Floorstanding loudspeakers — Brodmann JB 205

The JB 205 is the tallest model of the Joseph Brodmann series from Brodmann Acoustics of Vienna, Austria, a passive floorstanding loudspeaker built around the company's patented Horn Resonator enclosure. It stands just over two metres tall and uses side-mounted drivers to excite wooden panels in the cabinet, a principle Brodmann developed from piano-building practice.

Key specs that matter

Brodmann lists a range of 20 Hz to 29,000 Hz within 3 dB. The acoustic crossover sits at 130 Hz with a slope of 4.5 dB per octave, and the electrical crossover at 1.6 kHz with 5.7 dB per octave. Sensitivity is stated as 91 dB from 0.9 W. Nominal load is 480 W and music load 1000 W, with a nominal impedance of 3 ohm. The cabinet measures 2051 x 454 x 330 mm, height first, and the speaker weighs 75 kg.

Engineering and use context

The driver layout is unusual for a passive tower. Four front-mounted tweeters work with ten woofer and midrange drivers, and four active acoustic panels provide a combined radiating area of 1.41 m2. The grilles are designed to scatter sound. The enclosure is the second generation of the Horn Resonator, and the Acoustic SoundBoards are thin boards that would normally stay passive but are set into motion by the side-mounted woofer and midrange units, so they act as an additional large membrane. Tensioning screws allow the amplitude of these boards to be fine tuned. The cabinet contains no damping material, which is part of the design concept rather than an omission. Brodmann also lists an acoustic active crossover, its Fundamental Tweeter system and a feature it calls The Pure Voice among the technologies used in this model. A later JB 205 MkII was offered together with an Active Bass Tower, a separate DSP-controlled cabinet rated at 1500 W RMS that covers 16 Hz to 120 Hz within 3 dB with an adjustable crossover between 25 Hz and 95 Hz. That tower is 1650 mm high, 300 mm wide and 450 mm deep and weighs 90 kg. The MkII itself is listed at 48 cm deep.

Pairing

The nominal load is low, so the amplifier has to deliver substantial current into difficult impedances. Solid-state designs with stable low-impedance operation fit better than small valve amplifiers, even though the sensitivity figure means moderate power reaches normal levels. Given the height of the cabinet and the side-firing drivers, a spacious room well above 20 m2 suits it best.

Alternatives

The Brodmann JB 175 is the other floorstanding model Brodmann lists within its Joseph Brodmann series.