The Poweramp, I take care in putting up the best possible working conditions for the Accustic Arts monos: Since they source their power, like all other power amps in my listening room, through the tried and tested power cables from Swisscables Reference Plus there is no other field of play left than to improve the positioning on the floor. At present, the Harmonix Beau Tone Million (TU-666M) rank as my favorites. Up to now, they have managed to lift all used power amps to great sonic heights. But one of the two sets that I have in my possession, I use under the Kawero! Classic, so I switch to the second best in my list of favorites, the Beau Tone (TU-666ZX). While the Mono IIs are placed directly on the tiled floor, Arild Anderson's "If You Look" from the album If You Look Far Enough enthuses with richly colored percussion instruments, powerful kettledrums and perilous sounding electronic sounds. The Hamonix feet, though, help them to a much wider and somewhat deeper virtual soundstage. The distinction between the smaller bells, bigger bells and rattles now works out even better: The instruments seem to be playing in the room, the speakers vanish and cannot be located anymore. Truly good!

In comparison with Einstein's The Poweramp there is not much of a quality difference, the sonic discrepancies linger in the range of nuances: The Poweramp performs a touch faster and minimally warmer, whereas the Accustic Arts manage to open up a soundstage at least as large and open, if not more widely spaced. The solid-state monos also indulge with minimal more pressure and control in the lows, but the temperature in the recording room seems to be one or two degrees lower. As you can guess it, this is about very subtle matters of taste. Far less subtle are the differences in power rating that the Mono II and Einsteins are able to offer. I must say, I am perfectly happy with both!