Mille LEGEND Subwoofers

Music fans who attend live concerts know well the emotions that low undistorted frequencoes without dynamic compression can arouse. For this reason, the HertzAudioVideo R&D created Mille car audio subwoofers

ML 2500.3 Legend

The design.

Music fans who attend live concerts know well the emotions that low undistorted frequencies without dynamic compression can arouse. For this reason, the Hertz R&D created ML 2000.3 Legend and ML2500.3 Legend, the two reference subs for the Mille.3

Legend line. During the long development phase, the designers set themselves just one ambitious goal: to transfer the emotions of a live performance to the car environment.

Thanks to a completely renewed design, the subwoofers have extremely compact size and are optimized to play in enclosures with reduced boxes. This choice of design combines two requirements hard to achieve up to now: reference performance and ease of


The Hertz electro-acoustic designers had the Mille Legend subs mount a CCAW (Copper Clad Alumium Wire) 100 mm (4”) voice coil, to ensure unparalleled heat dissipation capability compared to the average subs that mount voice coils with considerably smaller

diameter. A larger diameter ensures better stability of the voice coil during extended excursions, as that makes the voice coil less sensitive to undesired resonances, such

as for example the “rocking mode”.

Besides size, the voice coil features a new winding process called “In/Out”.

This technique, although more complex and expensive from a production perspective, provides the ability to obtain an even cooling of the different coil layers. With standard build methods, the internal layers, those close to the former, considering heat dissipation, are more disadvantaged than the external ones. In the case of In/Out coils, thanks to their build, the internal layers have same dissipation capability as the external ones.

The subs spider, made from CONEX, has been designed to work in perfect synergy with the 100 mm coil and to ensure maximum mechanical linearity during long excursions of the cone, that is made from paper with the add of mineral powders to increase stiffness

and damping.

Dynamic Compression

The musical signal is much more complex than a sine wave, since it is characterized

by continuous and quick variations of level, especially at low frequency range. Think about

the rhythmically pulsing of an electric bass coupled with the bass drum: at each pulsation,

the amplifier applies power to the subwoofer voice coil (Pe) which gets warmer (VC Temp)

as the track is being played, increasing its resistance (Rdc). The resistance increase

behaves like a bottle neck constraining the current flow, limiting the power the amplifier

can deliver to the subwoofer during the reproduction of the track. This phenomenon is

known as dynamic compression.

The IN/OUT wound 100 mm (4”) voice coil, employed in the ML 2000.3 Legend and in the

ML 2500.3 Legend, requires longer heating times compared to products featuring a

smaller diameter voice coil built with the traditional multi-layer winding method.

Therefore, when the most demanding musical programs are reproduced, the Mille.3 Legend subwoofers voice coil remains within the optimal temperature operational range,

reducing dynamic compression to the minimum.

This feature is fundamental to re-create the same emotion of a Live performance inside the car, and so to be able to appreciate the whole dynamic range of the different instruments.

To make the most of the capability of this special mobile voice coil, through the use of the FEA simulation technology, a specific magnet assembly has been optimized, employing a 5 mm thick Neodymium ring, capable of generating even, magnetic flux, also during the cone maximum excursion. The use of a 100mm (4”) mobile voice coil provided the ability to insert the magnet in its inside and not on its outside, as it is common in conventional designs, so to minimize energy waste maximizing efficiency and, at the same time, minimizing overall dimensions by adopting a compact design.

The movement of the mobile voice coil inside the air gap causes a ariation of the inductance value that, at high excursions, becomes significant, causing distortion. To keep this phenomenon to the minimum, a copper ring outside the motor pole called “Copper Ring” is employed, effectively minimizing distortion. However, using the “Copper ring” in the subs motor would have required reducing the air gap, thus reducing energy as a  matter of fact, with the result of losing low frequency level. For this reason, the Hertz electroacoustic designers went beyond that, developing a technology specifically thought for the Mille Legend subwoofers called “Aluminium Shorting Ring”. In this case, an aluminium ring inside the pole is employed, leaving the gap area free, preventing loss of energy in the low frequencies, though keeping the distortion reduction unaltered.

A powerful motor, capable of extreme performance, requires a frame extremely resistant to twisting stresses to unload all the power. 

This concept, applicable in car contests, is perfectly applicable also in electro-acoustics. This is the reason why the Hertz designers, through FEA simulations, designed a six-spoke compact antiresonant alloy basket with spider built-in vented holes. Together with the eight holes of the bottom plate and the motor central hole, these vented holes allow the cone to move as free as it needs making long excursions, eliminating every distortion due to acoustic compression phenomena.

The structure self-standing geometry adds to the overall mechanical damping, resulting

absolutely transparent to sound. Thanks to the combination of these technologies, the subwoofers can handle 1400 W musical powers and play the most demanding musical programs without any dynamic compression, taking the listener close to the live event.

eID (Elettromedia Identification) is the exclusive technology providing the traceability of the Mille.3 products from their birth on.

Once the test phase has been passed, the code linked to destination country/market is applied. When purchasing the product, by scanning the code, the user can check through the web the information about the product and can log into the registration page; by filling it out, the user will be entitled to one additional year of warranty coverage*.

This way the user will have the certainty of owning a genuine Hertz product, purchased through the official channel.


*in those countries where the agreement with the partner has been made.