The ST-215 is a compact touring subwoofer, and whilst it is designed to be mechanically and acoustically compatible with the new HALO-B system, it is a standalone product in its own right and can be used to support any EM Acoustics product – either in a flown or ground stack configuration.

The compact enclosure houses a pair of 4” voice coil, 15” (381mm) neodymium drive units, in an optimally-tuned reflex design with a single low-velocity port to minimise distortion generated by turbulence. The drive units’ high motor strength gives the ST-215 excellent transient response, and the moving area of the two high-excursion 15” drive units generate significant low frequency extension and overall subwoofer output. The enclosure is symmetrical, so in both flown and ground stacked configurations one enclosure in every three can be rotated to point physically backwards to create a cardioid array. Such arrays offer exceptional low frequency directivity control and significantly reduce the energy radiating to the rear of the subwoofers.

The robust enclosure is constructed from premium 18mm (¾”) multi-laminate Birch plywood – rebated, screwed and glued together for maximum strength. The enclosure is finished in our 3-step polyurethane coating, which as well as being far tougher than conventional water-based paints used on other products offers the ST-215 a significant level of weather resistance without any further treatment. To make best use of this weather resistance the robust grille and all fixings are stainless steel and the drive units are weather protected, meaning the ST- 215 is ready for outdoor use straight out of the box.

The flying hardware has been built with touring flexibility and reliability in mind. The ST-215 uses a 4-point system, and all rigging components retract flush for transit and ground stack use. Using the FG-HALO-B master flying grid, the ST-215 is mechanically compatible with HALO-B systems or can be flown as a stand alone array. Ultra-high tensile steel parts form the core of the 4-point system, meaning arrays of up to 9 elements can be safely assembled with above-regulation safety factors.

The mechanical package is completed by a mesh-backed stainless steel grille, eight recessed bar handles (four per side), protective stacking runners and mating recesses, an M20 threaded pole adapter and attachment points for the optional castors on the rear.

The ST-215 requires a single amplifier channel and and an active crossover to function correctly – as such it is recommended to be used with the DQ10 or DQ20 advanced system amplifiers. Using these amplifiers a maximum of eight ST-215 subwoofers could be driven from a single DQ20 amplifier. For cardioid arrays, separate amplifier channels are required for the rear-firing subwoofer(s) due to the different processing needed.

Optional accessories include castor sets, multi-enclosure touring wheelcarts, flying grids and padded covers for both single enclosures and multi-enclosure carts