The UK's leading Integrator and Equipment
Installer for the Digital Cinema Industry


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Founded over four decades ago, QSC Audio Products, LLC, is a globally recognized leader in the design and manufacture of professional audio system solutions. Sound Associates have been specifying and installing QSC amplifiers for use in cinemas large and small for many years and now with Q-Sys we continue to deliver high quality cinema sound.

QSC introduced a full range of cinema speakers and Sound Associates is proud to have carried out all of the UK installations of their stage, sub-bass and surround speakers. The range now includes digital signal processing (DSP) and, again, Sound Associates have carried out numerous installations, both here in the UK as well as overseas.

In 2016 QCS acquired Ultra-Stereo Labs, Inc. (USL) allowing them to offer an industry-leading porfolio of sound processing solutions for the motion picture exhibition industry.


Part of the DCS Digital Cinema Speaker Series, QSC's SB-15121 subwoofer offers the highest performance available for cinema subwoofer applications. It is designed for use in premiere cinemas and post-production applications where the ultimate in performance is required.

The massive 21"" low-frequency transducer features a 6"" diameter voice coil in a vented, neodymium magnet structure that is designed to dissipate extreme amounts of heat and allow for excursion that is double that of typical 18"" transducers. This ensures cool operation, even at high power levels, increases driver lifespan and decreases power compression at high drive levels.

The large, ported enclosure ensures response to the lowest audible frequency for bass that you can not only hear but also feel. The enclosure is constructed of high quality, heavily braced MDF Panels. Large, fully radiused ports ensure smooth airflow, especially at higher drive levels. This prevents potentially audible port turbulence noise. Both internal and external port openings are flared.

With symmetrical port loading, the bass ports are evenly spaced around the transducer, making internal pressure more uniform across the back surface of the woofer. This prevents the cone from being displaced to one side or another by unbalanced air pressure, reducing the chance of driving the voice coil out of the center of the gap at high drive levels.


  • 1500 W, 21"" transducer.
  • Frequency range extends to below 25 Hz without the need for B6 EQ filters.
  • DCP, DCM and SF-3 signal processors optionally available.

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