_vKi is the alliance of several innovations dedicated to the reproduction of the full dynamic range.
It offers a new state of the art in loudspeaker design and acoustic performances.
Preserve the full and exact sound dynamic range is a fundamental feature
Music is dynamic
The audio signals must use very wide dynamic range to reproduce the real sound wave.
The human ear isn't only a "pressure sensor" as a microphone, but also a "transient sensor": The sound perception is leading by sound variation pressure.
In this regard, the human ear is extremely sensitive and accurate on very wide dynamic range: We can perceive sound pressure variation from 20µPA to 200PA.
The frequency response and other basic data used for a century are important, but the next progress of sound reproduction lie in the transducer dynamic capability.
Example of music signal - length : 3.15min
Translate the physical needs into technical requirements
The audio signal dynamic is a complex topic, including several different features.
We can distinguish the long term and short term dynamic range:
1- For on music live concert, a movie, during ~2h, we expect the transducers provide the same dynamic performances during the full duration of the event.
It requires to keep all transducer parameters unchanged and stable in any circumstances (voice coil heat transfer, suspension stiffness, ...)
2- If we analyse the audio signal in shorter duration (few seconds), we notice significant amplitude variation in extremely short time.
This transient signals require acceleration capability and exemplary behaviour in the time domain, which means high and constant force factor, no distortion.
Preserve the dynamic range under realistic sound level
In technical language, preserve the dynamic range means to ensure the reproduced sound wave is proportional with the input signal.
Thanks to the large voice coil diameter and the constant force factor, the _vKi technology are closer from the real dynamic of the audio signal.
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Keep constant motion forces on larger cone excursion.
Usual woofer technology limits the force factor linearity around +/-8mm.
Usually, to enlarge this typical excursion, the voice coil becomes longer, heavier, or the nominal Bl [N/A] value decreases significantly.
_vKi motor structure, made of radial magnets, allows to reach high force factor value, and real large excursion capability.
In the same way, Kartesian spider technology provides linear and symmetric stiffness on very large cone movements.
These performances ensure more accurate cone movements under large excursion.
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Improve distortion where it does matter
Distortion is one of the basic features that a transducer must manage to be serious competitor.
Nevertheless, as other technical data in the past, the THD is tending to become a commercial criterion, losing its meaning and relevance in the process.
THD is static measurement, comparing the generated harmonics with the played frequency: This isn't comparable with audio signal, it is only a technical indication.
As the THD is already low in the mid-band area (~0.3% for 90dB at 1m), the _vKi technology makes the difference in low frequency, with significant improvements.
Furthermore, to get more relevant indication of distortion components, we prefer work with multi tone distortion, reaching the same improvements in low frequency.
Ensure transducer stability in any circumstances
The shape of the frequency response in low frequency, whatever the acoustic loading (sealed, vented, passive radiator, ...) is driven by the T&S parameters.
The resonance frequency is very important parameter because it affects others parameters (VAS, Qts, ...).
If the resonance frequency isn't the same in low and large cone excursion, it means the shape of the frequency response in low frequency isn't the same neither.
As a consequence, the dynamic isn't preserved and audio signal is disturbed.
_vKi drivers ensure stable Fs [Hz] on larger cone excursion, offering new level of performances, especially in low frequency reproduction.
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Comparison method:
We tested 37 woofers references, with diameters from 172mm to 190mm and retail prices from 60% to 200% of Wom185_vKi
Based on very different results, in order to provide relevant information, we created 2 groups to sum-up of the results :
- "Regular woofers", including vintage, esoteric and entry level products.
- "High quality" woofers, grouping the top the art products.
Next, we created average curves for the performances of each group.
Assembling details of _vKi transducers
Example of 185_vKi
1- U-Yoke: Made of very low carbon steel, it drives intense magnetic flux and ensure voice coil cooling.
2 & 2'- Aluminium rings: It significantly reduces the inductance modulation to improve the MD performances.
3- Yoke: Made of low carbon steel, it is specifically shaped to offer constant magnetic field over 35mm.
4- Dust protection grill.
5- Cooper ring: It reduces the inductance value by 50% and improve its stability according to voice coil position [Le(x)].
6- Cooper struts: It significantly protects the magnetic flux modulation from the voice coil current.
7- Radial magnets: Made of N40 grade, it provides 1.05T over 35mm height.
8- Frame: Built in injected Aluminium, is has been designed to balance the moving parts fixation and avoid any inner resonant cavity.
9 & 9'- Spider(s): Using Kartesian innovation, it provides the required and stable stiffness over larger excursion [Kms(x)].
10- Spider spacer: It allows dual spiders assembling without any air compression between both spiders.
11- Voice coil: It uses composite Titanium / Glass fibre vented former and short coil, most of the times only 1 layer.
12- Cone body: Built in advanced paper mixture, it uses hexaKone innovation to ally low mass and high Young modulus.
13- Surround: Built in NBR for lower mechanical lost, It uses different profiles according to driver purpose.
14- Dust cap: Mainly built in CGF, proprietary material with very high Young modulus and very good inner damping.
_vKi is an adaptable technology
Thanks to the construction detailed above, the _vKi technology can be adapted to specific requirements.
It is possible to reach any T&S parameters, overcome the usual constraints linking the moving mass, the force factor, the inductance value, or the R DC.
For the most ambitious projects, it is possible to transfer the _vKi technology into exclusive design, including unique frame design and other cone materials.
Contact us to start your uncompromised loudspeaker project:
Uncompromising quality
The _vKi products are engineered and produced in France.
The assembling of _vKi requires specific machine, including innovative and exclusive magnet charger for the stiff radial magnets.
Usually, those who use radial magnets charge each magnet before the assembling, which does not allow to use stiff magnets, do to handling difficulties and dangerousness related with intense magnetic field.
Thanks to Kartesian innovative magnet charger, the 8 magnets are charged in 1 time, after their assembling in the motor structure, with 280KVolts specific charger.
Kartesian controls the value of the magnetic field in the gap at 8 points, ensuring homogenous field over the full motor structure.
Every single part is controlled before its assembling : spider stiffness, cone weight, voice coil R DC... totaling 16 quality controls during the production.
Quality control report, is provided with each _vKi driver, showing measurements proceeded during production and results.
Each _vKi product has unique quality control number, which can be read on driver and report.
Kartesian archives these quality controls, including frequency response, impedance, THD, polarity, T&S, and complete batch traceability.
Price list according to quantity