Напольная акустика — Acapella SPHÄRON EXCALIBUR

The Sphäron Excalibur is a four-way horn loudspeaker system from Acapella Audio Arts of Duisburg, Germany. Each pair is made to order to the customer's specification. The base price starts at about EUR 560,000 per pair, rising to about EUR 620,000 per pair with the integrated mono amplifiers.

Key specs that matter

Every channel combines an ion tweeter fitted with a horn, a midrange driver on a spherical horn of roughly 60 cm diameter, a 254 mm low-midrange driver on a spherical horn of about one metre, and four 460 mm cone woofers. The crossover points lie at about 5 to 7 kHz, 500 Hz and 100 Hz. Acapella quotes a range of 15 Hz to 40 kHz, an efficiency of about 103 to 107 dB at 1 W and 1 m, and a nominal impedance of 8 ohm. Each speaker stands 2.3 m tall on a footprint of 1.7 x 1.7 m and weighs roughly 1.2 to 1.3 tonnes, and the recommended room size starts at about 40 m2.

Engineering and use context

Instead of a membrane, the tweeter relies on a plasma flame held by high voltage and modulated by the music signal, which lets it work from around 5 kHz up to about 50 kHz. The two spherical horns cover the range above the woofers up to the tweeter, so the cone drivers behind them see only a limited slice of the spectrum. Below the lowest crossover point the work passes to four bass reflex modules per side, each carrying one woofer in its own enclosure of about 200 kg, stacked vertically into a column taller than a person. The frequency division is passive, with no active electronics in the signal path between the bands. Earlier Sphäron models relied on a bass horn that needed around 12 m2 of floor area, and the reflex column of the Excalibur removes that requirement. Customers choose between black or white acrylic and wood veneers for the cabinets, and the horns can be painted in any automotive or RAL colour.

Pairing

Acapella offers matching mono amplifiers designed by Lorenz Martensen, derived from the LaMusika integrated amplifier and fed by three-phase mains. They are mounted inside the tweeter enclosure on a special rope suspension. Asked about their output, the company stated only that it is fully sufficient and gave no figure. With its very high efficiency, the system can also be driven by low-powered amplifiers, and the maker has shown it with its own The Audio One streaming server and a DAC and preamplifier of its own design.

Alternatives

The Acapella Triolon Excalibur is another Acapella floorstanding horn system and sits below the Sphäron in size.