L’Enceinte Bleue loudspeaker
The sound of a musical instrument is closely related to the acoustics and to the vibrations of its body whereas the panels of a high fidelity loudspeaker shall be totally free of acoustics and vibrations to accurately reproduce that sound. Moreover the emitted sound wave shall be phase coherently.
The Enceinte Bleue loudspeaker was designed in order to get rid of numerous problems like cabinet coloration and components distortions (multiple drivers with crossover and different technologies) : heavy and noble material i.e. granite, thick panels i.e. 30 mm, optimized damping i.e. woolen felt, and filterless virtual point source sound propagation.
The principle of a single full range transducer was favored. It is capable of reproducing the audible frequency spectrum without any crossover network unlike any multi-way loudspeaker. The cone was chosen very light for immediacy on transients that mainly form music. It is made of paper that is still the only material among which the versatility and the musicality remain unsurpassed in full range use, and the wide diameter improves the coupling with the ambient air so that the sound reproduction gets more weight and more presence.
The small volume of the Enceinte Bleue loudspeaker still meets the driver requirements. The intentional limited low end extension makes the loudspeaker remain spontaneous and thus reveals the slightest subtleties of the musical message. Moreover the harmonious proportions of the granite volume confer a unique and original aesthetics on the Enceinte Bleue loudspeaker which breaks the borderline between object and sculpture.
The enclosure is completely made of Belgian granite called Blue of the Hainaut. The relationship between width, height and depth was calculated so as to avoid any tonics (accumulation of resonances close to certain frequencies). It is fully handcrafted in France by the company Lith Audio. All 30 mm thick panels are cut out from the same granite patch and chamfered at 45° for perfect edge to edge sticking. Then the edges of the assembled enclosures are slightly chamfered for perfect finish. The granite is polished then waxed (two layers are applied). Even if the job is easy to describe the cutting, assembling and sticking processes turn out to be very complicated.
Because of the heavy weight of the granite and its brittleness to shocks and to scratches, every step requires a lot of care during all the manufacturing phase (use of heavy tools) which takes several days for one pair of enclosures. Every tuning port made of several stuck pieces of granite is polished by hand, a step requiring six hours of labour. The empty enclosure weight is 80 kg. Obviously this very sluggish mass creates an extremely stable mechanical reference for the driver which will reproduce a lot of details often unnoticed with traditional manufacturing loudspeakers.
Behaviour of the granite enclosure
The two Waterfall graphs here below i.e. on the left, open field measurement of the EMS LB12 speaker, on the right on-axis measurement at 1 m of the Enceinte Bleue, show the apathetic behavior of the granite enclosure which does not affect the signal delivered by the driver mounted in the enclosure. Nothing but transparency.