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Aequo Audio Ensis Loudspeakers

08-11-2016 | By Wojciech Pacuła | Issue 87

Ivo Sparidaens, Concept Manager, and Paul Rassin, Marketing & Communications Manager, are members of a six person team of a Dutch company Aequo Audio that designed Ensis loudspeakers. It's the only product of this manufacturer (for now). Introduction of these loudspeakers to the market was preceded with five years of research, trials and errors and new takes on the subject. The work was based on some technical assumptions, but the final voicing was made by a group of people, including designers themselves, and a group of friends—audiophiles and music lovers, who spent countless hours in listening sessions.

Aequo Audio ENSIS Loudspeakers

As a result of these efforts loudspeakers were created that combine several, often conflicting, objectives. I must say that they represent a certain harmony—I mean in different aspects, such as: sound, appearance, setting etc.—which could not have been achieved by accident. Although perhaps in this case it had been, because from the very beginning its designers strictly complied to the principle they called "Octagon Model". By the way, it is probably not a coincidence that their logo resembles the Ring—you know which one...

Octagon Model

  1. Size and form - an audio product should be beautiful and become a harmonious part of the environment it is placed in—yet, uncompromising when it comes to sound quality.
  1. Room acoustics - Aequo Audio uses advanced measurement techniques, including excellent anechoic chamber, but it is only a starting point; it was not about achieving a perfectly flat frequency response in the laboratory conditions, but about adjusting it to the realistic acoustic conditions of any space used by music lovers. Adjusting the sound to a specific room is achieved using the ARPEC system: Adjustable Room (and) Extension Placement Controller and the techniques that assist a controlled sound dispersion


Tweeter. On the left it is shown, how does the classic "waveguide" work in the vertical position. The problem is reflection from the ceiling, but unfortunately the reflections from the floor are even more difficult to control, since the distance from the floor is shorter than the one from the ceiling. On the right you can see that a better balance between the reflections from the floor and the ceiling was achieved by tilting the cabinet of the loudspeaker to the back.

  1. Soundstage and imaging - the way of recreating soundstage is one of the key factors towards creating a high-end sound. One of the objectives was to make these loudspeakers "disappear" from the room and the other to achieve such level of imaging of instruments and performers that would create an impression of a live performance.


EHDL Waveguide: On the left there is a loudspeaker with a front baffle tilted back. On the right you can see the EHDL that converts part of the vertical sound energy into horizontal one, hence reducing the problematic reflections from floor and ceiling, and generating a much more realistic soundstage with better depth with more natural imaging.

  1. Loudspeakers placement - the company tried to avoid the use of techniques that narrow possibilities of loudspeakers placement in the room, such as: bass-reflex or dipole sound radiation.
  1. Purity - because one of the characteristics of the human hearing is high sensitivity to even extremely low distortion, one should aim to minimize them. However, one has to know what to look for and which of THD (Total Harmonic Distortion) are more important and which are less. The company assumed that in the frequency range to which we are particularly sensitive, one needs to find a balance between odd and even harmonics. To minimize distortion a special multi-layer cabinets were created, a hi-tech midrange driver, and a special attention was paid to put all the elements perfectly together.


Midrange driver measurements: The driver developed by AA delivers amazingly clean and fast performance. It does not have a problem with the "ringing" from the membrane break-in, which allowed them to use low-order filters in a crossover. This is achieved by symmetrical motor system and a special PP  membrane with perfectly damped own resonances. Hence it was possible to use a low-loss suspension, thereby reducing the compression.

  1. Precision - the resolution and phase behavior of the loudspeakers is another aspect that was important for the people of AA. Omission of bass-reflex and steep crossover filters allowed to bypass the problem of group delay phase in different parts of the band. It was also important to use transducers, which, thanks to the construction of the motor system were able to respond quickly and without compression.
  1. Amplifier matching - one of the key aspects when building an audio system is finding a proper match of an amplifier and loudspeakers. Ensis feature an active bass modules, which makes user's life easier, because bass performance is not dependent on amplifier used in the system. These are high efficiency speakers and a friendly load with their 8-ohm nominal impedance. So one can use almost any amplifier, including a low output one (eg. a tube one)
  1. Dynamics - some loudspeakers deliver a dynamic performance at low sound levels, other at high ones, which usually is a result of drivers chosen for particular design and their implementation. Audio Aequo tried to match these elements in such a way that dynamics and thus the emotional connection between a listener and music was similar at any position of volume knob.

A few simple words…


Concept Manager

June, 20th 2016, Eindhoven, Holland

Dear Wojtek!

On the first day back in the rainy Netherlands, we look back at a very pleasant visit to Poland. I am very happy to have meet you in person and want to thank you again for inviting us in your house. I am very impressed by your vast music collection with real special gems, and your passion for both music recordings as well as state of the art audio equipment.

Aequo Audio ENSIS Loudspeakers

Ivo Sparidaens - Concept Manager – oraz Paul Rassin - Marketing & Communications Manager during listening session with reference system of High Fidelity, Harbeth M40.1 including.

To prepare the speakers for the test the midbass and subwoofer drivers have been burnt in by a multi-frequency sine-sweep to x-max for a fixed time lapse, as we always do before taking measurements. The tweeter has not been truly burnt in yet, as we feel it’s better to play them in with music. Depending on music and listening level, you can expect around 3 days for the tweeter to get adjusted to its job and get the best natural performance. It is possible that you experience the subwoofer and midbass also loosen up a little more in these days.

As we stated during our visit you received a finished product for your review, although we still plan to introduce a few minor changes. We are still waiting for the final amplifier to arrive and we need to finish our auto standby circuitry. We also await the CE certification and finalizing product manual—your test will take place before we even start to deliver our product to customers. We hope these information will be useful for your review. If you have any questions don't hesitate to ask us—we'll be happy to answer any of them. Your opinion is very important to us.

I think the speakers will perform very well in a similar position as your current Harbeth speakers, only with probably a bit less toe-in.

See you again!

I hope that you can already see it—the Ensis are not another "me too" design (understood as: "I can same thing as other, just better"). It is a well thought-through product, the creation of which has involved many experts in different fields and no money nor effort were spared. Ivo Sparidaens and Paul Rassin, who visited me just before this test was conducted are extremely nice people who are also truly focused on their work. They are perfectionist with a bit of artistic talent too—a deadly combination.

Ensis is a three-way semi-active loudspeaker, with a soft dome tweeter and a very costly, custom made by Audio Technology midrange driver. Mr. Ejvind Skaaning and his son, Pera Skaaning are owners of this company. In the past Mr. Ejvind founded and for many years led Dynaudio and Scan Speak. Drivers sit in a narrow, rounded at the back enclosure, quite high up above floor level, and the front baffle is slightly tilted towards the back. The cabinet is made of several layers of wood of different density with a vibration damping material placed between the layers.

Speakers feature an active bass section—a side-firing woofer is placed in a sealed enclosure. During the test, the speakers were positioned with woofers firing outwards. Woofer is driven by a class D amplifier. The adjustment can be performed using two knobs, one of which adjusts the level of the sound and the second the cut-off point—it is a so-called analog ARPEC system. From our conversation it was clear that people from AA do not like digital DSPs that introduce unpleasant sound coloration, hence Ensis are completely analog loudspeakers (class D amplifier is also of an analog kind).

The bass module is powered from the power grid. Set includes two thick, but quite ordinary power cables. Replacing them with other chords might be problematic though, as manufacturer instead of IEC connector used Neutrik's PowerCon ones, with silver contact areas. In subsequent versions they plan to use the same type of connector but made by Amphenol, which—as Ivo said—are of much higher quality. Signal from amplifier should be delivered to a single pair of speaker terminals and there is no separate low-level one for the bass - hallelujah! Similar solutions can be found in other high-end semi-active designs such as Audio Machina, for example.

Aequo Audio ENSIS Loudspeakers

For the test loudspeakers were placed in exactly the same spots as my own Harbeths. While assessing them I firstly listened to the same albums I presented to Ivo and Paul. For this test as a source I used a two-box CD Player with CEC TX0 DAC0 3.0 + 3.0 (test will be published next month). The rest of the system was same as always. Adjusting the settings in the bass section took me ten minutes—it is simple, and the effects of the changes are clear.


Recordings used for the test (a selection):

  • Carmen McRae & Julie London, Carmen McRae & Julie London Bethlehem/Victor Entertainment VICJ-61458, "Bethlehem K2HD Mastering Series | No. 8", K2HD CD (1954/2007)
  • Depeche Mode, Violator (+Personal Jesus Maxi SP CD), Mute Records/Alfa Records ALCB-33, CD (1990)
  • Franc Schubert, 4 Impromptus D899 & D935, perf. Maria João Pires, Deutsche Grammophon/Universal Music Japan UCCG-50095, SHM-CD (1997/2011)
  • Frank Sinatra, Sinatra Sings Gershwin, Columbia/Legacy/Sony Music Entertainment 507878 2, CD (2003)
  • George Michael, Older & Upper, Virgin Records 8452032, 2 x Gold CD (1996/1997)
  • J.S. Bach, Sonatas & Partitas vol. 2 BWV 1001-1003, perf. Isabelle Faust, Harmonia Mundi HMC 902124, CD (2012)
  • Joy Bryan, Joy Bryan Sings, Mode Records/V.S.O.P. Records MZCS-1122, "Mode Vocal Collection", CD (1957/2007)
  • Kraftwerk, Live on Radio Bremen, Philips (?) 2561971, Bootleg, CD (2006)
  • Polish Jazz Quartet, Polish Jazz Quartet, Polskie Nagrania "Muza"/Warner Music Poland, "Polish Jazz vol. 3", Master CD-R (1965/2016)
  • Porcupine Tree, Deadwing, Lava 93437, CD (2005)
  • Portishead, Dummy, Go! Disc Limited/Universal Music Company [Japan] UICY-20164, SHM-CD (1994/2011)
  • The Oscar Peterson Trio, We Get Request, Verve/Lasting Impression Music LIM K2HD 032, K2HD Mastering, "24 Gold Direct-from-Master Edition UDM", CD-R (1964/2009)
  • Thom Yorke, Tomorrow’s Modern Boxes, Hostess | LANDGRAB RAB001J, CD (2015)

Designers of loudspeakers with a distinctive, good appearance that is closed to what people like to call a "designer" or "appearance focused" product, which in addition perform really well, have two ways to get there. One leads from the design/appearance to the sound and the other from the performance to the design. Both may work well and one could give a lot of examples of one or other approach that was successful. And yet, with all due respect to this type of efforts, one can not fail to notice that every time this is a kind of a "tug of war", it's like fighting with the matter—either to improve sound at the cost of design or appearance at the cost of performance.

It's easy to spot this "inner tension" even when it comes to the best products—after all it is a result of the game of  compromise. But it's not for the Aequo Audio loudspeakers. Even without knowing their origins, without talking to their creators, one can point to their most important advantage, which situates them at the intersection of these two, described above trends. They represent a perfect combination of design and performance. These loudspeakers look great, very modern and yet with their finish being a bit conservative, and at the same time they perform just as other classic design high-end speakers would. I realize this sounds a bit like taken from manufacturer's advertisement, but believe me—it's true and I can not express it in any other, better way.

Aequo Audio ENSIS Loudspeakers

What distinguishes them from the majority of "designer" products is this fantastic smoothness and silkiness of the sound. The old paradigm said that only narrow front speakers are able to "disappear" from the room, leaving us alone with the music. The amazing Audio Physics loudspeakers, as well as some others seemed to be a great proof of that. Personally, I think that the problem lays elsewhere—classic designs have problems with phase coherence of the signal and eliminating one of the potential problems, ie. a broad front baffle, concealed some of these problems. In my experience sound "breaks away" much better from the loudspeakers with a large front baffle—my Harbeth M40.1 being a perfect example of that.

With Dutch speakers, such considerations do not go beyond the initial phase, because they are not needed - they play like a single driver speaker. I never felt there was any problem with coherence between bass and midrange, but also between midrange and treble drivers. It's a very successful simulation of a point sound source. Therefore, most likely,  the soundstage is so incredible in its density and tangibility. One can not specify its beginning and the end, because it is very concise. Presentation of different types of reverb, natural acoustics captured during concerts is astounding. One immerses oneself in the sound completely, the bubble separating us from the music bursts easily.

But these speaker have also their own way of doing it—they build soundstage between them, it does not go beyond loudspeakers. These absolutely melt with the soundstage but are, however, border posts between the left and right edge of the scene. The listener's attention is focused in the foreground, but the sound can drift away to the the back of the stage, and with recordings, that allow it, it might surround us. After a while, I came to the conclusion that it was like listening through headphones in the sense, that I couldn't hear the room, but only the  music, and that the foreground was presented close to me and that this imposed a certain character to the whole presentation. This is the case in which we are transferred to another sound dimension, in contrast to the other speakers that bring instruments to our room.

In creation of this tight "cocoon" superior linearity plays the main part. I'm not talking about the "flat frequency response", because it is only one of many indicators that need to guide designers at the beginning of the design process, but about an impression of a perfectly leveled sound, from the bottom to the very top of the range. When you listen to old recordings, for example Frank Sinatra's recording of the 1940s or Julie London from the 1950s, you will get a nice insight into the recording (I'll get to that in a moment), especially into the most important element of the recording, ie. vocal. And when you listen to electronic music by Thom Yorke, sound will immediately go deeper and what matters most is a close, fast, warm electronic sound based in the lower part of the range. Ultimately, it doesn't really matter to Ensis what kind of music we want them to play because every time they deliver rich and very clean sound with energetic, beautiful sound sources.

Having active bass section suggests that one can play these speakers using as powerful bass as one wishes. It is not so, that's a mistake committed by many as it is sort of residue in our minds, a reminder of a home cinema era. The professional active and semi-active systems, as well as home audio ones offer only a narrow range in which you should adjust the intensity of bass performance in particular room. In other cases it will be a different but as narrow range. Active bass module relieves amplifier from the requirement of delivering high current signal to the loudspeakers. But it's not its purpose to boost the bass.

Ensis are able to deliver a beautifully coherent performance, but to achieve this we need to select the exact gain and cut-off freq for bass module, that will allow for a smooth performance across the whole band. Being able to adjust these settings is a clear advantage and yet whatever settings one chooses they still deliver a deep, rich and particularly energetic bass. They do not go as deep as my Harbeths and at the very bottom they are not so devilishly fast as the British "monitors". But, to be clear, no other speakers I had a chance to listen to in my system could match Harbeths in this respect. Dutch designs, however, belong to that small group of those that made me not miss this speed, reminding me in this regard the large JBL speakers. Their bass is clear, transparent and saturated enough to beautifully complement the extremely clean, warm midrange.

No, I haven't confused adjectives—these speakers play both clean and warm at the same time; they differentiate presentation really well but they also homogenize it (make it more coherent). These are tricks delivered by guys from Aequo Audio, but I know them also from other top-performance loudspeakers, such as Pure Audio Machina NSE (in Polish) for example. Also this one is a semi-active design with an extremely rigid and small volume cabinet. Although totally different drivers are used the sonic effect is similar. I can clearly hear in them a tendency to allow listener to listen to any kind of music with clarity good enough, and not to lose a fantastic resolution of the midrange driver, that is a clear star of this setup.

I never heard any hissing sounds. I do not know how they did it, but even with the recordings, which I knew had underlined sibilants—say George Michael's Older, released on the gold disc in (a little perversion won't hurt) Netherlands—nothing hissed. Treble wasn't rolled-off, withdrawn or veiled, I knew that there was more energy there, but it was all under control. On the other hand, with dark, warm sounding recordings, such as those of Julie London, added to the Carmen McRae album, speakers delivered a lot of information about the treble in the form of noise, voice's harmonics, etc. and sound did not seem to be closed-in.

Midrange was very resolving, and yet I could not get rid of the impression that it was warm; I had similar impression when listening to the Kronos Sparta turntable. Perhaps that is why the events in the front of the stage seemed to have greater energy. The phantom images did not have "bodies" precisely rendered, but they rather constituted together a certain structure, a whole with other elements on the stage. The sound tone and dynamics was greatly differentiated, and the soundstage was impressively large. The soundstage that was delivered as a  whole, from which one could deduce all the details rather than a sum of details—I hope you understand what I mean.

These are not loudspeakers that tend to discredit recordings, associated equipment, requiring from a potential user to choose one particular presentation character. They differentiate recordings really well, delivering thus sonic properties of each of them, but they do it casually, turning our attention to essence of music. So it is hard for me to identify the target group for these speakers—they play classical, jazz and rock music equally well.

But... At the end of the listening session I played the "Arriving Somewhere" track from Porcupine Tree's album Deadwings, that I'd listened with Ivo and Paul in my house during their visit and that I promised them to listen to also using their speakers. It was a true ride—these loudspeakers, despite their delicate appearance, played a fragment with powerful guitars in a way large speakers would, without compression, without hesitation, without shyness. A delicate passages were deepened, delivered in a... well, delicate manner. They presented  successive layers of the track with ease, freely, merging the big picture, so to speak, with details. It was really beautiful. Let it be a small clue as to their use.

A comparison

If I had to compare them to, already mentioned, Audio Machina speakers, the latter deliver a more open, more "immediate" sound. Ensis present a strong foreground, but it is always somewhat distant in relation to the listener—AM do it firmly, unequivocally. They also deliver more details, nuances. Ensis go deeper at the lower end, also bass has a more energetic character—in the AM it was more "in service" of the midrange and wideband Fostex driver.

So Dutch speakers would be more similar to my Harbeths. Despite obvious differences between them, there are also many similarities, such as a similar material of a midrange driver's membrane, and similar dome tweeter. Both designs deliver a warm but also selective performance, as well as incredibly resolving. Harbeths are a bit more dynamic and deliver lower, deeper bass. On the other hand Ensis' presentation is more precise, with a better differentiated treble. Harbeths deliver a wider soundstage and do not prefer events in the front of the stage so clearly. But Ensis delivers even more coherent presentation, so their soundstage is smooth and completely homogeneous.


These are particularly versatile loudspeakers. They look as designer's dream but deliver also a fantastic performance. Their only weaknesses—to be clear each audio product has them—are: slightly rounded lowest bass notes and a gently averaged dynamics of the midrange, or to be precise of the point of transition between upper bass and lower midrange. On the upside, it will be extremely easy to match them to an amplifier. They offer high efficiency, so one has to try them with some tube SET amplifier, but I would also match them with some high quality D-Class amps, such as those by Jeff Rowland, for example. That's obviously only a guess, as they performed amazingly well with my Soulution 710 which is a high-power, highly efficient and very transparent amp.

But that's how I see them as an element complementing a system with some fabulous tube amplifier (eg. Triode or Phasemation; in Polish) or with solid-state such as: Jeff Rowland, SPEC (in Polish), Tellurium Q or Lavardin. Any of these systems will be beautiful - literally and figuratively. I don't know any other case of such a "designer" product to deliver such a top-high-end performance. The Ensis are the first.


Ensis is a three-way loudspeaker, semi-active, with a Class-D amplifier driving the bass woofer. Passive section features two drivers—soft dome tweeter and  polypropylene midrange. The tweeter sits inside a small acoustic "lens", which directs the sound wave. Just in front of the membrane sits one more element—a phase plug.

Aequo Audio ENSIS Loudspeakers

Drivers are mounted on a narrow cabinet sloping to the rear. Its sports a two-layer front baffle, with a flat part on the outside in white or black color. It is made of very dense MDF. The element on the outside is made of a polymer containing certain minerals.

Aequo Audio ENSIS Loudspeakers

The back panel finished with wood veneer is rounded and is made of two types of bent wood—hard on the outside and soft inside. The whole is bent in the press that applies pressure of 20 tones. This plywood resembling material has nine layers—three hard layers, two soft and three rigid ones and finally there comes vibration damping material called Grey Matter Compound. It is particularly rigid, but it also exhibits hardness of a granite block. Its thickness varies depending on the location. The cabinet is so rigid that you can drive a car over it without visible deformation. And yet, on the inside it is still reinforced with horizontal ribs, similar to those used for boats.

Aequo Audio ENSIS Loudspeakers

Aequo Audio ENSIS Loudspeakers

The bass module is a kind of a "drum", with a driver on one side and the cooling plate for the amplifier on the other. The metal plate features two knobs allowing user to control the smart room size and speaker placement correction system. It allows user to adjust the sound character of the speakers depending on their placement in the room—next to the wall or far from any walls and obstacles. There is also a small light that indicates input overload. On the back of this "drum", directed downwards, there is a pair of WBT speaker terminals and a PowerCon power inlet. Loudspeakers stand on four rubber feet, which—if one so desires—can be replaced with spikes; the test was performed with feet.

Price (when reviewed): 20 000 EUR/pair


Dikkenbergstraat 1

5628 EA | Eindhoven 



Provided for test by:



Text: Wojciech Pacuła

Images: Aequo Audio | Piksel Studio | Wojciech Pacuła

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