RCF SUB 708-AS MK3 18" Live Sound Portable Active Subwoofer 1400W Stereo Crossover

RCF SUB 708-AS MK3 18" Live Sound Portable Active Subwoofer 1400W Stereo Crossover


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RCF SUB 708-AS MK3 18" Portable Active Subwoofer 1400 Watts For Live Sound with Stereo Crossover


  • 1400 Watt Class-D Amplifier

  • 18” Woofer, bass reflex housing

  • Stereo Crossover

  • Switchable Crossover Frequencies

  • Polarity-reverse switch

  • Electronic equalization, soft limiter and protection

  • Stereo XLR input, Stereo XLR signal output

  • Bass Motion Control excursion management

The SUB 708-AS mk3 is a portable 18" high-power active subwoofer for live sound applications. It features a state-of-the-art transducer with a high-power ceramic magnetic circuit and a powerful Class-D amplifier that delivers sound pressure levels up to 133 dB with exceptional headroom. 

  • Designed as the ideal complement for 8" or 10" loudspeakers, it provides outstanding performance in any application. Rear panel controls include volume, EQ, polarity, and crossover frequency selection. 
  • The rugged all-wood cabinet with scratch-resistant polyurea coating makes it durable, easy to carry and install securely. With its versatility, sound quality, and high power output, the SUB 708-AS MK3 is perfect for small to mid-sized venues and portable applications.

Legendary subwoofers

  • RCF subwoofers are the first choice of many sound engineers, thanks to the very high SPL levels at very low frequencies, small dimensions compared to the competitors, self-powered design, long-term reliability, and impressive size/weight to SPL output ratio. Your crowd will be able to live an engaging immersive experience in both live sound or DJing applications.

Power That Moves

  • RCF's improvements in transducer design make them stronger and more powerful so the amplifier follows the evolution. With 1400W peak power, the Class-D amplifier manages extreme sound pressure levels with an ultra-fast attack, realistic transient response, and very low heat loss.
  • The speaker design is energy-efficient so there's no need for a cooling fan. The amplifier is attached to a solid aluminum heat exchanger in the rear of the cabinet with no moving parts.
  • The stereo input circuit with crossover features a new low distortion design with an advanced safety limiter, maintaining the true character of the input signal at all levels. RCF amplifiers are designed according to EN62368-1 for maximum safety and present a Switch Mode Power Supply section joining high-efficiency with minimum weight.

SUB 7 Series subwoofers can be configured from the rear panel, and features a full set of commands:

  • X-OVER PRESET 80Hz/120Hz



Bass Motion Control

  • When searching for an extended bass with enhanced performance, RCF engineers found a way to remove the high-pass filter, replacing it with a forward-thinking approach. Introducing BMC (Bass Motion Control), the newly advanced woofer excursion management feature. The speaker equipped with BMC can handle the lowest audible frequencies without affecting the woofer stability, with extended linearity and better sound integrity.

  • The BMC method works by creating a complete map of the dynamic behavior of the woofer, to generate a custom algorithm that only limits over-excursions. This gives total freedom of signal reproduction to the transducer. When high-pass filters normally protect the woofer motion from becoming destructive but change the phase behavior, the new BMC algorithm breaks conventional rules.

Tour-Ready Workhorse

  • The subwoofer is suitable for a wide range of live sound applications. The rugged all-plywood cabinet is easy to carry and stack, due to its light-weight. All are equipped with ergonomic handles with rubber grips for easy set-up and tear down. The M20 threaded pole mount on the top allows the cabinet to support speakers with a pole mount.
  • The heavy-duty polyurea coating, the powder-coated metal grille, and the rugged structure of the cabinet withstand long-term use and transportation. Separate housing for the amplifier guarantees component efficiency and reliability. An acoustically transparent sound foam backing on the inside of the grille ensures protection from dust and humidity. With its frontal vented ports, the subwoofer can also be used in recessed spaces.


Acoustical specifications

  • Frequency Response: 35 Hz ÷ 120 Hz

  • Max SPL @ 1m: 133 dB

  • Transducers

  • Woofer: 18'', 3.0'' v.c

  • Input/Output section

  • Input signal: bal/unbal

  • Input connectors: XLR

  • Output connectors: XLR

  • Input sensitivity: -2 dBu/+4 dBu

Processor section

  • Hi-Pass Frequencies: 110 Hz

  • Low-Pass Frequencies: 80 Hz

  • Protections: Thermal, RMS

  • Limiter: Soft Limiter

  • Controls: Volume, EQ, Phase, Xover

  • Power section

  • Total Power: 1400 W Peak, 700 W RMS

  • Low frequencies: 1400 W Peak, 700 W RMS

Cooling: Convection

  • Connections: VDE

  • Standard compliance

  • Safety agency: CE compliant

  • Physical specifications

  • Handles: One each side

  • Pole mount/Cap: Yes

  • Color: Black


  • Height: 693 mm / 27.28 inches

  • Width: 505 mm / 19.88 inches

  • Depth: 685 mm / 26.97 inches

  • Weight: 40 kg / 88.18 lbs

Shipping information

  • Package Height: 735 mm / 28.94 inches

  • Package Width: 565 mm / 22.24 inches

  • Package Depth: 745 mm / 29.33 inches

  • Package Weight: 45 kg / 99.21 lbs

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