Review sample supplied by hexagonaudio
Manufacturer: Stentor SAS – Apertura
Retail prices in the NL (incl 21% VAT):
Armonia Evolution – €6.500
Edena Evolution – €9.500
Adamante – €18.000
Three Models Compared
In this review, I will compare three models from the current Apertura lineup to provide a representative cross-section of their performance and illustrate what to expect when moving up the ladder. The Armonia Evolution is the smallest model with a ribbon tweeter. The Edena Evolution is similar, but larger in construction. It uses the same ribbon tweeter with a larger woofer. The Adamante is the biggest and most upscale model under the Flagship Engima MkII. It has two woofers and a larger ribbon tweeter, in a D’Appolito configuration.
Apertura in a nutshell
The story starts with Christian Yvon and his passion for sound reproduction.
In 1978, Christian Yvon created his own laboratory to lead sound and acoustic research; he has developed several new technologies while striving to reproduce the recorded musical information as faithfully as possible, not more, not less; the proprietary DRIM crossover structure is one of them.
In 1979, he worked for Goldmund speakers and developed many of their products, such as the “Dialogue,” “Apologue,” “Analogue,” and “Epilogue” loudspeakers. Christian Yvon also worked for Focal, Sonus Faber, and many others.
In 1982, he decided to develop his own loudspeakers, choosing the name Apertura as the brand and going on to develop a full range of loudspeakers over the decades.
In 2010, Christian Yvon met Eric Poyer. Eric Poyer had extensive experience at a renowned high-end manufacturer before founding his own OEM audio company over 20 years ago. Christian and Eric partnered and created the company “Stentor” to develop and produce a complete line of Apertura products. For the last 16 years, this collaboration has resulted in the development of a comprehensive product range.
Stentor SAS – Apertura is a family business company where the whole team is 100% committed to building the perfect loudspeaker. As a part of this team, Christian is in charge of acoustic design, and Eric is responsible for mechanical design and production. Apertura loudspeakers are handcrafted in France at the head office near Nantes on the West Coast, in close collaboration with a small number of tightly selected subcontractors. Cabinets and drive units are rigorously selected from the best, and every manufacturing step is performed internally to build a high-end product, including acoustic and mechanical design, drive unit testing and matching, crossover design and manufacture, assembly, and individual strict tests before packing.
Technologies common to all three models
> Low Storage Cabinet with curved walls: not flat, machined panels
The curved walls and asymmetrical shape of the Apertura cabinets go beyond aesthetics. Instead of typical MDF, their construction uses multiple thin HDF layers bonded and molded under pressure, making them stiffer and better at dissipating energy than solid slabs. This raises the resonant frequency and prevents resonance at a single frequency. The cabinet’s low-storage signature helps minimize intermodulation distortion, which can blur and obscure the mid-range or create uneven, one-note bass sounds. Combined with an asymmetrical footprint, internal bracing, double-thickness panels in key locations, and lap joints instead of butt joints, this results in a cabinet with diffuse resonance, excellent energy dissipation, and minimal coloration.
> Asymmetry And The Internal Air Volume: Attenuation of internal energy through clever choice of materials and cabinet design
Many believe that asymmetrical cabinet walls prevent standing waves, but Apertura believes that’s a misnomer. Curved walls mainly add stiffness and resist flexure; they do not control internal standing waves. Controlling internal energy is essential for sound clarity, as drive units project energy backward that can cause resonances and leakage. Effective solutions involve more than just adding absorptive wadding; they require a multi-faceted approach. Apertura uses calculated damping materials, including proprietary pocketed sheeting, to influence airflow and reduce unwanted vibrations. The rear panel area is also minimized, while the top and bottom panels are double-thickness to prevent driver rear energy from disrupting the sound.
> Mechanical Grounding: One spike, not three and definitely not four
The unwanted pressure from the driver’s rear wave can cause many issues, such as vibrating the cabinet and feeding energy back into the drivers, thereby distorting the sound. However, simply absorbing this energy creates problems. The cabinet’s main role is to load drivers and contain rear output, but once energy enters, it moves problems elsewhere. The ideal is a clean exit path into the supporting surface, like proper grounding. Often, speakers rest on spikes, but these are often misused, creating multiple, confusing paths that disrupt stability. Apertura uses a single ground path at the speaker’s center, with adjustable round-tipped outriggers for precise alignment.
> The DRIM Crossover: Simplicity and phase coherence, as well as steep slopes
According to Apertura, the crossover is the weakest point in any loudspeaker design, often harming signal phase and timing. Christian Yvon’s DRIM crossover topology, unique to his designs, achieves phase coherence crucial for musical reproduction with steep slopes to eliminate out-of-band driver artifacts. Simple, low-order crossovers have good phase coherence but roll off slowly, allowing breakup modes and peaks to form. The DRIM crossover combines phase coherence with steep, adjustable slopes for precise driver matching. Apertura speakers use this approach with two-way designs for simplicity and musicality, and adaptable slopes to accommodate wideband ribbon drivers. Drivers are measured, matched, and the crossover tuned for each pair, resulting in excellent driver integration, consistency, and system performance at this price.
Armonia Evolution
The Armonia Evolution is the smallest Apertura loudspeaker model to feature a ribbon tweeter. This newest tweeter model features a flat, metalized polymer diaphragm that is twice as large as the one on the non-Evo Armonia tweeter. The double surface area reduces the ribbon’s movement, thereby lowering distortion. The tweeter is paired with an 18 cm “isotactic matrix” mid/woofer with a woven polypropylene composite cone and a long voice coil for a high linear excursion. The isotactic matrix material combines stiffness, lightness, and good damping properties. The speaker has an amplifier-friendly nominal 8-Ohm impedance with a moderate 87dB efficiency.
The Armonia Evo’s proprietary DRIM crossover design features triple attenuation slopes and phase control throughout the entire bandwidth. The Armonia Evolution crossover uses two separate circuit boards for the low-pass and high-pass sections and incorporates very high-end capacitors. Each set of drive units is individually measured, with crossover parameters adjusted accordingly. Hand wiring is performed on a 140 µm copper printed circuit board. The crossover structure is optimized to prevent magnetic interference between components, and the pure copper terminal block is silver-plated.
The cabinet features a unique shape with two curved sides of varying lengths and no parallel front and back panels. It consists of a laminar, pressure-molded structure made from thin layers designed to absorb vibrations and prevent the transmission of vibrational modes. Inside, a multi-cavity framework adds stiffness and provides designated spots for damping materials to eliminate standing waves, utilizing three different types of damping materials.
Instead of the usual 3 or 4 spikes, the Armonia Evolution is mechanically grounded using a 5-footer system. To optimize the dispersal of structure-borne noise into the floor, the speaker enclosure rests primarily on a central cone positioned at the center of gravity, along with four adjustable outriggers for precise alignment. Aluminum stands and spikes are included: silver anodized for the High Gloss White finish and black anodized for all other finishes.
Armonia Evolution specifications:
Six different standard finishes are available:
Satin: Light Oak, American Walnut
High Gloss: Figured Maple, Rosewood, Piano Black, White
Frequency range: 37Hz – 30kHz +-3dB
Sensitivity: 87dB/2.83v/1m
Impedance: 8Ω
Load: bass-reflex
Drive units: 18 cm mid-woofer, 8×120 mm ribbon tweeter
Crossover frequency: 2,8 kHz
Dimensions with stands: 292 x 291 x 1069 mm (W x D x H)
Weight: 22,2kg
