Aries Cerat Symphonia horn speakers review preview

This year I’ve had a wonderful opportunity to experience Aries Cerat Symphonia horn speakers as one of my tripes enrouted me to Athens-Greece, meeting Stavros Danos, mastermind behind Aries Cerat. Fully fledged Aries Cerat system, owned by previous owner of complete Audio Note UK system was quite a revelation. Our host explained along with Stavros everything about the system and what led him to switch to Aries Cerat. 

His journey with Audio Cerat started slowly, but went into the fifth gear by each new component acquired. When Stavros lend him first component our host was completely mesmerized by  performance. During short time interval, step by step, whole Audio Note system was replaced into the full Aries Cerat based rig. Quite a turn of events!

System experienced was nor typical high-end audiophile system, nor Aries Cerat Symphonia horn speakers as a constituting part enrolled instantly into the Mono & Stereo Uber Audio 2015 specialities.


First day of my visit was planned for simple get in get out, few tracks sampling event. Not exactly. Forgot about time/space, food and drinks, fully immersing into the music. 

Evanescent sound from most speakers easily leave me untouched. Here, something different and special was on track. In absence of typical peripheral sound imprint, Symphonia speakers prelapsarian archetype sound nature resolved. 

I’m used to freckling nature of many if not most horn based speakers. Most of them sounds fibrously fragmented rather then harmoniously rich and palpable like Aries Cerat Symphonia have shown within first few track. Tremendous power handling ability, breaking many of the typical rules expected via this type of speakers, illustrated benign sound particles forming a clarity defined acoustical space. Quite a new dimensional path.

Sound at upper plane shall bring low level anxiety, unaltered, unassisted experience that's involving, coinciding with music and without any specific geotagging of the sound.

Stvaros Danos non condensed creations  resolves through painstaking processes. BIG way of thinking, never settling for the dramatic mood impression sole or false impersonating embrace resilient nature across all of his product line. Proper sizing comes mandatory. High-end companies trend in downsizing non exclude expensive and exotic ultra high-end audio products due to many reason. Commercial leveling pops up to quickly. Stavros’ components might appear monstrous in comparing. Yet, utmost quest leaves no place for mediocrity reasoning.

Wholeness presented with Symphonia conveyed raw musical nature rather then sonic mildness. Different league! Live music, always closely connected with pure energy leveling demands firm, mighty projective fullest bloom pure energy transfer. Symphonia stands  still in such projection. Full scale impression level is way beyond most dynamic speakers big boys scope. Distortion coating is to obvious. 

Aries Cerat Symphonia demands whooping 1 m x 1m space …


Symphony horn speakers DNA calls for serious homework. 

Stavros Danos was early on fascinated with the horn speaker technology, embracing it as a way to go. Years of research and reading resolved in his appreciating of the prior art. Consequently by comparing and listening he failed to be enthused with contemporary horn designs and fundamental flaws associated, killing real horn advantages and introducing the problems of their own. He wanted to embrace early horn era designs, taking a step further with help of modern advanced technology.

The Symphonia speakers began as Stavros Danos personal project, long before the establishment of the company in 2010.

Many of his ideas and concepts could only be materialized after the acquiring highly specialized equipment, such as 5-axis work station with the highest Z-axis envelope possible, ideal to carve anything from chosen materials.

Both Contendo and the Symphonia were developed side by side. Experiences gained on both fronts open up the exchange concepts and innovations between two development platforms. For example horn loaded ribbon tweeter innovative 360 degree flare was originally developed for the Contendo, but utilized in final Symphonia design. Same goes for the solid wood midrange horn, with it's special drop shaped enclosure that eliminates all diffraction. Used and implemented also with tweeter horns. This originated with Symphonia and later used with the new flagship cost no object Contendo.

Symphonia was not an isolated project, but a design that grew along with the company by adopting many breakthroughs from other speaker projects.

Aries Cerat proprietary variable slope filters, with the constant delay characteristics, were being developed for many years via company smaller speakers. At the end Symponia acted as  final developing platform.

Lots of R & D went into eliminating problems associated with horn physics. When not taking in consideration they result in mediocre performance with nasty sonic traits wrongfully, attributing with horns in general. 

Badly designed horn speakers sounds much worst than a badly designed conventional speaker. If a horn speaker design is being  compromised from the beginning, either from budget limitations, built tech resource limitations of simply lack of horn physics understanding, horns are better to be skipped.

When properly designed horn speakers represents ultimate electro-acoustic transducer. Aries Cerat Symphonia and Contendo speakers follows this profoundly. 


I’m often teasing speaker manufacturers to state real down to earth technical specifications. Especially with sensitivity. Most of the speakers are measured 6db lower than the rated sensitivity. It is easy to spot and point designs exaggerating only by analyzing the core design, election of the drivers etc. Rating sensitivity should not be the race. Just plain state of the actual affairs.

Faked sensitivity rating extend to all speaker designs. Not only hours. Marketing modus operandi pushes ratings to reach the broader customer base, including owners of smaller amplifiers.


Full range, full spectrum horn sound calls for differentiating true horn speakers from waveguide, directivity control apparatuses, hybrid designs etc.

Horn loading is something completely different in terms of physics, approach and end result. Any categorization of the horn based speakers is shady and confusing. 

Horn speakers is acoustic impedance transformer. Car mechanical analogy of 1hp servo motor coupled to a feather like axial load comes very handy translating to direct radiating driver. Energy transfer of such system is very poor, of low efficiency and most of the mechanical energy being wasted

On the opposite extreme, 0.1hp servo motor coupled with 1m diameter steel disk sports extremely low energy transfer for opposite reasons, usually related with planar speaker designs. Maximizing transfer of electromagnetic energy to acoustical “  motor impedance must be equal to the load “impedance”.

A horn act simply as a gear box, matching the impedance of the load to the output impedance of the motor. Not exactly a free lunch however as horns are bandwidth limited, sacrificing bandwidth for the efficiency. 

Full audio spectrum reproduction should with such logic separate s specially designed horns for specific bandwidth intended. In theory, with world data at hands Stavros feels, how they should handle 1.5-2.5 octaves, even if the drivers loaded with the horns can handle much wider bandwidth.

Limited bandwidth of each horn demands additional drivers,  increasing cost, size, and weight with full horn loading of the entire audio spectrum. Horn cut off frequency is a function of size. You cannot bend the rules, thus so many hybrid designs.

Full spectrum horn sound is suybordante to horn physics.

Usable extension of first two octaves via bass horns calls for certain length and “mouth” area for given cutoff and lifestyle stylish speaker idea vanishes instantly. 

Aries Cerat bass loading is quite straight forward, even though the technical solutions are not. With Symphonia 3m of horn length is related to 3300 cm2 of “mouth” area. Usual norm is shorter horns connected with limited bandwidth and presence of ripples throughout the passband.

Symphony implements tractrix flare instead of the conical, strictly avoiding sharp corners, deviation from actual theoretical geometry and no abrupt curvature changes.

Standard folded horns construction with conical sections of wood sheets, forming successive conical section trying to geometrically approach a conical horn was off the table…

Aries Cerat owned 5-axis work station with the 5m3 work envelope gave them capability for designing and manufacturing a true tractrix horn with 25 vertically stacked sheets plywood meeting all criteria need. Vertically stacked sheets of plywood can also withstand the high acoustic pressure present inside of bass horn.
Aries Cerat Symphonia midrange horn is tractrix horn,modified with 360 degree  diffraction-less flare. As such it should had a cutoff at least 0.5 octave lower than the crossover frequency and 330Hz horn was specifically designed.

The horn and bullet shaped enclosure is manufactured from solid plywood block with thickness of up to 15 cm.The poplar plywood used was chosen over other types of plywood as it carry twice the strength/weight ratio compared with other types of plywood. Energy storage is thus halved.

Unique flare is designed to eliminate all possible diffractions, inartistically to other horns based designs. Diffraction is one of the major sources of the so called typical horn sound character. Properly designed horn based speakers do not and should not have any sound of their own.

Symphonia completely eliminate diffraction coloration usually smearing transients, with unique 360 degree bullet-shaped solid-wood horns.

11 kg, 4” oversized titanium driver, with a massive magnetic system is connected to the multi-tap transformer can tune the speakers according to each room’s acoustics.    


The development of the Symphonia’s tweeter was spread throughout a long three year journey. Stavros was always fond of Raal designs, yet normal direct radiating ribbons lacks the punch and dynamics of a good HF compression driver. However no compression driver can resolve with details, accuracy and bandwidth of a true ribbon transducer. Getting the best of both worlds embarked for a new quest.

A normal ribbon is not designed to operate with high acoustic pressures at the “throat” of a horn. Special ribbon developing was mandatory resulting in Raal tweeter with modifications.

New horn flare design is loading the ribbon as a true horn and not as waveguide or any directivity control apparatus. The line source emission characteristic of the ribbon made this task extremely demanding. During the process total of 15 different flares were designed, build, measured and discarded before settling with the final design.

Aries Cerat unique diffraction less 360 degree horn technology was implemented, but now with the ribbon horn, making the time domain performance of the tweeter unmatched.

Diffraction is secondary sound emission, and takes place in geometry anomalies, transitions of geometry and changes in curvature. It is very much audible and almost impossible to eliminate. In horns, diffractions are present on the horn termination for round horns. In rectangle horns the problem is even worst.

Expanded 360 degree horn maintaining the flare curve’s second derivative constant, keeping the curvature slope constant.

Precise measurements were  made with each horn iteration to match the simulation and theory to it’s performance. In his quest Stvaros founds, how variations of just 0.2mm bring detrimental effect on the performance of the horns. Anyone can imagine what a challenge this was.

The ribbon-horn combination response is shaped to measure flat from 3KHz upward, and can deliver detail and resolution that only the best of ribbons can, combining a solid punch and dynamics of the best HF compression drivers. Distortion numbers at 114db are lower that those of the best dome tweeters at 95db.


Horn speaker done right acts a true magnifying lens of everything in system chain. We can call them unforgiving. With highly sensitive horn speakers being driven at normal listening levels first few milliwatt are of utmost importance.

Low passages, ambience, sense of space, timbre are very well  hidden many db below the level of fundamental instrument notes.  

Many sensitive speakers are driven with just a few watts of power for peak signals, thus integrity of the signal in very low power output is essential for the highest reproduction.

This is where solid state and most push pull designs fails. The first milliwatt!

Heavy and inefficient speakers can “perfectly mask amplifier first watt artifacts, yet horns are very direct and unforgiving when driven with amplifiers designs created for the conventional speakers.


Many times past horn designs goes to quickly into into the same labeling. Many of the old designs are landmarks of audio reproduction can show the new guys how job should be done.

Surely some of the old designs were very much flawed and extremely colored for today’s standard. One must be careful and evaluate each design on its own.

Problems of contemporary horn speaker based are associated with two thing.

- The lifestyle-oriented design 
- the lack of knowledge of basic horn physical principles

Sadly many of the design choices are made with aesthetically  priorities in mind rather then prioritize function and especially horn physics.

This is clearly a matter of deliberate design choices, many times ignoring basic horn principles.

Old speaker engineers had different priorities, although without CAD-CAM simulation systems and and programs, their designs respected the basic and advanced aspects of horns, with forward thinking attitude.

With Symphonia project Stavros Danos decided addressed problems with the implementation of horn theory, bring solution to practice and realize actual production. No shortcuts taken approach led to custom diffraction-less horn, Aries Cerat specialized constant GD filters, unique bass horn design and special tweeter. Symphony materialized into a platform referencing to how contemporary high performance horns should actually sound and forming a speaker design small enough fit though normal doors (although only disassembled).

Horn speaker designs requires addressing some of the issues that  physics dictate.

- budget issues
- manufacturing capabilities 
- technical knowledge
- aesthetics-styling 

Going into over-stylizing and neglecting basic facts results in mediocrity. Many would be better of with conventional technology speaker design as badly designed horn speaker sound much worse than a badly designed conventional speaker. Fact!

Horns physics dictate all of the aspects being addressed with utmost attention.

Many if not most horn designs on the market fail to address proper flare for the bandwidth and use too wide bandwidth for a specific horn. 

A specific horn has a specific bandwidth and should operate optimally. Usually, designers “stretch” the horn’s passband to get away with less horns/drivers for a particular design

This makes design smaller or aesthetically more appealing, easier to manufacture, making less parts needed. Still. 

Horn operating in the wrong bandwidth presents high order and linear distortions. Flare accuracy is very important; the higher the frequency more accuracy of the flare is mandatory. 

Aries Cerat tractrix flare was chosen for the best measurments and subjective performance. 

Stavros feels strongly how rectangle horns present high order distortions and many diffraction sources. Horn diffraction problem, is the major factor in creating the honking sound that most horn are associated with.

Symphonia drop shaped midrange and tweeter horn enclosures with bullet shaped 360 degree horn flares addresses this. Painstaking to design and execute, but this solution seems to avoid the hubris existing in other designs.

Looking at many popular modern horn based speakers reveals improper implementation of the drivers. Not all transducers are suited for horn loading and as such misbehave when loaded with horns. Proper drivers are usually expensive and hard to aquire. Finding the best driver for the intended bandwidth is a complex quest as technical specification can only indicate some of the reality when used. 

We have all sort of construction materials being used for horns these days. Fact is, horn presents sound pressure levels exceeding many times the pressures in conventional speakers. Plastic or aluminum horn however thick it may be,  will ring and resonate and color the sound immensely. Seeing some made from the thin plastic material… Complete nightmare.

With Symphonia listening and measuring tests of 2.5 cm thick composite 330 Hz tractrix horn compared to an identical stacked poplar ply wood horn with 15cm thick walls measurements of burst decay and listening tests revealed how plywood horn is vastly superior, even though 3 cm composite horn is much thicker than  the market’s standard. Making 15 cm thick plywood with mould injection is much costlier. Stavros always goes for the ultimate.

Horns are also very sensitive to their termination geometry, geometry follows after the flare (mouth) ends. Discontinuities of the geometry drastically changes in curvature generating secondary emission. This delayed emission returns back to the horn throat and horn driver and radiated towards the listener. This are very audible horn diffractions especially with horns installed on baffles.


This is the first part or the review. In second part I'll focus on music and conclusion. I'm sure you could find more then enough trough the preview to captivate you imagination. These speakers are unique creations and deserve all the high praise. Not finished yet, but I'm happy to announce that Symphonia will receive my most precious acknowledgment via Mono and Stereo Editor Choice Award.

Stay tuned.

Text: Matej Isak

Price: Starting from 55.000 EUR, depends on the finishing and version.


Sensitivity : 101db
Frequency response(-3db) : 35Hz~100Khz
Weight: 150 each
Dimensions : 930mmW X 1300mmH X 880mmD

Filter design.

The external crossover, consists of three constant group delay filters. A constant group delay filter, is our own proprietary design, which alters the attenuation slopes of the driver filters, to shape the phase(and doing so the GD)in such a way ,as to provide maximum GD linearity.

Using this specific filter technology to the physically time aligned horns, the Symphonia speaker present time domain performance which is near perfect, and a frequency response with a maximum deviation of +-0.5db (250Hz-20KHz).


Aries Cerat LTD 

52 Vasileos Pavlou A’
Limassol 3052


P.O. Box 55589
3781 Limassol

Fax: +357 25565916
Mobile: +357 99307099