ELAC 250 4Pi (1985) - German Engineering

24 September 2022

ELAC 250 4Pi (1985) - German Engineering

The ELAC 250-4Pi loudspeaker system was designed as a 4-way unit. Each of the loudspeaker chassis used only has to transmit the frequency range in which it works best. The playback quality is clearly audibly better because the amplitude frequency response (the evenly loud playback of all frequencies from the deepest bass to the highest treble), the phase behavior and the directional characterteristics are optimal. The - compared to conventional three-way systems - smaller frequency band, which is transmitted by the speaker chassis, eliminates the otherwise frequently heard sound discoloration in the mid-range, for example, and the sound radiation is more even, less directed.

The low frequencies are transmitted up to around 550 Hz by four small special low-frequency drivers. The comparatively small cones are lighter and more stable than those with a larger diameter. The lower dead weight and the powerful coating due to the four large magnets result in an optimal power/mass ratio. Great acceleration is essential for the realistic bass reproduction and therefore no problem. The unintentionally precise impulse reproduction has an overwhelming effect. A total of four loudspeaker chassis - all special developments for the 250-4Pi - work in parallel, falling through the transmission line. The bass systems and the transmission line were designed in such a way that the lowest frequencies down to 20 Hz can still be reproduced cleanly.

The midrange, which is so important for the natural sound image, is transmitted by two fabric dome speakers. Frequencies from 550 to 1450 Hz are reproduced by the 80(!) mm dome system. It can transmit this frequency range precisely and without distortion. The MT 25 high-midrange system, a special ELAC development, transmits the frequency range between 1450 and 4000 Hz.

For the reproduction of the high tones from 4000 Hz, the 4Pi uses a technology newly developed by ELAC engineers and patented together with the Dutch group Bakker/van den Hul is used for the first time. Instead of the usual dome or cone diaphragms, a cylindrical aluminum strip that is only 5 thousandths of a millimeter (5 μm) thin is used. This extremely light cone has unmistakable advantages: an exceptional impulse reproduction is achieved thanks to the low surface weight. Only sound-radiating parts are moved in this innovative tweeter system. There are no longer any drive coils, which ignite the oscillating mass in conventional tweeter systems and thus round off the finest impulses during playback. Two powerful toroidal magnets arranged above and below the cylindrical ribbon holder generate the force field to move the aluminum ribbon. With the ELAC 4Pi technology, high frequencies are emitted evenly in the room, a basic requirement for homogeneous sound propagation in the listening room.

High quality crossover network. The 250-4Pi contains only selected components. The high-quality air coils are manufactured by ELAC itself - only then can the exact optimum values be maintained within the narrow tolerances specified for this high-quality speaker system. Only film capacitors are used so that the first-class sound impression is retained for years to come. They guarantee long-term stability of their physical parameters. Even the influence of the connection cables on the sound was taken into account: oxygen-free copper cables connect the chassis to the network, the network to the connection terminal.