The SP21E is a compact self-powered high SPL sublow system. The cabinet is constructed of a rigid, multilayer birch ply reinforced with multiple bracing and finished with a sturdy coating.

Cabinet dimensions are optimised for international trucksize. Ergonomical grippoint layout, Nano Armor polyurethane coating and additional corner protection with muliple slide bars facilitate easy transport. Protective slidebars facilitate locked stacking of more cabinets. Polemounting can be done
standing or flat. The SP21E will endow any of F.O.H. system with a rock solid foundation in the lowest audible octaves.

The SALC (Single Audio-logic Level Control) speaker management is a proprietary RMS based gain riding circuit which maintains the tonal balance of the sound as perceived by the human ear and protects the drivers from over excursion or overheating.. A recessed switch facilitates Sound Projects standard* or free external lowpass selection.

To match the desired cabinet dimensions and to obtain maximum efficiency, state-of-the-art computer aided modelling techniques and acoustic calculation programs are used to precisely indicate the manifold reinforcing ribs and port tuning.
*60Hz @ 24dB Butterworth