he bottom panel of the electronics module mounted on the Zero 1 PRO speaker’s rear baffle features an identification plate. In addition to information about the place of manufacturing – here Avantgarde’s new large factory in Reichenbach (Lautertal), Germany – we also find a cleverly given serial number. The speakers that came to me after initial break-in at the manufacturer and then by the distributor were labeled as "ZERO.0008". This made them one of the first Zero 1 PRO pairs that had ever been assembled.
The very first one went to the High End Show in Munich, where it made a great impression. Awarded by “High Fidelity” the Best Sound High End 2013, the speakers are indeed extraordinary. And it’s not the kind of extraordinariness that we got used to and that is associated with “otherness”, but rather a real, solid, technologically-based “grand extraordinariness”. To come to this, however, first we need to take a closer look at them and find out what is behind their smooth, white or black, finish.

We ought to start as the manufacturer does in the information brochure, which is “from the beginning”. The Zero 1 PRO is a horn-loaded, three-way active speaker system. Each of the two horn driver units is driven by a separate 50-watt X50 amplifier, and the woofer by a powerful 400-watt Class D amplifier. The midrange and treble units operate in pure class A, with zero negative feedback and fed from the power supply taken directly from the XA power amp. Power to them is so often filtered, and the control system has stabilized power supply. The sensitivity of the midrange and tweeter drivers is high - as with horns - and reaches 104dB. It's just that we are familiar with that from many other designs. Yet even here we can point to certain characteristics that are unique to this product. First of all, its size.
Horn speakers are large by definition. Their size can of course be modified and there are attempts to scale it down, as reflected in the Uno Fino (see my review for “EnjoyTheMusic.com” HERE), yet classic horn speakers are large or very large. In comparison, the Zero 1 PRO appear like a miracle, with their front baffle almost exactly the same size as my stand-mount Harbeth M40.1. That alone is a great achievement. Yet it is when we look at the speaker from the side that we clutch our heads and ask, where the hell the subwoofer enclosure has gone? The speakers are no deeper than an Ikea bookshelf in its carton packing. And these woofers are some powerful 300 mm beasts, boasting the low frequency range of 30Hz (at -3dB). Such miracles have been made possible by harnessing the power of digital circuits.

Speaking in Munich with Armin Krauss, whom you should easily recognize (each year during the Audio Show in Warsaw he’s the Avantgarde presenter who likes to play Rammstein at a concert-level volume), I couldn’t help but notice that describing the new project he spent most of the time to explain an innovative formula of the whole system. We are quite familiar, as he said, with active speakers as such – just have a look at the D’appo from the Polish manufacturer Sveda Audio. Active speakers are fed by a line-level signal straight from a preamplifier or sound source, which is then crossed over in an active crossover network and amplified separately for each driver unit. The Zero 1 PRO is different as it accepts a digital signal that is first processed in that form by D/A converters before going to analog amplifiers.
The speaker features an active crossover but signal processing is carried out in the digital domain. The manufacturer has employed here 66-bit FPGA-based processing that offers high performance, with precision down to 10Hz. Finite Impulse Response (FIR) filters guarantee outstanding impulse response for each of the three converters. Avantgarde engineers managed to shape the filters in the way that gives them almost perfect phase characteristics (with deviation of less than 5 degrees in the PRO version) and nearly absolute synchronicity. Digital filters usually have very steep characteristic to effectively divide the range between the drivers. Many designers and music enthusiasts believe that the best results are achieved with the least steep of the available filters, a first order crossover of 6 dB per octave. Avantgarde subscribes to this view and comes up with a progressive steepness filter. A 6 dB filter is used at the crossover point, which then becomes progressively steeper until 100dB at the cut-off point.

We know, therefore, that the Zero 1 PRO is an active three-way speaker with a digital crossover. It stands to reason that the signal used to feed them should also be digital. And so it is. The whole electronic circuit, including amplifiers, is housed in an aluminum cast enclosure mounted to the rear baffle and covered with a nice grille. From below we can plug in a USB or Toslink cable, two digital S/PDIF cables and one AES/EBU – in other words nearly all existing standards. If we want to use WLAN transmission, we need to connect to the Toslink input a suitable receiver, such as AirPort Express.
The signal is fed to one speaker, which serves as the master. The other is the slave speaker that receives a 16-bit, 44.1 kHz digital signal over the air. During our conversation, Armin Krauss devoted much time to describing this wireless signal transfer between the speakers and the measures taken to minimize distortion. This was a priority in developing a proprietary transfer protocol. The transmitter operates at the frequency of 2.4 GHz. However, if you believe (like me) that nothing beats the wire, an Ethernet cable can be used to connect the speakers with each other. The wireless transmitter then turns off automatically. An interesting fact is that the speakers are available in two versions that differ only in software. The “cheaper” (named Zero 1) sells for 9,900 Euro per pair, while the pair of the more expensive Zero 1 PRO sets you back 11,500 Euro. Which shows what is the real cost these days – the software. The more expensive version has been designed for no-compromise audio and employs the “minimum phase” software, responsible for its shockingly low phase shift. The less expensive speaker is no slouch, either, but its performance is slightly inferior. We are reviewing the PRO version.

Technology is the key here, as this is what defines the Zero 1 PRO. Equally important, however, is its user friendliness, which is respecting the time and frustration of people who want to use these speakers for listening to music. The rule is that the less time we spend on connecting and calibrating the system, the more we can spend on listening. And music is always the winner. The speakers from the company headed by Holger Fromme are one of the most technically complex audio systems available and they are at the same time the easiest to use. They are essentially maintenance free. You pay money for that but nothing in life is free.
Technology and user friendliness are both incredibly important. Yet it is very likely that these speakers’ “to be or not to be” will be decided by their form. Horn speakers are associated with large dimensions, imposed by large horn mouths. AA offers them in any size and color. They always dominate the room interior and draw attention. They are not really visible at first sight in the Zero 1 PRO. Their cabinet is very shallow, the reason being that the front baffle also doubles as the tweeter’s and midrange driver’s horn mouths, as well as the woofer’s mounting point. Classic AA designs employ mechanical phase alignment of the two former drivers by their appropriate placement relative to each other. Here, the same operation is performed on the signal, in the digital domain, which makes it possible to position the speakers as shown in the pictures. The electronic modules mounted to the real baffle are housed in solid aluminum alloy casts, resembling the XA-line amplifiers’ heat sinks, with connectors placed on the bottom side (only the master speaker features input connectors). However, in order not to disturb excellent stylistic consistency they are covered with magnet-fitted grilles made of ABS polymer, the same as that used for the cabinets. The speakers are tilted back a few degrees and sit on rigid stands made of chromed flat bars. They look amazing.

Albums used during auditions

CDs

• Jesteś Bogiem, soundtrack, Magic Records 3719533, CD (2012).
• Mission, Cecilia Bartoli, Decca/Universal Music LLC (Japan) UCCD-9885, SHM-CD + DVD (2012).
• Vivaldi con moto, Carmignola, Academia Bizantina, Dantone, Deutsche Grammophon/Archiv Produktion/Universal Music LLC (Japan) UCCA-1099, SHM-CD (2013).
• Alan Parsons Project, I Robot, Arista/Sony Music Japan SICP 30168, “Legacy Edition”, 2 x BSCD2 (1977/2013).
• Antonio Caldara, Maddalena ai piedi di Cristo, René Jacobs, Schola Cantorum Basiliensis, Harmonia Mundi France HMC 905222, 2 x CD (1996/2002).
• Black Sabbath, 13, Vertigo/Universal Music LLC (Japan) UICN-1034/5, 2 x SHM-CD (2013).
• Depeche Mode, Enjoy The Music....04, Mute XLCDBONG34, maxi-SP (2004).
• Enya, Enya, BBC Entertainment BBC CD 605, CD (1987).
• Nat “King” Cole, Welcome to the Club, Columbia/Audio Fidelity AFZ 153, SACD/CD (1959/2013).
• Ornette Coleman, The Shape of Jazz to Come, Atlantic Records/ORG Music ORGM-1081, SACD/CD (1959/2013).
• Richard Strauss, Also sprach Zarathustra, dyr. Zubin Mehta, wyk. Los Angeles Philharmonic, Decca/Lasting Impression Music LIM K2HD 035, K2HD CD (1968/2008).
• Siekiera, ”Nowa Aleksandria”, Tonpress/MTJ cd 90241, 2 x CD (1986/2012).

Audio files

• SATRI Reference Recordings Vol. 2, Bakoon Products, FLAC 24/192.
• Charlie Haden & Antonio Forcione, Heartplay, Naim Label, 24/96 FLAC, źródło: NaimLabel.
• Dead Can Dance, Anastasis, [PIAS] Entertainment Group, PIASR311CDX, "Special Edition Hardbound Box Set", CD+USB drive 24/44,1 WAV (2012);
• Depeche Mode, Black Celebration, Mute DMCD5, “Collectors Edition”, WAV 24/48 (1986/2007).
• Depeche Mode, Delta Machine, Columbia Records/Sony Music Japan SICP-3783-4, FLAC 24/44,1, źródło: HDTracks (2013);
• Miles Davis, Tutu, Warner Brothers Records, FLAC 24/96, źródło: HDTracks.
• Nagrania z płyt DVD-R pisma “Net Audio”.
• Persy Grainger, Lincolnshire Posy, Dallas Wind Symphony, dyr. Jerry Junkin, Reference Recordings, HR-117, HRx, 24/176,4 WAV, DVD-R (2009).
• Yes, Close to the Edge, Warner Music, FLAC 24/192, źródło: HDTracks (1972/2007).

Japanese editions of CDs and SACDs are available from

The Avantgarde Acoustic loudspeakers communicate with each other via a radio link. They only need to be hooked up to the mains with the digital input of the master loudspeaker connected to the music signal (e.g. via AirPort Express). That's it.
(Avantgarde Acoustic product literature, see HERE)

It’s all true. Although manufacturers of advanced digital equipment write about “user-friendly”, “smooth” and “nice” operation of their devices, this is almost always more wishful thinking than reality. In practice, the number of steps required to get the sound from an audio device having anything to do with computers and digital sources seems to be growing exponentially with their capabilities. Thus, quite unexpectedly, CD and SACD players turn into a symbol of true ease of use and reliability. Even a PhD degree in computer science does not guarantee you will get the sound straight after unpacking the unit, and any setup change will almost certainly make you repeat the installation process. That is one of the reasons why I think of computer as a valuable but bothersome sound source. It has no “play” button and all too often I have to go to extra lengths to force any sound out of it at all. For me it’s a waste of time.
Avantgarde speakers are a real “"plug and play”. Within the first ten minutes I managed to have them unpacked and set up. Their positioning does not take too much time and they actually sounded best placed in the very same spot once taken by the Uno Fino and earlier by the Uno Picco. You just need to make sure that the tweeter is directed towards your ears and the closer you sit the more the speaker needs to be tilted back. Connecting the power cords and the signal source takes another five to ten minutes. In my case, the sources were the Ancient Audio CD player equipped with the Philips CD Pro-2 drive and my PC, with the signal sent via USB. The Zero 1 PRO USB receiver accepts 16-bit/44.1kHz (and 48 kHz) signal and does not require any software driver. Other inputs are up to 24/192 capable. It takes only half an hour, from speakers’ delivery to our door to opening a bottle of wine, before we can listen to music.

We will immediately know we’re listening to Avantgarde speakers. The Zero 1 PRO sound in the way that is hard to mistake for anything else. Their sound is extremely dynamic. The German manufacturer has accustomed us to that and it hardly makes much of an impression on anyone. It’s simply the way it is and that’s it. The problem is to switch back to classic designs which, by contrast, seem slow and sluggish. Only magnetostatic and some electrostatic speakers combine speed and tonality in the way that the Zero 1 PRO, and in further perspective all speaker designs from Reichenbach, do. The longer I listened to the reviewed speakers the better I profiled my musical choices, and the more distinct was the similarity of my “playlist” to what I usually listen to on my HiFiMAN HE-6 magnetostatic headphones.

What stood out first were classical music recordings. Almost all the speakers I know have a problem with them. Or many problems at once. Some more pronounced, other better disguised, but in general almost all tend to get lost and do not show the detail and the whole equally well at the same time, usually focusing on one or the other.

The Zero 1 PRO, just like the HiFiMAN headphones, are capable of both simultaneously. Their sound is detailed and coherent at the same time, thus showing the whole music event. If we want to, we focus our attention on any instrument, artist or their group, and if don’t, we can “move away” and listen to the whole orchestra. It came intensely into play in the Prologue from Also Sprach Zarathustra. The opening low rumble was not merging together into one because it was conveyed as consisting of a variety of small components. Yet they were only audible when I was drawing my attention to this or that. I remember Damian Lipinski, who is responsible for Savage’s CD remasters, talk how he was surprised that each sound (instrument) on this musician’s recordings came from layering several and sometimes even dozen tracks together. A simple snare was composed of a dozen separate strokes. But it is only audible on a good audio system, i.e. the sound is rich and multi-layered. On a poor system it’s just a strange sounding snare (see HERE). The Avantgarde coped very well with it. The sound on Also… was quiet, like the double basses closing this part, but when the orchestra played forte everything developed immediately and sounded very loud and extremely fast. This level of dynamics and selectivity cannot be faked, and only stage audio systems and large studio (active) speakers are capable of sounding that way. No wonder Armin often plays Rammstein.

But it is not only dynamics and excellent selectivity that will surprise us in such an unusual combination. They do not exist just for themselves but are only a base for coherence. The company literature talks much about nearly perfect phase characteristics of the D/A converters and the digital crossovers are excellent in this respect, at least in theory. I must say I have probably not heard any digitally filtered speakers that sounded like the Avantgarde. It’s not a perfect design, nor aspiring to be one for all I know. But we get here all the things that the manufacturer promises. And the time coherence I mention translates into an incredible tangible sound.
The lower midrange seems almost warm. The speakers do not sound warm, quite on the contrary (about which soon), but it may appear so. This is caused by the lack of any irritating components and the elimination of some kind of sonic “wobble”, a more or less annoying artifact that is, however, quickly recognizable. Classic speakers usually conceal it because their sound is slow. The Zero 1 PRO impulse response must be incredible because we can hardly hear the attack – it simply is there. Electrostatic speakers, also very fast, very often emphasize and harden the attack, while classic speakers tend to round it. Then it can be heard. The Avantgarde horns do not draw our attention to it, letting us focus instead on the full bodied sound.

The latter is felt differently than I am used to. The sound is projected by the Zero 1 PRO on the speaker line and in front of it, in an incredibly vivid and tangible way. The soundstage depth is only slightly marked. That is partly why everything seems to be fleshy. But that is only the beginning. The real ride begins when we realize that everything can be heard here. A conundrum, isn’t it? After all, selectivity implies something just like that and there seems nothing to talk about. It only seems so, though. As a matter of fact, selectivity describes how the elements that are sonically different, such as instruments, human voices, acoustic characteristics, and even various parts of larger instruments, are separated from each other, and how exactly the difference between them is shown. What I would like to say in the context of the reviewed speakers is something else still, not even associated with resolution, which is not better than in passive speakers from the same price range. I think of something that gives us vividness without rounding the attack, without withdrawing treble and without minimizing the amount of detail. Each of them leads to a vivid presentation, but each one also irreparably distorts the sound. The Zero 1 PRO sound “immediate”, if I may say so. Speed ​​is one thing, but the other is a sort of an orderly universe, a here-and-now sound without looking for sounds getting slowly out of the background, while on the other hand without cowering before sonic urgency, sharpness and aggressive attack. Here everything fits together; the sounds, instruments and planes do not fight each other but have their inner “communication” that is invisible yet synchronizing everything. I have not heard that in any other speakers from this manufacturer. Actually, I rarely ever hear such a thing.

The speakers under review are similar to the Uno Fino, one of the better sounding speakers from Avantgarde – in my opinion, of course – in dynamics, speed, frequency range, selectivity and soundstage. On the other hand, they resemble my all-time favorite but no longer manufactured Uno Picco with their understanding of the presentation as a coherent structure, a grid with finish superimposed on top. And what I wrote earlier is simply unique to them. However, one needs to be aware that they are one of the less expensive speakers in this manufacturer’s product lineup. If we take into account that we get here a pair of three-way speakers with – say – active bass (as in other AA speakers), together with two stereo Class A amplifiers, a stereo (that’s how it can be viewed – it converts stereo signal) DAC, and active crossover to boot, then there is no use expecting them to sound at the same level as more expensive speakers with active bass that still need a power amplifier, preamplifier and DAC. What is the difference between such systems? First of all, resolution. Secondly, bass definition. And thirdly – soundstage. What is surprising, however, is not what we just said – that happens to be absolutely normal. It is so and that’s it. The real surprise is the degree of similarity of the Zero 1 PRO to flagship designs from this manufacturer. I think first of all about tonality.

Horn speakers cannot be mistaken for any others. Their strength lies in the immediacy of energy transmission, which is perceived as more accurately rendered textures, better dynamics and generally superior differentiation. Their resolution is not particularly impressive; selectivity comes out much better. The Numero uno, however, are all about the midrange presentation. If classic speakers sounded similar, I would say that their upper midrange is stronger than what is below. Here it is interpreted as part of a larger package. It’s a bit like ‘temperature’ and the so-called ‘perceptible temperature’. While the thermometer shows a certain reading in winter, the temperature we actually perceive can be a few or even dozen degrees lower, depending on wind chill and air humidity. In classical speakers, emphasizing the upper midrange is perceived unambiguously as something wrong, very wrong! The Avantgarde show that range in a way that is like opening the window. We get sounds along with reverb and accompanying acoustics, immediate and instant. I think it’s more about speed rather than emphasizing the midrange. It seems stronger to us because we are used to a different presentation. The top end is pretty sweet and detailed, although it does not draw our attention unless an instrument happens to venture into this region or the producer plays with counter-phase. Then it immediately jumps into our field of vision. The bass is strong, low and fleshy. Its low extension is amazing, especially with such a small cabinet capacity. It is here that the wonders of digital processing are best heard. However, the upper bass is not as saturated and full as in classic speakers. It is better defined than the bottom end but also a little more distant. Such karma. And technology limitations.

Conclusion

Writing about the sound of these speakers is lots of fun. Yet I wouldn’t be quite fair if I said that that’s what’s most important about them. Everything is in its place, the speakers play with panache and perfectly scale the sound to the listening room size. Auditioned in Munich in a 50-meter hall they played with a greater volume and forward momentum than at my room, placed about 2.5 meters from the listening position. I found no problems with the bass. Everything was simply slightly smaller than in the large hall. In this respect, they are phenomenal. They also have something about them that makes us listen to music with interest, waiting for what’s coming next – a rather important feature in audio, isn’t it? However, in my opinion, the strength of this design lies in its form combined with the ease of use and only then supported by the sound. Their outer form is truly amazing. The speakers remind me the monolith from 2001: A Space Odyssey by Stanley Kubrick (1968), and the curvature of the horns perfectly matches the rest of the cabinet shape. Connecting them to the audio system is piece of cake and everyone can do it. The Zero 1 PRO do not require any in-depth knowledge of electronic equipment to use them. It’s a world championship. There will be no sudden software “glitch” nor will we “lose” connection. The speakers resemble in that my ideal piece of audio gear, the CD player.
What would I change in them? There are two things that – had I had a magic wand – I would have done differently. I would design the remote control to display the volume level and selected source. Groping around, without knowing how much the speaker was “turned up” was quite frustrating for me. I would also prefer the speakers to transmit the signal with higher than 16-bit resolution between each other. That is the only playback quality they are – in fact – capable of. But these are just my wishes and each user will probably have their own. Against everything that the Zero 1 PRO CAN DO they are just the grumbling of an old audio enthusiast.

On the technical side, the Zero 1 PRO is a complex system that can, however, be broken up into relatively simple factors. These are much easier to describe. It is a three-way active speaker design. The 25mm tweeter and the 125 mm midrange driver are horn loaded to increase their sensitivity. The horn diameter of the former is 130 mm and of the latter is 400 mm. Their configuration is reversed, i.e. the tweeter horn is below the midrange horn. The woofer is loaded classically into a vented enclosure. The port is a gap on the rear baffle. The 300 mm woofer driver has a paper cone supported by stiff folds of impregnated fabric. The woofer is covered with a grille made of gray fabric stretched on a plastic, pretty stiff frame. The speakers are tilted back and the angle can be adjusted for their proper phase alignment. They ought to be positioned so that the tweeter radiates towards our ears.
This, however, is not the only adjustment we can do. The rear baffle sports a row of DIP switches to set the subwoofer gain level. For me, the best setting was +4 dB.

The electronics is mounted on a large circuit board bolted to a solid, big, heavy cast, working as a heat sink. Its form resembles that of a car amplifier, only better built. Each speaker is equipped with one such module, but only one of them sports inputs connectors. We have at our disposal two electrical S/PDIF RCA inputs, Toslink optical input, USB input (16/44.1/48) and AES/EBU. In addition there is an Ethernet port. The latter, however, is not used to connect the speaker to the Internet (which more and more companies choose to do, thus having the option of remote equipment maintenance), but for alternative connection between the speakers. As the digital signal is fed to only one of them, it is transmitted wirelessly to the other. It can also be done in a traditional way, via Ethernet cable. A careful look will reveal a pair of balanced analog inputs. This option will be available very soon, allowing to connect the system to analog audio sources. Inside, there is a suitable place for mounting the board with A/D converter.

As it turns out, the electronics is mounted in a modular fashion using both manufacturer’s own “blocks” and components from Hypex Electronics BV. The digital signal is fed into the main board housing the digital receiver, USB-S/PDIF converter and FPGA unit that carries out the calculations. The USB receiver is the well-known TAS1020 chip capable of handling the signal up to 24-bit and 96 kHz. The fact that it is limited here to CD quality is due to design choices. The electrical inputs feature impedance matching and isolating transformers. After selecting the active input the signal first goes to the AKM4113 digital receiver and then to two AD1895 stereo frequency converters that convert any input signal to one that is accepted by the adjacent big FPGA chip. After processing, the signal is sent to a separate board with the actual digital-to-analog converter, a four-channel Burr Brown PCM4104. And only from there it gets to the two amplifier modules mounted on separate boards. The upper- and mid-range is handled by a classic Class A solid state amplifier. It is based on two medium-sized complementary transistor pairs per channel. The PCB sports excellent high-power Dale resistors, Wima, Elna and Nichicon capacitors – no money was spared. The bass is handled by an amplifier module from Hypex Electronics BV, the UcD400 in OEM version. The amplifier has its own switching power supply, also from Hypex. The other two amplifiers share a common switching power supply, with much more complex circuit. Due to its modular design, I can easily imagine a future system upgrade of any of its sections.