DALI EPICON WHITEPAPER
INTRODUCTION Over the years DALI has continuously been pushing the limit for what can be achieved in terms of performance and build quality. With the introduction and steady evolution of technologies such as the hybrid tweeter module and wood fibre cones the important high-end segment has been the inspiration for DALI’s relentless research and development.
PRODUCTS The DALI EPICON series comprise of 4 models, closely linked together – yet specialized in their own field. EPICON 2 is a 2-way compact stand mounted speaker fitted with revolutionary, new drivers - 6½” woofer and the state-of-the-art 28 mm dome tweeter. The smallest of the floor standing models is the EPICON 6 which relies on a 2½-way system as – compared to the EPICON 2 – it features an additional woofer kicking in below 600Hz.
CABINET It has always been DALI’s aim to minimize the delay between the driver and the bass port. The position of the bass ports close to the woofers create as direct a connection as possible. The less delay the better chance for optimizing timing – and the more accurate transient response you get. Working both as an acoustic tuned ‘spring’ for the drivers, as well as getting rid of reaction force (resonant) energy, the cabinet is an important part of the entire speaker system.
Even the layout of the grille pattern was subject to serious experimenting. There are no similar sized holes, the benefit being that the cloth stays silent on the grille itself. Multiple, identical holes would cause the cloth to vibrate on the grille as the airflow through each hole would be identical. These partitions as well as the internal bracing have been very carefully positioned within the EPICON 6.
TWEETER HYBRID TWEETER MODULE For a transparent and solid rendering of even the most subtle high frequency details the finest DALI hybrid tweeter module is employed in the EPICON series. A tweeter solution inherited from our high end EUPHONIA and HELICON series, but with a newly developed dome tweeter. The module consist of a 29 mm lightweight dome tweeter and a 10 x 55 mm ribbon tweeter. Working in unison, the soft dome tweeter and DALI A/S www.dali-speakers.
DOME Low resonance frequency, high power handling, and exceptional headroom for high sound pressure levels and extreme excursions are all characteristics of the oversized soft dome tweeter. It is rolled in carefully around 2.5 - 3.1 kHz, depending on the model. And the dome is allowed to operate up to its high frequency limit well beyond 20 kHz without being rolled off in the crossover.
WOOFER Since the introduction within the EUPHONIA series further refinement of wood fibre cones has been the target for numerous in-house experiments. The result of this development process is the latest generation of the woodfiber cones, including new cone impregnation process and a new postassembly coating.
LINEAR DRIVE MAGNET SYSTEM For years designing magnet systems has been a DALI specialty. For the EPICON series we decided to challenge the highest market standards and to take magnet system design further than ever before in order to reduce distortion generated from less than perfect magnet systems. New materials, new processes - and hundreds of hours of engineering were needed.
Force Factor While many people know about the importance of the right BxL product (force factor) to generate sufficient power for adequate sound pressure levels and (even more important) the desired electrical Q of the woofer (the BxL product influences the Qe in the power of two), little attention is often given to the potential improvements in a distortion reducing design.
Voice Coil Inductance Linearization EPICON 6 woofer 3 The output from the amplifier is a voltage swing, while the force generated in the motor system is a function of current. 2,5 Inductance [mH] 2 Thus, the impedance seen by the amplifier needs to be stable. However, in most magnet systems the voice coil inductance depends on the position of the voice coil (the cone excursion).
Current Immunity and Frequency Independence Two problems even more difficult to solve than the voice coil excursion dependency are: The modulations of the flux in the magnet gap, when current running through the voice coil windings generates new ‘competing’ flux in the magnet gap. The frequency dependency of the electrical and magnetic properties of the iron parts.
Physical properties of SMC The nature of the hysteresis (magnetization curves) in pure iron is often only considered to be like text-book illustrations. However, this idealized situation is only the case when the frequency approaches DC. 2 1.5 1 1 Flux Density [T] 1.5 0.5 0 -0.5 -0.5 -1.5 -1.5 -0.5 0 0.5 1 Field Strength [A/m] 1.5 1 1 Flux Density [T] 1.5 0 -0.5 -1.5 -0.5 0 0.5 Field Strength [A/m] 1 -2 1.5 x 10 -3 1.5 1 1 0 -0.5 -1.
SMC 200 Hz 10 Hz Iron The above illustrations shows the flux lines generated in the magnetically conductive parts of the magnet system (iron or SMC). Current linearity 10 In a standard iron-based magnet system, the current in the voice coil will modulate the flux in the magnet gap.
The SMC material used in the EPICON midranges and woofers offers exactly the right properties: Very high magnetic conductivity and very low electrical conductivity (approx. 1/10.000’s of iron). The SMC-version is significantly less influenced by the current in the voice coil, reducing the distortion from current generated flux variations accordingly. Simulation of inductance − EPICON 6 magnet system 1.8 1.6 1.4 1.2 1 0.8 0.6 0.4 0.
The Result of Linear Drive Magnet System Design While more expensive to build, significant improvements compared to former available loudspeaker motor designs have been developed and implemented in the EPICON woofer magnet system. We have chosen to name the design Linear Drive as the motor system is linear with respect to excursion, current and frequency. The reduction of distortion is both very clearly measurable and indeed audible.
SIGNAL PATH All EPICON speakers feature a dual set of terminals on the back, allowing for both bi-wiring and bi-amping. For single-wiring/amping the speakers come with a set of terminal links made from gold-plated cupper for maximum connectivity. The sturdy gold-plated terminals are DALI-designed. A design which has been applied and refined in our highend series over the last many years. They accept fork cable lugs, bare wire, and banana plugs.
The EPICON loudspeakers are capable of extremely detailed and precise reproduction of the signal generated by the amplifier. And, a better amplifier performance will most likely reveal new levels of the EPICON performance potential, we take great care in creating optimized working conditions of the amplifier. With exceptionally flat impedance across the audio spectrum, EPICON loudspeakers present an easy load to the amplifier for significantly reduced amplifier distortion.
A note from the chef… Adhering to DALI’s low-loss sound principle the crossover must be as simple as possible. Naturally this requires the best ‘raw material’, e.g. drivers and cabinet. In EPICON this is exactly what we have. And each component in the crossover has been handpicked for its specific abilities after hours and hours of measuring and listening. The crossover is hand-soldered for shortest distance and best contact point.
The EPICON speakers are all supplied with a detachable front grille to allow for flexibility in appearance. For a clean look, and for easy and secure mounting/dismounting of grilles, both the cabinet and the grille feature concealed neodymium magnets. With the grille in place the EPICON radiates powerful elegance, and without it clearly signals acoustic superiority. And all in a design which will last a lifetime.
Maintaining the transparency and level of detail was important in the development of the EPICON 8. Though larger than the rest, this speaker presents both micro- and macrodynamics with an authority which is hard to believe. A more complicated speaker in the development, but also a rewarding speaker which will never let you down. The dedicated midrange driver blends in seamlessly with both the hybrid tweeter module and the two woofers.
EPICON TECHNICAL SPECIFICATIONS EPICON 8 EPICON 6 EPICON 2 EPICON VOKAL 35-30.000 35-30.000 47-30.000 49-30.000 Sensitivity [2.83V/1m] [dB] 89.0 88.0 87.0 89.5 Nominal Impedance [ohms] 5 5 4 6 112 110 108 111 50-500 50 - 300 30-200 50-300 550/3.100/15.000 700/2.550/15.000 3.100 2.750/15.000 3+½-way 2½+½-way 2-way 2+½-way Frequency Range [+/- 3] dB [Hz] Maximum SPL [dB] Recommended Amp.
