PROEL introduces the S Series, a new range of compact and powerful sub-woofers designed to complement PROEL full-range speakers. The variety of size, power and SPL offered by the four active S models provides, at an unbeatable price point, the perfect low extension solution for any speaker model available in the PROEL range. All the S models feature high-excursion woofers in a Hybrid Band Pass configuration (HBP). This innovative design provides a higher efficiency compared to direct radiation sub-woofers and, in addition, guarantees a much better coupling of the tuning ducts with the external air, reducing the distortion and the air turbulence, for a more defined sound and deep and punchy lows. The new CLASS D amplifier modules with SMPS (Switch Mode Power Supply) can generate a massive amount of continuous power in a compact, lightweight and reliable package. All the modules include a STEREO pre-amp section, 24dB/oct. crossover filters with selectable frequency and PHASE reverse switch. The cabinets are built with 15/18mm plywood and finished with extra-durable polyurethane paint. They feature two flush handles and four sturdy 75mm wheels for an easy transport (S15 and S18 only).