The Hertz Mille line of reference car speaker products has been around for fifteen years now. On introduction some seven years ago, I was lucky enough to have a pair of the entry-level MLK 165.2's fitted to my Vauxhall Vectra estate (see issue 1 of Driving Sounds Magazine). They served me well until last year when the car needed to be replaced. The Mille's were still performing very well and the lucky new owner of the car still enjoys listening to them.
At the time they were fitted, I remember being quite blown away when hearing them in a test rig being used for listening tests by the designers. When they finally made their way into my car I was just as impressed - testament to the accuracy of the listening room the designers have in Italy where they were developed. It was with just a little trepidation that I received the news about the new designs that have grown the appendage "Legend" in their name. How, reasoned I, could they be considered legendary when they were brand new? Perhaps, they were simply a facelift of the originals and were designed to replicate the sound? In which case, the point in producing them could only be related to lowering production costs and that would be both uncharacteristic of Hertz and very disappointing.
At the time of writing, I am yet to hear the finished product but I have seen them. In fact, I have fondled, stroked and squeezed these beautiful beasts and if they are simply a face-lift then cosmetic surgery has come on quite some way since Joan Rivers sadly passed. I am privy to a great deal of technical data from Hertz relating to the design of their products and I can reassure you all that inside, they are not only an evolution but almost a revolution when compared to their predecessors. In fact, so different are they. It is difficult to know how to compare without getting unnecessarily technical about cone geometry, shorting rings, spiders, baskets and all the other important elements that can effect the performance of a speaker. Instead, I will simply offer a few key design features until I have had a chance to listen, which will be before we go to print with the magazine.
Since 2005, Hertz have been employing techniques and equipment in speaker design developed by eminent thought-leading physicist, Prof. Dr. Wolfgang Klippel. Mille Legend has undergone a great deal of work in every physical and electrical parameter using Dr. Klippel approved Finite Element Analysis which allowed designers to "try" different materials and technologies on an intrinsic design to accurately predict what effect these changes would have on the final design. Through painstaking research just about every element has been re engineered. Woofers and subwoofers use patented V-cone technology. V-Cone relates to the profile shape of the cone. This is used as it adds rigidity to the cones without adding weight. The aim is to have a cone that moves as much air as possible while holding its shape. The ultimate goal is to make a "perfect piston". In Mille Legend, the geometry of the cone has been adjusted and a "boundary-free" cone surround introduced to allow greater travel or excursion. The cone itself is slightly shorter to keep it more compact but this has also improved linearity or its ability to hold shape at differing levels. The paper cone has been treated with a secret recipe of chemicals offering further stiffness whilst maintaining the legendary natural openness enjoyed by current Mille owners. The new cone shape has also, according to Hertz, improved dispersion or width of radiated sound. Wide dispersion is vital when listening in the car where a driver sits very close to the right speaker (in England anyway!) and relatively far away from the left. To complement the changes to cone geometry and surround material, the cone suspension system, also known as the spider, has also been heavily reworked. One of the most important characteristics to benefit from Dr. Klippel's methodology is dynamic compression. This phenomenon negatively effects the ability of a speaker to accurately interpret high's and lows in music and is very important when listening to fine details which add greatly to listening pleasure.
Subwoofers benefit from a brand-new 100mm voice coil with the windings both on the inside and outside of the former. This results in much more effective and regular cooling resulting in a more linear performance and lower distortion. Magnetic flux and therefore power and efficiency are increased by mounting the magnets on the inside of the voice coil rather than the outside. Due to increased power, the whole chassis has been engineered for additional rigidity, as has the new six-spoke anti-resonance basket. Further cooling measures are included in the design of the new Mille Legend by way of eight vent holes in the base plate ensuring that heat is efficiently dissipated from the voice coil.
Mille Tweeters have been considered as the benchmark for many system builders for many years and designers had to take great care that any development work carried out truly enhanced performance without removing any of the previously enjoyed characteristics. As with woofers and subwoofers, the goal was to reduce distortion while increasing efficiency and linearity. This has been achieved I am told, by a combination of motor assembly improvements and adjustments to the geometry of the tetelon dome. However, another desirable improvement was to be gained by optimising the rear chamber of the tweeter resulting in a lowering of the resonant frequency to 900Hz. This allows the tweeter to reproduce lower frequencies, offering an overlap with the upper frequencies of the woofer. This is important to ensure a smooth transition between mid and high frequencies. In theory this should benefit the 2-way system in particular allowing a far more stable phase characteristic. This can sometimes become an issue with three-way systems.
In conclusion then, Mile Legend should be more efficient with reduced distortion, improved efficiency, a more linear performance and run cooler. That is a bold claim but, having seen Hertz in action at close quarters, I fully expect the claim to be completely confirmed under critical listening conditions.
So as this is a sneaky-peek rather than a finished article and I have not heard them, this is where I will leave it for now. You can find full spec and more information at www.fourcaraudio.co.uk and of course, read the results of my first listening experience in the next issue of Driving Sounds Magazine.