Putting a ding in fun. Again, hifi advances like the miniaturization of existing tech, novel production methods, new parts, performance increases etc rely on research and development. R&D funding for the military, medical, industrial and IT sectors massively trounces what even the largest audio conglomerates can allocate. What to say of small boutique firms? Hifi electronics rely on opamps, FPGA/DAC chips and transistors developed for these busier sectors to benefit from ongoing advances outside our small cottage industry which can't afford to finance them.

Meanwhile high-end drive units are limited to mostly hifi speakers. Pro and sound reinforcement units are for concert venues, clubs, churches and public address systems. As high-volume special-application parts, the automotive industry has its own catalogues and key suppliers. As we learnt from a recent KR Audio announcement, about a range of new tubes financed by big order commitments from LampizatOr and a UK-based e-commerce vendor, parts manufacturers can fund improvements with sizeable orders. Those of course tend to be very unlikely to come from new small companies whose operating capital is generated exclusively by sales. In their case, true custom orders—substantially more than just minor modifications to stock parts—only come after many years of successful business. Neither Jim Thiel nor Richard Vandersteen started out using their own drivers.

Æquo Audio did from day one. Already their first product sported ground-up drivers not found elsewhere. The Ensis midrange which Stilla inherited [above] combines a mineral-loaded self-damped polypropylene cone with an Accuton-style very fast symmetrical motor system. Like Ensis, this central driver is only low-passed on top with a 6dB/1st-order filter at ~2'000Hz. The lower roll-off mirroring the woofers which enter with a 2nd-order/100Hz low-pass is purely mechanical. This avoids the usual 3-way's midrange high-pass. Stilla is really more of a 2-way plus precision-matched active sub in one svelte cabinet. About the bass system which uses purely analog compensation to measurably mimic the behaviour of closed-box loading, Ivo explained that "Stilla wouldn't have been possible with the woofer tech of just 5 years ago." Their 7-inchers benefit from the latest advances of mating a long-throw cone to an ultra-fast motor system. Æquo's new soft-dome tweeter for Stilla sports the same optimized airflow magnetics of the Ensis tweeter, then raises acoustic lens efficiency which broadens lateral dispersion whilst limiting floor and ceiling reflections*. To fully control their cabinetry, production of thermo-formed synthetic stone was already in-house for Ensis yet developed further for Stilla. It starts with sourcing sheets of raw material whose thermal specs and tolerances exceed Corian and Hi-Macs and which contains 70% ceramics. It heats them at just the right temperature before a 20-ton press bends them into the desired shapes in precision moulds. This process R&D and related industrial equipment relied on the two principals' savings from previous jobs before the first Ensis ever sold. Later another smaller round of funding involved all team members and some of their families. This maintains 100% in-house ownership to prevent putting any ding in funding.

* This is 90° different from 8mmaudio's far deeper very narrow tweeter waveguide whose designer aimed at restricting lateral dispersion for fewer sidewall reflections, preferring instead to widen dispersion in the vertical plane between floor and ceiling. Where Æquo's ovoid waveguide orients sideways, 8mm's does it upright.

Relative to driver research, Æquo maintain a very substantial database of not only units they've bought and tested but of individual suppliers they've identified from whom various major driver design houses source their specific materials. This allows Ivo to strategically specify what exactly he wants for each of his transducers. Such detailed knowledge makes him an unusually active collaborator with his chosen driver manufacturers.

Relative to cabinet design, Ivo is adamant about time alignment to support a flawless step response. Much development time is spent also on resonance optimization. This led to research into the optimal thickness of the Ply and synthetic stone skins of Stilla's 'boat hull' and specialty glues which bond them to double as constrained-layer damping compound.

For Stilla, high-power music testing past the original plinth design of aluminium with synthetic stone inlay led to a revision. This increased the plinth's mass via added thickness to make this structure even more effective at sinking remaining front/aft cabinet resonances to ground - vital for clarity under stress like massive symphonic music at high SPL. No matter what aspects of Stilla's design I inquired about, Ivo had very detailed lengthy explanations about their respective why/how to demonstrate an unusually comprehensive approach to speaker design. Much effort was spent to reduce this speaker's physical dimensions yet guarantee full-range performance without typical compromises.

Those perfectly happy having big imposing speakers dominate their living space won't appreciate that aspect of Æquo's efforts. In fact, they may write off Stilla precisely because of her petite figure. That's not the target audience. The target audience are those who want big high-end sound in a compact package and not add a third or forth box called a subwoofer or two. They get that physical miniaturization without sonic shrinkage is a rather costlier proposition than inconsiderate design laziness which advocates grotesque sizes; plus one which categorically relies on active bass. Those who suffer conceptual issues with self-powered bass systems or class D for sub 100Hz coverage won't be compadre with Æquo's current approach. They will have to wait for their forthcoming €10'000/pr passive Gladium. Work on Stilla and Gladium plus associated dealer feedback influenced ongoing design work on the Diluvium flagship which stepped away from the earlier über Ensis concept for a more streamlined appearance.

"The 3-way Gladium will get a smaller Stilla-derived EHDL tweeter with motor speed between Ensis and Stilla whilst its size benefits from excellent top octave dispersion to work well with the larger tilt of the cabinet. The new larger waveguide optimized for the speaker's specific characteristics helps to still use a low crossover point of around 2'500Hz and maintain high sensitivity. The 5" midrange will be a hybrid of Ensis/Stilla midrange and Stilla subwoofer tech. It will employ a meta-aramid coated paper-pulp cone and special magnet design for a symmetric force field like the Stilla subs now optimized with voice-coil properties to result in transient speed of the same extreme high level as the Stilla and Ensis midrange without the need for a more expensive fully symmetric motor layout. The 10" aluminium-cone woofer will be virtually identical to the Ensis subwoofer, equal in dynamics, cleanliness and resolution yet optimized for a larger bass reflex cabinet to result in less hunger for power than the active Ensis version. The front horn-loaded port will be similar to Stilla and also tuned as low as 20Hz to work in the pressure not time domain for delay-free bass. Perfect time and phase alignment between drivers with low-order filters will be similar to Ensis and Stilla. Gladium will be a 4Ω nominal design with 89dB sensitivity suitable for a wide range of amplifiers, offering >115dB dynamic range for each speaker when driven by high-power amps. The 118x42x29cm enclosure will be made from high-density compressed fiber wood with double 30mm baffle, one for the mid/HF drivers, a separate deeper baffle for the woofer. The resonant-free side panels will be made by hydraulic pressure forming of multiple Ply and acrylic layers and styled as inspired by the Diluvium flagship."

Gladium and Diluvium.

"The 126cm tall Diluvium will get our EHD tweeter system fitted with a new neodymium fully symmetrical motor for transient response that's faster than virtually any moving-coil transducer currently used, surpassing the resolution of even most ribbons while having the benefit of large bandwidth and optimal vertical vs horizontal dispersion. The 5" midrange will become a further development of the Ensis/Stilla midrange, employing a comparable fully symmetrical motor with a voice coil optimized for midrange frequencies for even faster transient response. The special mineral-filled cone is further reduced in self resonance and has a dust cap design for less compression effects in the voice-coil cavity. The rubber surround's shape is optimized specifically for the midrange to eliminate energy storage and diffraction. The cabinet is a special new topology to be disclosed later. An 8" upper-bass aluminium cone driver in a closed cavity will be a further development of the Ensis, now curved for higher stiffness vs weight plus high self damping to push remaining break-up modes to 5-10kHz. Coupled to a high-resolution fully symmetric drive motor and suspension, it delivers Klippel-confirmed linearity of over 18mm p-p. It slams with amazing cleanliness, with 3rd-order harmonics below 0.05% and 5th-order below 0.01% in the 100-500Hz band even far beyond normal listening levels.


"The subwoofer section consists of all new drivers in a sealed loading which offer the newest and best technology currently available for all desired performance characteristics: latest-gen full symmetric drive for transient response times in excess of most current midrange drivers while maintaining high excursion linearity and peak linearity in excess of the Ensis subwoofer. The upper/lower subwoofers have respectively 11" and 13" coated sandwich-foamed paper-pulp cones for very high stiffness vs high wideband damning. These new drivers each can take long-term continuous power of more than twice the Ensis subwoofer. All three bass drivers will be powered by individual Arpec controls in a system of NC1200-based nCore amplifiers with much higher currents made available to the woofers. Not just the sub bass will be adjustable like Ensis but also the degree of bass kick to match the character of whatever amp is used on the passive midrange and tweeter. Furthermore, the speaker will get adjustable presence energy controls to fit a room's level of absorptive surfaces while it actively cancels out early reflections in the mid region from side walls, floor and ceiling. Finally, Diluvium will have all the necessary easy mechanical adjustments for perfect time alignment of all drivers down to the millimetre. Sensitivity will be >93dB and load behaviour super easy to suit high-end low-power SET and class A transistors."

Back to Stilla, on raw specs
we get dimensions of 107x16x26cm HxWxD with a weight of 20kg/ea. 2.83V sensitivity is 90dB and claimed bandwidth 18Hz-35'000Hz. Impedance is a nominal 8Ω to "make her compatible with a wide range of excellent-sounding amplifiers of lesser power". The materials palette is synthetic stone, Scandinavian Plywood, HDF, billet aluminium and high-density sheep's wool. The connectors are WBT binding posts for the speaker cable and SpeakOn for the 3-metre power cord. The analog adjustments on top of the speaker are for room size [XXS to XXL] and placement [boundary compensation). The manual adjustment is for the cabinet tilt via single wheel. The standard finish is matte white. High-gloss black and various wood veneers occupy the first surcharge tier, custom RAL colours the second. Shipment is via shared single 50kg box, another nod at compact sizing and relatively low mass per speaker.

Stilla tweeter, midrange and one of two woofers inside the enclosure.