The Amethyst corrector preamplifier is the most sophisticated high-fidelity control electronics on the market today. The inventory of its possibilities and connectivity could certainly have inspired Jacques Prévert. Compared with the ST2-Hifi, which introduced the young French company to the world of home audio in 2010, the Amethyst unveiled in 2012 proves to be much more versatile, while retaining the lethal weapon of its predecessor, namely parameterizable acoustic correction based on Trinnov Audio’s patented technology.
As a preamplifier, converter, active crossover and acoustic corrector, the Amethyst can be controlled via the display and two facial knobs or its remote control, via a PC, Mac, smartphone, or tablet compatible with Windows, iOS or Android over an Ethernet network or Wi-Fi, via a Crestron remote control or via RS-232, no less! The Amethyst looks just like the electronics we’ve all dreamed of, but never dared to ask for. High-fidelity system owners who want to do away with the problems of cabling, room acoustics and piles of equipment, unite, or rather relax, because the Amethyst is here to simplify your audiophile life, for the better.
The room, the unknown
One of the major and fundamental problems encountered by most installations is, and remains, room acoustics. The most striking example is that of trade shows, where listening rooms are generally not acoustically conducive to clean reproduction. Some exhibitors nevertheless make the effort to treat their listening rooms with absorbent or diffusing panels, but most fail to do so for lack of time. What follows are random demonstrations of room resonances, tonics, and other interferences. A profusion of resources for a sound flop when a proper acoustic treatment would undoubtedly have reversed the trend. But the pot calling the kettle black: if inquisitive visitors to trade fairs have an easy time of it, how many of them, and consequently how many of us, have implemented a plausible acoustic treatment at home? A system, no matter how high-end, will only be a shadow of its former self if the room acoustics have not been mastered. These acoustics can be treated either passively, as mentioned above, with the precise placement of panels, bass traps and other sound traps in the room, or actively with electronics such as the Amethyst.
Active correction
Room acoustics are first and foremost a question of coherent sound propagation. Even before talking about treatment, it’s easier to spread sound in a healthy environment that doesn’t distort the sound or spreads it according to a precise pattern. A cinema, a concert hall, an amphitheater or, at the dawn of time, an ancient theater, all these places are or were designed in terms of proportions and materials to propagate sound according to specific criteria. A living room in an apartment or a house would be completely different. What’s more, when you install an audio system, you want to reproduce the entire audible spectrum as linearly as possible. The equation borders on the insoluble… The professional world has adopted passive and active processing through parametric analog equalization and then digital processing, a field in which Trinnov Audio has crossed its first swords. For a long time, high-fidelity speakers held back from these effective solutions, judging the acoustic panel to be unattractive and the electronic correction to be far removed from the straight line with gain. The arrival of digital correction in the early 2000s, with Tact in particular, opened up new avenues, offering tenfold adjustment possibilities. Trinnov’s ST2-Hifi had benefited from the considerable technological advances made over the last twenty years, and from the experience accumulated by the manufacturer in professional circles, to set a new consumer benchmark in active acoustic correction. The Amethyst is even more in line with music lovers’ expectations.
Hello microphone!
What sets the Amethyst apart from all other corrective preamplifiers on the planet is its unique microphone, which allows measurements in all three dimensions. It consists of four capsules, each mounted at the top of a brass tube and all resting on a cylindrical body to form a tetrahedron (three-sided pyramid). Calibration measurement resolution (speaker distance, height and spacing) is plus or minus 2° in all directions. Compared with the ST2-Hifi, once the microphone has been set up in the listening position and at ear level, calibration is simplified thanks to a calibration assistance menu. This step-by-step menu guides the user through an initial optimization in just a few minutes, generating five settings – Comfort, Natural, Neutral, Precision and Monitoring – in line with the type of listening required. It all starts with the room impulse response for each speaker. The Amethyst software then calculates the filtering that will counterbalance room effects such as primary reflections and reverberation time, and speaker non-linearities. This filter proposal is then applied in real time. In any case, a correction filter acts with a sound effect, however slight, that can modify the system’s signature. So, in addition to the five basic settings, the device offers the possibility of fine-tuning the response frequency, phase, and delay of the filtering by means of twenty-nine “presets” that can be memorized by the user, aided in his choices by the initial calibration. It’s worth noting that the Amethyst’s ability to consider the overall “acoustic field” in the room helps create a correction that remains effective even if the listener moves around the sweet spot. At low frequencies, Trinnov reduces the influence of resonance modes below 300 Hz by introducing a compensation filter for each detected mode. It also analyzes the room’s frequency response for colorations generated by room reverberations in the midrange and treble. These colorations are reduced by filtering. And to make all this in-depth work a reality, the Amethyst provides a battery of measurement curves (amplitude-frequency, phase-frequency, impulse response, etc.) that can be downloaded onto a simple USB key to visualize its corrective effects. Finally, an important feature of the Amethyst is its 2D/3D Remapping technology for virtual speaker repositioning. Based on the calculation of the acoustic emission produced by each loudspeaker, and on the notion of spherical harmonics (Fourier-Bessel decomposition), the process calculates the ideal position of the loudspeakers (Ideal Radiation Matrix) in the listening room, in order to achieve coherent spatial diffusion in tune with the musical content. In the case of an unsuitable room where the speakers cannot be ideally positioned, the Amethyst defines the correction to be made to the input signal (Remapping Matrix) to recreate an ideal acoustic emission.
And the music was
After acoustic optimization, it’s time to listen to the Amethyst within the system. Connectivity is extensive, with no less than eleven inputs and four outputs, both analog and digital. Knowing that the Trinnov has two internal converters, one A/D and one D/A, we can guess that it can convert an incoming signal from one format to the other, and vice versa. It also has the ability to combine analog outputs in different configurations, including one for biamplification. Hence the presence of an active filter that emulates various selectable structures in the digital domain (Bessel, Linkwitz-Riley and Butterworth up to 4th order). One of the analog inputs can be switched either to line level or to MM phono input, called HybriD Phono. The term HybriD refers to the fact that the highly innovative RIAA correction is built around an analog scheme for bass and low midrange up to 1 kHz, then digital processing with a dedicated algorithm takes care of the kilohertz aftermath. The Amethyst can also be used as a network renderer using the UPnP protocol, so it can receive PCM files (WAV, AIFF, OGG and FLAC) up to 24/192 via Wi-Fi or wired via its Ethernet port. It thus acts as a slave on the network, with the server providing its library as a master. Finally, the presence of a clock input means that the Amethyst can be synchronized by an external clock encoded on an S/PDIF or AES/EBU source to be defined in the device’s programming menu. In master mode, the Amethyst’s default mode, all data is resynchronized by the internal clock, and a buffer prevents loss of synchronization with the incoming signal. A few details before concluding. The analog and digital audio stages are supplied by a linear power supply (toroidal transformer, filtering, and regulation), while the other electronic sections are supplied by a switch-mode power supply, and inputs are switched by relays. A fine piece of work for electronics designed and built in France.
THE SET UP
Contrary to popular belief, the Amethyst is extremely simple to set up, taking no more than half an hour. Purchasers can, of course, ask their dealer to carry out the operation. We were lucky enough to benefit from an on-site demonstration by Antonine Galipon, Trinnov’s highly professional ambassador, who was kind enough to explain all the subtleties of her machine to us. And once the network connection has been made, the control interface installed, and the part calibrated with the ad hoc microphone, all that’s left to do is sit back and enjoy the wide-ranging possibilities of this remarkable machine.
THE SOUND
The Amethyst already behaves like an excellent preamplifier-converter, without its acoustic corrector even coming into play, and it doesn’t fall short in the least for the price it’s offered at. It features natural sound reproduction and wide bandwidth. The sound is magnificently clean, fluid and light, fast and serene. The spectrum is rendered with perfect articulation, marked presence, and above all an “invisible” transition between the different registers, much like a very good full-range amplifier. Neutrality and responsiveness. Next, we switch on the Acoustic Corrector, and enter a world we didn’t even know existed. In fact, just a few seconds before, we were already satisfied with what we heard. But thanks to 2D/3D remapping, we realize that the system’s scope for improvement is just incredible. First, the “new” listening surprises us by its anti-spectacular character. It’s as if we’d turned down many of the sliders on a gigantic equalizer. Except that in this case, the selection is masterfully judicious. All the frequencies that previously tended to color the signal are readjusted to offer an infinitely more natural, clearer, and unexpectedly accurate sound. And this analysis is carried out on a single piano disc (Alicia de la rocha, Granados)! In fact, we go back and forth several times, with and without the corrector, to analyze what’s going on. We have the same sensation as if the speakers had been positioned in an absolutely ideal way in the room, in defiance of all rules of domestic comfort, but also that the room would have been acoustically treated in an ideal way, which in both cases is incompatible with family life; 90% of systems, even top-of-the-range ones, are in living rooms!
What was obvious with a solo piano is even more obvious with a symphony orchestra. The London Symphony Orchestra performing Maurice Ravel’s Rapsodie Espagnole under the baton of Claudio Abbado is a real treat for the senses. It’s one of the very first times we’ve felt so strongly immersed in the sound recording venue. We’re in the room. The dynamic contrasts are mind-blowing. The revs are lightning-fast. And all this with astonishing smoothness, thanks to a total absence of distortion and compression. The system seems totally liberated. Moreover, while ProAc are remarkable monitors, they don’t produce any real extreme bass, and the Amethyst manages this very well too, achieving a perfect optimization between the characteristics of the room and the speakers. On a purely electronic 24-bit native range (Granite by Martin Nonstatic), the bass presence is palpable and physical. The degree of bass analysis is surprisingly precise. It’s like listening to headphones, with the added physical pressure. Of course, the Amethyst allows us to listen (much) louder, with much greater comfort. Not a good point for neighborly relations, but a particularly obvious indication of the system’s good health… We could multiply the examples and extend the list of benefits of this miraculous machine. Admittedly, at €10,000, the Amethyst isn’t cheap, BUT let’s not forget that it combines the functionalities of 4 links (preamp, DAC, network player and acoustic corrector), that it’s pretty, pleasant to use, very well made, and French to boot. So no, I tell you, the Amethyst is a DEAL.
TECHNICAL SHEET
PRICE
€ 9.990
DIMENSIONS
442 x 103 x 445 mm
WEIGHT
10 kg
RESOLUTION
24/96 (A/D conversion), 24/192 (D/A conversion)
SIGNAL-TO-NOISE
> 119 dB (A/D), > 118 dB (D/A)
JITTER RATE
> 50 dB above 100 Hz, variation correction below 25 pF
ANALOG STEREO INPUTS
2 XLR (20K), 2 RCA line, one switchable to phono
DIGITAL INPUTS
2 XLR AES/EBU (110 ohms), 2 RCA S/PDIF (75 ohms), 2 Optic Toslink S/PDIF, 1 BNC Word Clock
ANALOG STEREO OUTPUTS
2 XLR, 2 RCA
DIGITAL OUTPUTS
2 XLR AES/EBU (110 ohms), 2 RCA S/PDIF (75 ohms), 1 BNC Word Clock
OUTPUT CONFIGURATIONS
Stereo, double stereo, bi-amplification, 2.1, 2.2, 3.0 or LCR (left, right and center), 3.1, LCRS (left, right, center and surround) and quadraphonic
UPnP/DLNA-compatible network input (Ethernet and WiFi)
INTERNAL PROCESSOR
Intel Duo-Core 1.8 GHz, 64-bit floating-point computing, 1 GB DDR3 hard disk, cooling (computer part) via heatsink and fanManufacturer’s we
