Technologies developed by Aequo Audio
Nanotech Materials for Next-Level Acoustics
Speaker cabinets made from a Metal Matrix Composite enhanced with special Nanotube/Graphene assemblies, twice as stiff as aluminium, with 10 times better damping, free from any resonance from 1hz to >100.000hz (!) and excellent thermal conductance (Nanocast-MMC). If needed, enhanced with pre-tensioned artificial stone optimised for stiffness and damping. Or, an ultra-light Polymer Matrix Composite version; the ultimate solution for non-fatiguing and non-ringing driver membranes (Nanocast-PMC). These are a few fruits of the extensive research done by Aequo Audio in the material sciences. (more information about these exotic acoustic materials on www.diluvite.com)
Pure Analogue Active Bass (No DSP involved)
A fully analogue active bass system for the first hybrid speakers with all the benefits from active bass, without any drawbacks: deep natural extension, perfect coherency and point-source sound reproduction. Fast and large-scale slam, always taut and well- controlled, without delays and without D/A conversion. The full bandwidth output of the connected power amp is used, leaving its full character intact over all frequencies, but relieving it from the duty of driving difficult loads in the bass region. This makes amplifier matching easy and allowing better sound than ever before, without the need to turn to beefier and bigger amps at higher price tags. For the engineers at Aequo a logical solution to increase bang for buck in any system budget and forever solve the passive vs active dilemma, yet it's smart implementation remains to be a unique feature in today's high-end audio landscape.
ARPEC™ – Analogue Room Adjustment
Active bass controlled by the analogue ARPEC™ system, enables very easy and intuitive room and placement adjustments, controlled by two stepless rotators placed on each individual loudspeaker. One rotator for room size, varying from XXS to M to XXL, the other for speaker placement, varying from standing in a corner to a position completely free of walls. Speakers are easier to place and get perfectly balanced, without the risk of any unnatural artefacts, or loss of coherency in soundstage, pace or timing. Easy, speaker-matching and safe, delivering that perfect balance in any room.
Acoustic Driver Design
The engineers of Aequo Audio understand optimal driver design and carefully choose the best materials and dimensions, electro-mechanical parameters, and specific and optimal driver parts best suited for the performing role of each transducer. Engineered and assembled in collaboration with the world’s best driver manufacturing specialists from Denmark such as Per Skaaning, son of the legendary Ejvind Skaaning, founder of Scanspeak and Dynaudio and responsible for many leaps in audio driver science.
EHDL™ High Frequency System
Based on extensive research of the relation of energy dispersion by all types possible tweeter systems and optimal sound performance, the EHDL system combines low distortion moving coil tweeters with a controlled vertical/horizontal dispersion lens for the ultimate holographic 3D soundstage and superb imaging. It solves the problems of top octave response irregularities as well as fixes the non-pistonic drawbacks normally encountered by soft dome tweeters without introducing the harshness of hard domes.
Focus on R&D with in-house facilities
By investing in own machinery, working closely with local high-tech Brainport facilities and especially the Technical University of Eindhoven, Aequo Audio can develop all technologies in-house, allowing great understanding in several fields and sciences. New talents on the University are directly spotted and taken aboard the R&D team to ensure its technological advantage in certain areas and expand to others when possible, also ensuring future cutting-edge technologies to be spotted at an early stage.
High-tech roots: Brainport Eindhoven
When Gerard Philips started a light Bulb factory in Eindhoven in 1891, the industrial revolution in the Netherlands had only just begun. As he was always very interested in new technologies, he founded NatLab, a physics research facility. Mr. Philips could not know then how this was probably the start of what now is one of Europe’s most important High Tech regions: Brainport. The days of Philips as a multidisciplinary tech company with 412.000 employees in
1974 are long gone. Yet Gerard’s spirit of innovation through research and technology is still very much alive. The region is now known for Philips spin offs as ASML, responsible for over 80% over the world’s chipmaking machines. And what about NatLab? Its successor High Tech Campus is the smartest square mile of the world, with over 10.000 researches, developers and entrepreneurs. The heart of Brainport.
You might understand that the fact Aequo Audio is originated in Eindhoven, is no coincidence. The designers and engineers of Aequo Audio believe in the credo of the region where they were raised: innovation trough collaboration, research and technology. At the same time, the location of the Netherlands between Germany, England, France and Denmark feels as being in the middle of Europe’s most important audio
developments and speaker brands. Still, Aequo Audio likes to do things a bit differently. Right here on this page, you can read about the most important technologies used or developed by Aequo Audio. You will learn about the truly unique and complete composition of new, state of the art technology, for exceptional next level performance in high-end loudspeakers.
- Detailed description of innovations and technologies developed by Aequo Audio Laboratories -
Aequo Audio Whitepapers
Nanotech Materials for Next-Level Acoustics
Nanotech Materials for Next-Level Acoustics
Since the arrival of nanotechnology in the 1980’s, large leaps in the performance of composites have been made possible by applying technologies on the scale of nanometres and micrometres used in fields such as surface science, chemistry, biology, energy and medicine. In micro fabrication or molecular engineering, a lot of break troughs have been reported on what’s possible with organic (carbon) and ceramic based composites. The more famous ones are certainly Carbon Nano Tubes (CNT) and graphene: the building sheet itself used for CNT’s but now as a single layer of hexagonal bonded carbon molecules.
Some variants of these materials have become less expensive and have found their way in industrial engineering and even some consumer product designs. Furthermore, scalable and affordable Nano- and micro-tubes made of ceramic or even inorganic natural materials have been discovered, enabling even more possibilities for both designers as well as manufacturing improvements. The bottom line is that extreme properties previously not possible on a macro scale are now made possible by rearranging the same basic molecules on a Nano scale.
Promising properties on paper do not always result in good performance. Many applications of CNT’s are disappointing in performance and especially when considering cost vs performance. Most problems are linked to lacking production processes and dispersion problems. Also, using commercially available CNT’s in a matrix composite, regardless if single walled (SWCNT), double walled (DWCNT) and multi-walled (MWCNT) and even when properly dispersed, will always trade in gained stiffness against poorer damping.
Unfortunately, some issues also apply to graphene. It may have on paper the single highest stiffness value however -when applied as a coating- this does not help stiffness performance much for the gained stiffness: such a thin layer (0,334 nanometre) is usually insignificant for the design’s performance. Also, the boosted high paper-value applies for the in-plane direction of the platelet only, hence the actual improvement when structuring it as a nanotube (CNT). Multiple layers will fail to help as these hexagonal layers do not bond and can freely slide over each other ((only under 10 layers is considered graphene (transparent), above is exfoliated graphite (grey).
The Nanotech Composites that Aequo Audio have developed, are perhaps today’s best and most versatile example of what can be made possible and put in actual and real delivered performance, when searching for solutions that were previously compromised by opposing properties (stiffness and damping) as encountered while evaluating purely macro-engineered materials, or as compromised by measured performance of many bad applied common Nano materials. Furthermore, the presented product portfolio provides for excellent thermal solutions and is offered against best performance/cost value in the nanotech industry.
More on the big battle: Stiffness versus Damping
These are the two properties desired when fighting off unwanted vibrations that cause side effects such as distorted (audio) signals and panel vibrations. Unwanted resonances are some of the most overlooked or hard to overcome factors that cause wear and failure of components such as in metalworking and other industries or make the difference between winning a motorsports race and losing it (for either engine failure or decided compromised performance in order to prevent such failure of current used materials). Stiffness helps to take on force without bending/deforming (Young’s modulus, storage modulus) while damping helps to lose energy by dissipation (loss factor tan). Stiffer unfortunately means almost always lower damping, that’s the big battle.
Some metals such as some aluminium alloys, steels, titanium and beryllium (a lightweight and stiff metal that is both expensive and toxic) can excel in stiffness but perform poorly in damping. Some pure metals have good damping properties, such as magnesium, but will lose those properties when alloyed to make it usable and strong enough for manufacturing.
Extremely stiff carbon ply epoxy laminates and ceramics can even provide double or triple the stiffness of metals, but fail in the loss of energy when made to resonate, as well as the laminating procedure of the carbon ply limits design freedom and increases labour costs. Diamond may lead in hardness but again: poor damping - now combined with high costs - limit practical application. For the reasons mentioned here, both synthetic diamond and beryllium are starting to disappoint as the promised solution in high-end loudspeaker driver membranes as they do raise odd harmonics at the cost of lowering even harmonic distortion at the lower end of the usable frequency bandwidth.
Furthermore, most of the resin based and ceramic super stiff solutions offer poor thermal properties. The Nanotech materials created by Aequo Audio are now commercially available under the name of D I L U V I T E™ Nanotech Composites. D I L U V I T E™ Nanotech Composites offer custom solutions for virtual any application in need of both stiffness and damping, using assemblies of ultra-stiff and ultra-high damping materials and applied coatings, but perhaps even more exceptional: as a standalone casted matrix composite were high stiffness goes already hand in hand with high damping, as made possible by special carriers enhanced with carefully selected and structured nanotech ingredients. Those seeking best performance and thicker walled components can choose NANOCAST-MMC™ where those wanting low density and thin-wall solutions go for NANOCAST-PMC™. In either way they will take a leap in engineered performance that allows getting a big step ahead in their game and playing field, and ultimately winning the battle.
Preliminary product data and comparison to a variety of materials
Below you find a comparison of materials with properties listed as:
Stiffness Young’s Modulus E in Gpa (measured, averaged or range)
Damping loss Damping loss in factor N
Loss Modulus Performance for combination of stiffness x damping
Conductivity Thermal conductivity
Cost In 1-7* signs depending on complete applied cost relative to alternatives
As earlier mentioned, these next-level acoustic nano-materials are now commercially available under the name of D I L U V I T E™ Nanotech Composites. Applications of these materials can be used in high-end audio, aerospace, tribology, automotive or other fields where better vibrational control is needed.
You can find more information about these exotic acoustic materials on www.diluvite.com.
Pure Analogue Active Bass (No DSP)
Pure Analogue Active Bass (No DSP)
In the world of custom installations and full active studio or other PA systems, the introduction of Digital Signal Processing (DSP) soon became a widely used tool to extend low frequency production, do specific room adjustments and even replace passive crossover filters. Additionally, there has been a trend towards consumer-friendly DSP systems for room correction: automatically through measurement with a microphone by the user of DSP equipped AV receivers or standalone room adjustment systems, and even by self-measuring active speakers. All these systems, both professional and of the universal consumer type as well as self-measuring electronics and speakers, are not without flaws.
An overview of these DSP flaws:
In case of universal DSP for low frequency extension and room adjustment, there is a big risk of pushing low frequency transducers or the associated amplifier channels over their limits if the speakers, subwoofers or associated amplifiers were not specifically designed for these conditions. This will result in very audible distortion in the lowest octaves at all listening levels, or even permanent damage of either amplifier or low frequency driver at higher listening levels (thermally, mechanically or trough clipping). Bass reflex speakers and subwoofers are specifically tuned by the manufacturer and especially vulnerable to such damage.
These systems often rely on one or just a small series of measurements from the listening position(s), and most self-measuring speakers will not even measure from such a position. Even with large amounts of measurements, automatic DSP correction systems can produce peaky EQ and Phase adjustments resulting in removing one problem by adding another (absence in certain frequencies in one place and adding too much in another, or moving problems to a different frequency range). They also introduce audible problems in the time-domain by small-band group delays.
Even professionally adjusted DSP systems by qualified sound engineers can sound slow, strange or just plain dull and lifeless.
In case of DSP added solely to the subwoofer section, the DSP itself will always need computing time by its processor for adjustment, dithering and A/D and D/A conversions, causing a delay to the rest of the system.
Although phase corrections can partly solve this, your lows will always run wavelengths behind the rest as you cannot shift phase back in time.
Increasingly popular Hybrid active/passive speakers using integrated DSP will have delay solely on the lows and will therefore also suffer from the same problem and not reach the uniformity as one may and should expect in high-end audio. A properly aligned speaker actually plays as one speaker instead of separate drivers to allow you to pinpoint the double bass or bass guitar in your soundstage without blur or fussiness.
DSP platforms used for the active filtering of midrange and high frequency transducers are virtually always limited in their use of combined ideal response curves combined with precise wideband phase alignment when compared to passive filters of the best quality, as used in both the Ensis and Stilla, and the best sounding price-no-object top high end loudspeakers.
The bitrate of the best and newest DSP’s A/D and D/A will always be behind on the latest sound formats. It was at cd quality when there was SACD, at 96/24 when there was 192/24 and at 192/24 while we are at even higher bitrate DSD. In case of DSD, you probably lose the benefits of the format, without regards to bitrate.
Even if you find the bitrate and source format-compatibility of your DSP sufficient, adding another conversion from analogue to digital and back can be a sacrifice for you.
Audiophiles with totally analogue systems will keep away (far!) from any device implementing A/D in their gear, and with good reasons as it would make their beloved vinyl or other analogue source and signal path meaningless and futile.
Although Aequo Audio has used DSP in the past and still sees a role for DSP in very specific goals in the future, in this case the analogue system is far more superior. Active bass also allow a larger amount of amplifiers that can be matched.
In our desire to make speakers produced in-series that could enhance the musicality for a large group of potential customers using a range of amplification, Aequo Audio soon discovered there were many amplifiers that would in general either:
Lack power (outside specified power)
Lack control (sometimes outside listed dampening factor)
Sound too analytical or bright
Sound too warm and fuzzy
To overcome these issues, the amplifiers had to be endlessly tried to work best with other components in the system, especially the speakers. It often results in a compromised choice between musicality and aspects like grip and cleanliness. Even despite ultimately finding the best possible value in the best possible match, it often still asks for a big overall budget for the system as a whole.
We learned that for some of the potentially most musical sounding amplifiers, the frequency bands, where most is asked of the power amp modules and power supplies, could harmfully affect other frequency bands and overall performance in all aspects. By incorporating our hybrid designs, using active powered bass drivers, we could solve many of these issues and make connected amplifiers sound much better than they ever did before. Additionally we made the moving parts of the passive mid/high section extremely light and with incredibly effective motors, so that we can offer speakers with respectively 93db, 90db at 8 ohms nominal (ie. 96 and 93db at 4 ohms nominal, near horn speaker performance) for the Diluvium prototype and Ensis speaker. For the Stilla we wanted to match the Ensis sensitivity and 8 ohm nominal workload to work with virtually any amplifier considering power output, impedance and damping factors, to provide listeners with better performance versus value in their system of choice.
With regards to the tonality, timbre and overall musical character of the amplifier, the combination of highly controlling, fast precision motors, on well self-dampened cone/dome moving membranes, brings out the best in over-forgiving or slower amplifiers, as well as the more analytical equipment. The Stilla does not put any emphasis on clinical sound by resonance of hard materials on such amplifiers, while always delivering musicality, impressive detail and air.
ARPEC™ – Analogue Room Adjustment
ARPEC™ – Analogue Room Adjustment
The Ensis and Stilla models have been equipped with one of the most bespoken new technologies developed in-house by Aequo Audio: ARPEC™. Aequo Audio studies the effects of room size and speaker placement and implements this knowledge in this piece of high-tech yet fully analogue hardware. It controls the low frequency extension of the integrated active subwoofer to fit the “room gain” of any room from small to large. And it properly adjusts the bass levels to correspond with speaker placement in room corners as well as that of a positioning near a wall or in the open field, and everything in between.
ARPEC™ ensures a deep and natural roll off into the lowest notes and does so with a full analogue signal path and phase alignment to the midbass driver in the speaker. It avoids the unnatural notches usually made by DSP controlled systems, accompanied by slow or sterile sound, even if made of multiple measurement positions. Just use the two easy and steples adjusted rotators to find the perfect match without any hassle. A real first and original analogue room adjustment system that gets the job done. And so the compact yet very capable Aequo Audio speaker models with ARPEC™ become a high-end speaker truly unique in its versatility for any room or placement in the real world.
Many tower speakers today have multiple small bass drivers instead of proper subwoofers. Sometimes few, sometimes many of them aligned in the tower itself or even in a separate tower. Nonmatter the number of them and the total moving surface in result, they fail to provide the cleanliness and reproductive authority you want below 50hz. And they usually rely on bassreflex ports that can sound slow or boomy when interacting with the room. Speakers in the top class need drivers specifically built for performance in this area. To have the Ensis model deliver such cleanliness, its cabinet has a clever and original shape like that of a musical note. It allows the placement of a 10 inch subwoofer. Viewed three-dimensionally the special cabinet has also the benefit of facing the subwoofer somewhat forward, to keep the subwoofer from facing the rear wall if the speakers are positioned with some toe-in for best neutrality and imaging. The Stilla model has two long linear throw 7-inch subwoofers hidden inside the enclosure, placed in a 45 degree angle to cancel out sideway vibrations.
To handle the carefully thought-trough adjustment control of the ARPEC™ system and deliver the best possible lows in general, the 10inch subwoofer driver of the Ensis has been equipped with exceptional qualities. The large heat resistant voice coil of 34mm long is placed between a 8mm magnet gap in an overhung double magnet system with an exceptional large force field outside the gap to bring the linear motor travel to an incredible 50mm. Long voice coils can lead to slow signal response, but not so in the Ensis subwoofer. A clever symmetric motor design with rings and pole extenders introduce a very fast signal response comparable to most smaller drivers used above subwoofer frequencies.
The mechanical design couples this high precision motor to a very reliable Nomex spider and a large yet flexible rubber surround. The end result has been reviewed with the world’s best driver measurement equipment from Klippel Germany to prove a linear travel of 25mm of the total system surpassing any other 10-inch subwoofer of such fast signal response.
Ventilation of the motor under the dust cap and the low loss suspension guarantee very low compression effects for an open and natural playback of dynamic passages in your music collection. The driven cone is made of lightweight and very rigid aluminium, black anodized for optimal heat dissipation, to handle the force with ultra-low distortion when both used very delicately or very brute. The room and placement adjustable lows of both Ensis and Stilla have incredible dynamic drive, are superfast and taut, are clean, natural and open, and go impressively deep.
When the Ensis speaker was developed Aequo Audio was cognizant of the benefits of the fully analogue ARPEC™ system on compact closed box speakers. We made it get rid of unwanted behaviour from a big capable subwoofer driver in a very small enclosure, delivering the ultimate desirable roll-off regardless of cabinet size. It could also be used to tune this roll-off for different sized rooms along with placement near walls or corners as well as the ability to make individual speaker adjustments to overcome any asymmetry of the listening room’s layout near the speakers. And all of that without the time delay, for computing time of the processor, or A/D losses inflicted by DSP solutions.
To meet the demands for the low frequency dynamics of the Stilla speaker, we were able to use ARPEC™ in a very new way: to tune a ported speaker to have the same ideal behaviour. Using the knowledge collected of ideal roll offs in various rooms and for various placement options, we applied the theoretical capabilities of our in-house developed ARPEC™ hardware, to get a very similar result to closed box speakers but with gained efficiency by adding the output of a port.
The port on the Stilla speaker is front loaded to stay away from front-wall inflicted “boomy” bass, whilst tuned so low that it produces frequency waves that are too big to fit in most, even large, rooms. The output from the port therefore works in the pressure domain, instead of the phase-time domain. Further acoustical down-sides of normal ports, inflicted by the specific port roll off, were avoided in the audio band by mimicking a closed-box response. Finally, we angled the front port bass units to “roll” over the ground plane of the room towards the listener, extending the frequency band below 20hz whilst using a horn loaded tapered cavity over the total depth of the speaker thereby improving the aerodynamics of the port to eradicate compression effects and noise whilst also allowing the use of acoustic material for dampening any remaining scuffing or driver-motor sounds at excessive volume levels.
The double 7 inch subwoofers were Klippel-tested to prove how a smart, optimised finite element computer motor design with super linear control, a high quality Nomex paper cone and a low-loss super-linear excursion, could keep things effortless and clean up to extreme excursions, even excessing the linear 12,5mm one way excursion of the Ensis subwoofer driver. To get the most out of these incredible powerhouses, the total power of the active amps was designed to match that of the Ensis, never falling short even in the most extreme conditions. These drivers were also fully vibration balanced by the smart placement of the first driver under 45 degrees, facing front and sideways, and then aligning a second one under it, also under 45 degrees, but facing to the opposed side of the speaker. This alleviated any sideways vibration and only backwards/frontwards directed vibrations were left which were then finally also dealt with by the innovative foot of the Stilla.
Stilla loudspeaker model. Measured close range, low frequency output at different ARPEC™ settings, of combined subwoofers/port output, showing a closed-box like roll-off and no dynamic compression at high output.
Acoustic Driver Design
Acoustic Driver Design
A very special driver was born through a special cooperation with the Skaaning family business now led by Per Skaaning. Per’s father Ejvind Skaaning was the guiding force behind several loudspeaker companies in Denmark; among the most prominent are Scan-Speak and Dynaudio corporations, both founded by Mr. Skaaning, and the best ideas of him and his former engineering team members at all those different companies have found their ways into all the drivers now used by Aequo Audio. The synergy between Aequo Audio’s detailed specifications, and Skaaning’s superb materials and technologies led to various prototype combinations of motor designs both underhung and overhung, suspensions and cone configuration. Only when the best and ultimate measurement specs and musical sound qualities were met, the final midbass driver was ready to be used, first in the Ensis model and later in the Stilla.
It consists of a powerful symmetric motor design with very fast , tweeter-like, signal response as well as large dynamic capabilities. There is a Hexagonal winded voice coil to get a closer wind, coupled to a Kapton Aluminium former. Unlike Aluminium, Kapton is not influenced by Eddy currents in the magnetic gap and is therefore the material of choice for higher frequency resolution, but has the downside of having no “break” at higher excursions. To improve reliability and push the dynamic limits, Aequo Audio implements a Kapton-Aluminium hybrid former to have best of both worlds. The special blend PP cone has very good self-dampening behaviour and no break-up problems as encountered in aluminium or even worse: magnesium midbass or midrange drivers. The cone coupled to the motor is very light and the absence of a phase plug in the dust cap area maximizes the moving cone surface. This keeps the transducer in pace with the very high full range sensitivity (>90db!)of the Ensis speaker without having the need of a lower impedance than the now 8 ohms nominal voice coil. This ensures ideal matching possibilities to any amplifier, including low power tube amps.
The combination of this driver’s motor and cone is unbelievably accurate in reproduction of the signal. Not only fast, but also and very clean in the midrange with no sign of driver breakup ringing in higher frequencies. Its well-mannered behaviour is showed by the CSD Waterfall Graph below, made by an actual measurement of the assembled but still unfiltered driver. These highly desired capabilities make it very suitable for our preferred low order crossover slopes. The loudspeaker therefore maintains clear of the unwanted group delay effects that accompany the high order filters necessary with metal or ceramic cone drivers in the midrange area, spoiling the natural vividness of the soundstage and imaging. Aequo Audio keeps full control over midrange movement, precise and clean, also without the need of stiff suspensions or the need of thicker or unevenly shaped surrounds or the terrible choice of no surround at all. The free movement of the driver, as a result, means the elimination of compression effects associated with lack of flexible excursion in many midrange drivers. It adds no “fairy dust” like some hard domes and no warmness or over pronunciation of details. It ensures a genuine experience and long-time listening pleasure.
Aequo Audio gained extensive knowledge with regards to avoiding unclean, distorted sound that could negatively affect music reproduction. This includes knowledge of how all driver’s cones, suspension, basket, and motor design, can cause unwanted side effects at very low, normal and up to very high listening levels. The driver design of the Stilla employs the latest technology by Aequo Audio and its partners, to sound so free of noise and distortion up to (or down to) levels rarely seen in speakers.
But, we are also aware of the important balance between even and odd harmonics and their ideal sound levels at specific ranges in frequency, and even in specific relativity to various listening levels. The company’s products all carry a specific harmonic distortion signature in their musical reproduction that reveals a high level of subjective and emotional understanding of how to make the distinction between unwanted distortion and the welcomed resurrection of lost musical harmonics that were lost during the recording process.
Many insiders and outsiders of the loudspeaker business still focus on various speaker transducer characteristics to wrongfully explain differences in precision, resolution or “airiness” in the reproduction of detail. One of the usual suspects in these stories is the weight of moving parts whilst another is the material of choice for these parts. However, the weight of moving parts is mostly just important for sensitivity. Heavier means that more energy or watts, are needed to achieve the same acceleration of the movement. With regards to material choice, some materials that are extremely stiff, when used in midrange and high frequency drivers’ cones, can add ringing sounds that work for a spectacular first encounter of the speaker but end up causing an unrealistic and fatiguing experience. Countermeasures to alleviate these ringing distortions are present in many hard cone/dome midrange and high frequency drivers today but, these almost always include high order filters that without exception compromise the time domain and coherency of the speakers involved.
Aequo Audio’s knowledge of using superfast, controlling motor designs on stiffer materials in the bass-section and softer, good self-dampening cone/dome materials in the mid/high section, has been used in every product that we make. The Diluvium prototype has the highest possible measured and interpreted resolution in moving coil transducers known today, without the use of extremely stiff membrane materials. Even though well-behaved, by using well self-dampening cones, this enhanced resolution can be challenging with the listener noticing some recordings that are of a lesser quality. This is especially true for the 1000-6000 Hz region where ears/minds are most perceptible to such shortcomings and where it can distract from bringing the musical message to the listener.
In our product portfolio we offer different steps of resolution in differently priced products. The Diluvium prototype benchmarks ultimate resolution at all frequencies by using a four-way design, whilst the three-way Ensis takes a step from there towards overall smoothness, still standing out in detail above virtually any speaker in its segment. Although the Stilla takes another step back to be more forgiving by adding high frequency smoothness, it still offers a natural, airy and fast playback, not any less detailed than other speakers at this price point. Coupled to this, the Stilla has benefited from being equipped with one of the many tested motor prototypes of the Ensis tweeter, namely the one that has the best balance between overall smooth musicality and detailed transparency. Meanwhile, the highly precise midbass driver of the Ensis has been included into the
Stilla design unchanged, as the ear/mind will take less notice of the level of fault-analysis of some recordings in this frequency-band, whilst the use of a first order filter between mid and high frequencies ensures a problem-free crossover and overall coherency in wideband transparency.
EHDL™ High Frequency System
EHDL™ High Frequency System
Instead of focusing on an as flat as possible frequency response on-axis or for a specific angle to the speaker, Aequo Audio looks at the energy distribution/dispersion in all directions at any angle. Aequo Audio studied how this energy is reflected, or how it is absorbed. The speaker’s energy dispersion pattern must work together with the room to make sure the right amount of energy reaches the listener, even when that can be at different positions. It also has to work with the room to make sure everything goes well in the time domain: later arriving reflected sound can be filtered out by our brains, but not if it arrives too close behind the original sound.
The commonly seen, fully round acoustic lens or waveguide (left picture below), will help the speaker to have less problems with a small “sweet spot” and lack of general absorption by the room, and it will also widen the usable bandwidth of the tweeter. Often required to work at best, the speaker with waveguide should still be tilted back, to fire a bit more energy towards the further away ceiling compared to the floor.
Two Ensis speakers fitted with an ordinary round waveguide showing distribution of sound energy by the tweeter. Red areas are sound reflecting from side-wall, floor and ceiling.
The tweeters commonly used in these applications (dome, ring or cone) excels over vertical shaped ribbons/AMT in cleanliness versus size, but, in some more difficult rooms with hard floors, they can be surpassed by ribbon/AMT in one aspect especially: the holographic soundstage and imaging. This is due to the limited vertical dispersion of the ribbon/AMT. Especially hard reflecting floors are the most common cause of sound lacking in soundstage and imaging. With more energy going sideways instead of up and down, the three-dimensional soundstage is easier achievable. However, too much of this effect, also common for ribbon/AMT, will make it almost impossible to still enjoy the speaker at different listening heights, like while standing or moving around.
And there is more on tweeters and waveguides to be taken into consideration: soft domes have desirable dampening, but these domes can have also too severe “non-pistonic” behaviour. This can be as worse as the middle of the dome moving in the opposite direction while resonating. Furthermore, waveguides or lenses can suffer from uneven energy effects in the top octave because reflections of the sound waves here will resonate between its surfaces on opposite sides of the tweeter without a “phase plug” or dispersion cone to keep that from happening.
Back to the increased directivity of energy by a lens/waveguide/horn: too much of it can make sound a bit forward and compressed or even aggressive. In addition, there is the risk of taking too much away from the energy to the sides, sometimes resulting in a soundstage that lacks in width.
Aequo Audio made a tweeter system for the Ensis that has all the benefits of all worlds by getting a low distortion compact tweeter, into a controlled vertical/horizontal dispersion lens. And by doing so we automatically added the benefit of being able to place the vertically modestly sized tweeter closer to the midrange. Some designs only allow a good listening experience in the distant field because the drivers are too far apart however, EHDL™ equipped speakers sound great at virtually any distance. A dispersion cone was added to eliminate unwanted effects in the top octave, and also used to fix the middle of the dome tweeter section against resonance.
For the Stilla specifically, the acoustic lens was optimised by using fast 3D prototyping to make it work with even more demanding (smaller) rooms and to adjust time alignment of the slightly less tall speaker to best fit the various possible listening heights. Easy tilt adjustments completes all needed for the best stage in virtually any room.
With the Ensis renowned for its coherency, Aequo Audio was keen to duplicate this experience in the Stilla. Equipping a speaker with EHDL™ helps to potentially seamlessly integrate tweeter and mid frequency bands. However, it is the crossover filter that can still make or break the coherency. The importance of phase aligning and the minimum phase-shift only possible with acoustical first-order crossover filters, as is appreciated by enthusiasts and audiophiles alike, were all applied into the design of the Stilla.
The crossover filter performance and the components used were on a par with the Ensis and other premium speakers regardless of price. However, the passive filters of Ensis and Stilla have proved to excel beyond that in the extent of the frequency band for phase alignment, with Aequo Audio aligning both midrange and tweeter full range for the most discerning ears/brains.
Speaker driver phase measurement showing perfect time incident behaviour and both drivers moving together in perfect synchronisation in their movement over virtually all frequencies far beyond the crossover band around 2.000hz.
Aequo Audio created a three-way speaker that acted as a super-coherent, point-source-like speaker by incorporating aspects into the design that are often overlooked by other manufacturers. With regards to average dispersion in energy, both in the horizontal and vertical direction, it is imperative for coherence between drivers that an optimal directivity curve over frequency is delivered by both drivers working together.
To establish a holographic sound-stage that includes transporting the listener to the middle of the original recording venue, surrounding the listener with the original reverbs and decay effects, whilst providing realistic imaging between the speakers at any height and depth, the directivity curve must be almost unidirectional in the mid-frequency band to ensure the correct energy dispersion in a good room. There should be a very smooth rice in directivity towards high frequencies, which helps bundling the energy towards the listener to avoid excessive harsh sounding energy by reflection of these frequencies against hard room surfaces. However, in the top octave it should rise not too fast and have enough width and height left in the energy distribution for a fully open and airy stage from a large range of listening positions. The latter is often a problem with one or two-way designs using a “full range” driver for both mid and high frequency reproduction. Furthermore, for enhanced coherency, the directivity over frequency should be free of the jumps which are usually seen in multiple driver speakers. Taken all in consideration, The Stilla directivity, can be considered very close to perfect.
Speaker directivity in db per frequency of Stilla. To attain the correct energy dispersion a good speaker stays within 3db below 3000hz, from the 3db base line (<6db), then starts bundling energy faster up to 8000-9000hz, then slowing its rate of energy-bundling again.
Another important aspect that was taken into consideration by Aequo Audio in the design of Stilla was the time domain where acoustical energy is produced for the full audio spectrum. The team ensured that the Stilla was an extremely fast and open sounding speaker containing high-speed high-controlling motors on the self-dampening midrange and tweeter membranes with low amounts of stored energy. Graphically combining the measured output of two unfiltered drivers in a ”waterfall” diagram, the transition of energy over frequency, with time of decay added, is a good tool for revealing potential coherency disturbing factors before applying the crossover filter.
It would be expected that from a 5 inch midrange driver there is some energy-storage in the 1-2k range by diffraction of its edges. Aequo Audio minimised this effect by choosing an optimal engineered shaped driver and, a cover in front of the midrange, close to the edges of the driver. Towards higher frequencies it is desired to have a nice decrease in stored energy without the further spiky energy storage effects caused by the ringing of hard cones or inverted resonant movement by the centre of soft dome tweeters. The Stilla is a fine example of very fast and coherent driver-behaviour in the time domain.
CSD Waterfall diagram of combined mid and tweeter response data of the Stilla (blue line shows a gradual trend of decrease in stored energy towards higher frequencies.
Focus on R&D with in-house facilities
Focus on R&D with in-house facilities
Determined to get an enhanced ‘musical message’ to a broader audience through dedicated listening rooms around the world and ultimately into the living rooms of all music lovers, Aequo Audio places emphasis on in house R&D and adopts an Octagon philosophy which has been incorporated into its company logo.
Aequo Audio’s first model, the Ensis Loudspeaker, launched in May 2016, won many prestigious journalistic awards. The success of this product has allowed the team to expand and enhance its manufacturing facilities and invest in new equipment including state of the art 3D printing, for rapid prototyping and testing, along with a fast and highly precise CNC German routing station.
The designers and engineers at Aequo Audio believe in the philosophy of their locality: innovation through collaboration, research and technology. This is achieved by utilising the advanced measuring facilities of the Technical University of Eindhoven along with having close and established relationships with local suppliers that are compliant to the extreme high standards in quality and precision., typical for Brainport manufacturers, such as the multi-billion corporation ASML, which is the global leader in chip making equipment.
At the time of developing the Ensis, we were already aware that the high quality material had excellent thermoforming properties, although it was still limited for small radiuses such as the “point” of the ellipse shape. For the Ensis, we use a custom in-house built 20 ton hydraulic press, for the multi-layered, multi-type wood shell, glued together and formed under high pressure. Now combined with our new industrial high-precision oven equipment, this same press can be used while thermoforming thick plates of artificial stone into the perfect Ellipse shaped outer walls of the Stilla speaker. The development of this process was extensive and included the production of numerous moulds, the usage of various tools and detailed measurements and evaluations at every stage before the design was ready to be fully optimized for ongoing production. The end result was an almost zero fall-out production rate and a speaker product that sets new standards in high-end acoustic properties of compact high internal volume speaker cabinets.