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Rendering of newest Aries Cerat hornspeaker
with 125cm midbass horn and Raal tweeter
  "The Gladius is the result of our efforts to design a conventional speaker. We usually design hornspeakers. The thing is, the only good horns are those built without compromises. Compromised horns make for horrible results. This mandates big horns. Our top speaker uses full-size tractrix loading and is an absolute beast which occupies 35m² just to set up. What we wanted for normal applications was the best possible direct-radiating speaker. The midrange is key to a good full-range speaker. Leaving aside compression drivers, we looked for a transducer with the highest possible treble extension. This usually means better breakup behavior to transcend the nasty breakups of ceramic and metal drivers. Perhaps the best midrange in the business comes from a small Alnico driver with a cellulose/mica diaphragm. We modified its cone to further flatten the frequency response but managed to keep its cone weight to 3.5gr.

"With loudspeakers baffle diffraction is a major issue. Many designers filter for the rising baffle-step response but don't attend to diffraction issues. We knew that the driver had to be baffleless and encased in a super-stiff structure. The next step was to machine a bullet-shaped enclosure made from Plywood using our 5-axis CNC. The bullet wasn't sketched out to appeal cosmetically but to exhibit linear curvature variations throughout its profile. Combined with the super fast tweeter, the step response is very clean with no delayed secondary acoustic emissions.

Aries Cerat at Athens hifi show with TuneAudio hornspeakers

Aries Cerat Gladius as shown by the Greek AVClub audio forum

"Coming to the tweeter I first heard of Raal ribbons a few years ago. Since then I find that no compression driver or tweeter of any other planar architecture even approaches the quality the Raal is capable of. Aleksandar was very helpful getting us the ideal unit for the Gladius. Sub 500Hz is the base of all music. We gave much attention to getting the best for the bottom octaves. Bass reflex was rejected from the beginning. We believe that the technical drawbacks to any bass reflex design preclude its use in a quality speaker. Horn loading for sub 200Hz coverage means hundreds of liters and huge mouths. That's why acoustic suspension came into play but not many drivers proved suitable for our goals.

"We needed fairly good extension down to 45Hz and perfect transient response. This meant perfect group delay. We also wanted a reasonable cabinet volume. After experimenting with certain mainstream drivers I discovered Acoustic Elegance from the USA. We were impressed by their specs and a built quality that was second to none. After many prototypes we settled on a modified 12’’ woofer with Lambda motor from them.

"The crossover design was the most time consuming and stressful to get right. With our super-quality transducers it was fairly easy to make the speaker measure absolutely flat. But we all know how measured performance doesn't tell the whole story. The speaker must deliver music in a most convincing fashion. We came up with several crossover variations all of which measured almost the same for off/on-axis amplitude and distortion. After untold hours of microphone/ear fine tuning we settled for the version that subjectively sounded the most natural to us.
"Of course we didn't shoot in the dark. We optimized the slopes and crossover points for linear group delay in the driver pass and stop bands. The graph above shows the group delay for the Raal with three different crossover variations at the same cutoff frequency. The group delay-optimized version was obviously our choice for the production speaker.

Crossover tuning in the Aries Cerat listening room. The graph shows a comparison of the raw Gladius midrange/tweeter response of two very different very early versions of the crossover. "The FR was very close between them but they sounded nothing alike. Frequency response measurements alone are really only the tip of the iceberg in any serious speaker design work."

"Typical crossovers are identified by their electrical order (1st, 2nd) and Q (for example a Butterworth Q of 0.707). Slopes specify the rate of attenuation in the stopband, i.e. 6db/octave stopband attenuation for a 1st-order filter, 12dB for a 2nd order. Our variable slope varies the attenuation rate in the stopband so the phase derivative—group delay—is as linear as possible. This function is not user adjustable but we do provide a service in which the crossover can be custom tailored to your room and preferences. All our crossovers come with a bypassable  filter. That cuts or boosts the narrow band between 90-120Hz which is usually problematic in typical rooms. We recommend leaving the filter alone but that's up to the user. As for our company's name, cerat is latin for κερας (keras). That was the Ancient Greek word for the type of horns we listen to. The animal horn is actually not the original meaning. Aries of course is the ram. He represents the mouflon of Cyprus. Our logo replaces the ram horns with actual horns. Our motto nil satis nisi optimum means 'nothing but the best is good enough'."