Напольная акустика — PMC MB3 XBD-A

The MB3 XBD-A is a powered two-enclosure main monitor made by PMC, the UK company behind loudspeakers for studios and homes. It starts from the single-cabinet MB3-A, a three-way design with a 12 inch Radial bass driver, and adds a second enclosure below it given over entirely to low frequencies, with one more Radial unit. PMC aims the system at larger control rooms, and a matching low-profile MB3 XBD-C-A centre speaker exists for multichannel arrays.

Key specs that matter

Per side the system uses two PMC 310 mm (12 inch) Radial woofers, a hand-built 75 mm soft-dome midrange and a 34 mm soft-dome treble unit combined with an acoustic radiator, divided at 380 Hz and 3.8 kHz. Rated response runs from 20 Hz to 25 kHz, and maximum output is 129 dB at 1 m, against 126 dB for the single-cabinet MB3-A. PMC lists 3225 W per channel, made up of 275 W rms for the tweeter, 550 W rms for the midrange and 2400 W rms shared by the two bass sections. Each cabinet has its own transmission line of 3 m effective length. The input is AES3 digital at 24-bit and 96 kHz, input sensitivity is adjustable from +4 to +20 dBu, and balanced input impedance is 20 kOhm. Stacked, the pair of cabinets is 1740 mm high, 380 mm wide and 535 mm deep, and one complete speaker weighs 88 kg.

Engineering and use context

Against the MB3-A the extra bass cabinet brings 3 dB more headroom below the lower crossover point, and PMC states that it lets bigger rooms be driven with a smoother frequency response. The two enclosures can be freestanding or built into soffits, and they can sit one above the other or side by side, which gives studio designers some freedom over layout. Because the response already extends into the deepest bass, PMC does not treat dedicated subwoofers as a requirement for this system. Low-frequency loading follows PMC's ATL principle, in which the rear output of each woofer travels down a damped internal line before emerging from a vent. The product carries a 20-year warranty if it is registered within 10 days of purchase.

Pairing

As the amplification and crossover are supplied as part of the system, the MB3 XBD-A connects to a mixing console, monitor controller or digital audio interface with an AES3 output. The adjustable input sensitivity helps match the reference level of the studio signal chain.

Alternatives

The PMC BB6 XBD-A is the larger twin-cabinet active tower in the same studio line, using two 15 inch Radial woofers and reaching 131 dB.