Since its introduction in 1999, the Mille series has always had one goal: to be a reference for the enthusiasts

ML 1800.3 Legend

Continued evolution to turn into Legend.

Since its introduction in 1999, the Mille series has always had one goal: to be a reference for the enthusiasts. The Hertz designers’ commitment has been rewarded by both the International press representatives’ and the in-car listening enthusiasts, not to forget the

several awards collected during the time.


The Hertz Design team approaches each new project as a continuous challenge: driven by their passion for music reproduced in car, they constantly improved the performance level compared to the past. To make the difference in your car audio system today.

The way a speaker is designed is in continuous evolution: Hertz has always invested in research and development. For this reason, from 2005 Hertz joined the “Klippel” certification program. In order to be allowed to use the “Verified with Klippel” brand, the Hertz R&D electro-acoustic engineers were trained and keep themselves periodically up to date with regards to the different systems for the speakers design, he development and quality control: Klippel DA-2 & Klippel Scan Vibrometer (Designed) – Klippel PM-8 (Developed) – Klippel QC (Tested).

Huge amounts of resources have been employed in the FEA (Finite Element Analysis) simulations which, through a long phase of material characterization, led to the optimization of each cubic millimetre of the speaker, giving the advantage of predicting performance and sound behaviours in their final application: the car environment!

All the results of this research course, focused on the cone geometry and their modal analysis, on the surround and spider optimization, on the thermal and magnetic advanced

modelling techniques, allowed to achieve an ambitious goal: to improve the Mille line, a reference product for the enthusiasts.


This constant evolution during the years nurtured the myth of the Mille line which, in its latest expression, has been deservedly embellished by the adjective “Legend” to celebrate its fifteen years of presence in the market.

In car FEA simulation

During these past few years the Mille line woofers have been the choice of many enthusiasts looking for extreme performance; with ML 1650.3 Legend and ML 1800.3 Legend, the Hertz designers increased again the limits of achievable performance for

components designed for door installation.

The ML 1800.3 Legend has been thought and designed for the enthusiasts attending contests who need a component merging the timbre accuracy of ML 1650.3 Legend to a wider extension to the low frequencies thanks to the large emission surface, higher power

handling and control which only a 50 mm voice coil can ensure.

To get to these results, the R&D staff performed extensive incar voicing sessions, after building several prototypes with the FEA simulation method and testing them with a wide array of measurements carried out with the Klippel® suite.

Like in the suspensions of competition cars, the surround must stand the most extreme working conditions to ensure maximum stability and symmetry at high excursions, and so to achieve impact and extension to the low frequency range.

For this reason, the electro-acoustic designers developed a new surround-basket gluing system called “Boundary Free Surround”. 

This technology, employed on all the Mille.3 components, provides the ability to achieve wider emission surface of the cone compared to speakers with same diameter; that way, the cone manages to move a bigger mass of air, so it produces more acoustic pressure.

This special surround is built from highly pure IIR butyl rubber, ensuring extraordinary thermal and mechanical linearity.

The cone geometry has been subject of in-depth studies with FEA simulations and measurements performed with the Klippel Scan Vibrometer; all that led to the optimization of the V-cone® profile. In the subwoofers and in the woofers, to reproduce the lowest frequency spectrum, the cone needs to move a remarkable amount of air, so it is forced to make long excursions moving like a piston does. The V-cone® profile prevents the cone from deforming during its course, ensuring that the “piston” works in a correct position, maximizing the production of acoustic pressure. In components of smaller diameter like the ML 700.3 Legend midrange, the exponential profile, with the absence of traditional dustcap, gets close to the perfect one generating exceptional dispersion at mid-high frequencies.

Suspension stress test

To ensure extraordinary power handling and very high thermal stability even with tracks especially rich of bass frequencies, ML 1650.3 Legend features a 36 mm mobile voice coil. This size ensures the best compromise between power handling and high-frequency response. For ML 1800.3 Legend a specific CCAW (Copper Clad Aluminium Wire) 50 mm diameter mobile voice coil has been designed. Thanks to it, the woofer can handle very high power with powerful low frequencies and without dynamic limits.

For the woofers, a specific solution to minimize distortion. Using an aluminium cylinder external to the central pole it’s possible to obtain an exceptional parameter stability, besides improving mid frequency response compared with the pole internal shielding that is featured in the subwoofers. The feeling you have when listening is one of utmost control

of the musical signal with an impressive dynamics.

The motor assembly expands around a Neodymium ring with unique sizes. The magnetic flux achieves amazing values and ensuring absolute thermal stability, bursting dynamics and total absence of dynamic compression.

Further to an extensive research performed with the FEA methods, the Hertz designers decided to reduce the cone profile, achieving an even more linear frequency response in the mid range, the most important range for the reproduction of human voice and

fundamental for timbre balance.

The gap of the three back spokes has been further reduced, to keep air resistance to the minimum, ensuring a more controlled movement of the cone and re-designing the spider geometry for a higher speed.

The basket is made of a special aluminium alloy, significantly damping the mechanical resonances between 800 and 1300 Hz, transferring all the precious energy only to the cone membrane.

ML 165.3 Legend enjoyed all the innovations introduced with the other woofers, although its design has been developed from a high density ferrite magnet compound .

This build difference characterizes the sound of this woofer, offering a slightly higher punch on low frequencies, with consequent higher overall dimensions.

Also ML 700.3 Legend Extended Midrange features the V-cone® geometry upgrade, the Neodymium magnet assembly and the threespoke anti-resonant aluminium alloy basket with vented holes.

Thanks to these technologies, as well as the Boundary Free Surround, taking the

diameter emission from 60 to 65 mm, the midrange will provide extended, properly

damped low frequency response, as the component will be filtered especially at the low frequencies, for excellent combination with the ML 1800.3 Legend, to build an ultra-performing system for competitions.

A copper cylinder outside the central pole piece ensures a linear inductance modulation, reducing distortion and offering improved high frequency response towards the internal aluminium shielding employed in the woofers. For this component, the Hertz designers chose to adopt a single-layer CCAW (Copper Clad Aluminium Wire) voice coil, ensuring

a more lightweight moving assembly; the junction point between cone and former has been optimized to improve high frequency response and minimize break-up phenomena.

ML 1650.3 Legend dispersion 3D simulation.

The V-cone® exponential profile without the traditional dustcap gets close to the perfect one, generating exceptional dispersion: thanks to the synergistic action of these technological elements, ML700.3 Legend boasts outstanding high frequency extension making it possible to build purist two-way systems in combination with ML 1650.3 Legend or ML 1800.3 Legend.

Thanks to this configuration, where there is only one cross-point, phase rotations are limited to the minimum, ensuring excellent soundstage and disarming timbre consistency. With the mid-high frequencies being handled by the ML700.3 Legend and the low ones by the ML1800.3 Legend, the whole audio range is reproduced with transducers built with the same materials and based on the same electro-acoustic structure; that doesn’t happen with woofer and tweeter, since due to its own nature the tweeter is different in materials and structure. The uniformity in materials and structures creates very high timbre consistency, so the speakers can “disappear” and leave room to emotions.

To improve a tweeter which was considered a reference since its first introduction into the

market is a quite challenging task which could only be performed by a continued evolution in time and maximum care for each detail that might affect sound. From these presuppositions ML 280.3 Legend has been born. Through the FEA simulations, the electro-acoustic designers carried out an extensive research which led to the optimization of the Tetolon dome geometry, to minimize distortion.

This optimization method led to a reviewed faceplate geometry for improved frequency

response and lower distortion.

ML 280.3 Legend dispersion 3D simulation

Another element of the tweeter especially important for sound is the rear acoustic chamber: the designers performed an exhaustive research on the geometry as well as on the employed damping material, achieving 50% increase in overall volume, to extend

response to lower frequencies with 900Hz resonance frequency.

The magnet assembly is composed of a Neodymium REN ring and extremely low carbon content steel plates, to ensure very high permeability, and, therefore, to raise the magnetic saturation threshold. These features guarantees total control of the voice-coil,

for a sound reproduction free from non-linearities with very dynamic transients.

The special design of the magnet assembly describes a perfect field symmetry in space, for an exceptional transfer Energy and linear movement of the moving assembly even in the most demanding audio passages.

The top pole piece covered with an extremely pure copper short circuit ring creates an anti-inductive effect, ensuring a linear trend of the impedance module. The CCAW (Copper Clad Aluminium Wire) voice coil guarantees an especially light weight and stiff moving

assembly. These technological elements interact one with the other, resulting in an extension to the extremely high, verified, frequency range of 28kHz, a record for a

tweeter featuring a 28mm voice coil.

The in-car listening purists prefer building minimalist systems with the least possible amount of speakers, to keep the phase variations around the filter cross points to the minimum. 

The R&D Department’s research met the enthusiasts’ needs: the optimizations applied to the tweeter provided the ability to relevantly extend the frequency response to the lowest frequency ranges, making it possible to buildtwo way systems combining the ML 280.3 with the ML 1800.3 woofer. When listening to this two way system, the listener is amazed for its timbre consistency and its wide virtual stage.

This tweeter has a thrilling design: its body is made up of a CNC machined aluminium block, for a mechanically inert, acoustically transparent structure, perfectly fitting in the other Mille Legend components thanks to the diamond-cut applied around the faceplate.

All Mille.3 Legend crossovers employ strictly selected passive components : they feature

bi-metallic capacitors and polyester dielectric, for maximum acoustic transparency. Thanks to their air wound inductors wound on up to 1 mm diameter pure copper wire, saturation, which is present with ferro-magnetic core coils, is eliminated, also if high drive currents are present. 

They also mount low parasite inductance, 8 to 12W power Wirewound type resistors. Thanks to the use of low inductance resistors for the  tweeter filter cell, the component can express maximum extension to high frequency since, even just a minimum inductance in series constitutes a low-pass filter, nullifying the ML 280.3 and ML 28 capability to reach the 28kHz barrier.


A unique impedance compensation cell has been mounted in parallel to the woofer, providing the ability for the filter to work on a load with even more linear frequency, confirming a record tonal balance.

The MLK 1650.3 Legend two way kit is dedicated to purists of sound, aiming at achieving maximum timbre consistency combined with very high dynamics and extremely extended frequency response.

Through a solidly built switch, the MLCX 2 TW.3 crossover provides the ability to realize a bi-amplified system, that is, to connect two amplifiers, or anyway two separate channels, to the crossover, so making it possible to drive woofer and tweeter separately.

The significant power increase with this configuration highlights all the features of the MLK 1650.3 Legend system, with all the advantages coming from the multi-amplification. Besides, thanks to the Mid-Contour and Hi- Contour controls, dedicated to the management of woofer cut-off frequency and tweeter cut-off frequency respectively,

the cross-point can be varied. Through each of these two“ Contour” controls, featuring a

two-position selector, the system frequency response can be fine-tuned, adjusting it

according to the different acoustics of the cars and the different speaker placements

and, most of all, the listener can achieve thieir favourite sound.

Besides, two additional controls have been dedicated to the most delicate component in terms of sound emission, requiring higher care in its positioning, the tweeter: a three-position control for the woofer emission level with 2 dB steps (+2/0/-2dB) attenuation and the Hi-Boost, a two-position selector providing the ability to emphasize the tweeter response beyond the 10kHz for situations where, due to space reasons or to the install cosmetics, it is not possible to install the tweeters on axis with the listener.

Thanks to the virtually limitless combinations of all its controls, the MLK 1650.3 Legend system can be entirely customized according to the components install typology as well as to the listener’s preferences.

The most fascinating aspect of this system is the sound: the most apparent characterist is the real sound you can achieve, recreating in the car the feeling of attending the live event thanks to a believable acoustic scene combined with absence of any compression, even in the highest dynamic musical peaks.

The MLK 165.3 Legend system is composed of the ML 28.3 Legend tweeter and the ML 165.3 Legend woofer with the MLCX 165.3 dedicated crossover. The woofer originates from the ML 1650.3 Legend, inheriting all its technologies such as the “Boundary Free

Surround”, the V-cone® profile Pressed-pulp cone with cotton fibres, the three spoke aluminium basket with vented holes; however, it has been designed employing a high density ferrite magnet assembly, characterising its emission in the mid frequency range.

The ML 28.3 Legend tweeter mounts the same Neodymium magnet assembly as the ML 280.3 Legend’s and features all the optimizations made with FEA methods on the dome profile, and that it shares with its “older brother”, except for the most esoteric features such as the die-cast aluminium faceplate, the CNC machined body made from solid aluminium block and the copper short circuit ring.

Like MLCX 2 TW.3, also the MLCX 165.3 crossover features the “Hi-Contour” control to adjust the ML 28.3 tweeter cut-off frequency and so the cross-point with the ML 165.3 woofer, according to the position of the two speakers in the car.

Through the tweeter three position level control, with 2 dB step attenuation, the level for a correct timbre balance can be fine-tuned according to one’s own tastes.

The MLK 700.3 Legend two way system aims at offering a mid-high frequency range of

excellence, to combine with a Legend woofer with a choice between ML 1650.3 and ML

1800.3 actively filtered in a multi-amplified configuration. MLK 700.3 Legend is composed of the ML 700.3 Legend Extended Midrange, the ML 280.3 Legend tweeter and the MLCX 2 TM.3 dedicated crossover that features the unique “Mid-Contour” control with its three-position selector, acting on the mid frequencies of the ML 700.3 Legend midrange by varying the cross-point with the tweeter to obtain the desired sound.

The tweeter level can be attenuated in three 2dB-step positions, to adjust emission to the position, to perfectly tune the emission level. The Mille.3 line has been designed with a very precise objective: to re-create the emotions of live music inside the car environment. The Hertz R&D team designed all its components – from the powerful subwoofers to the delicate tweeters- considering their synergy and with innovative spirit. This harmony shows through very clearly in the design of each product and in the sound of the systems.

Once again, making equal use of reason and passion for music, the Hertz designers managed to hit the goal, assigning the well deserved adjective “Legend” to the Hertz Mille.3 line.