FBT X-Sub 115SA Aktiv subwoofer

Active 15" Subwoofer for Deep Bass Extension

To extend low-frequency reach in PA systems, you need a subwoofer that supplies both power and seamless integration with full-range tops. The FBT X-Sub 115SA is an active bass-reflex design that pairs perfectly with the X LITE and X PRO series, but also performs with any powered speaker. Outfitted with a 15-inch woofer, 3-inch voice coil, and a 1200W Class D amplifier, this model delivers up to 135 dB SPL from 42 Hz to 120 Hz. Connection is straightforward via stereo combo inputs, link outputs, and high-pass filtered XLR sends for use in portable or installed sound setups.

Integrated DSP with Configurable Crossover Presets

Onboard DSP offers four quick-access presets, removing the need for external processing — choose a flat response or engage high-pass filters at 80 Hz or 120 Hz to suit your satellites. You can use the phase reverse switch (0°/180°) for alignment with top speakers, and protection/limiter LEDs prevent overload during high-demand use.

Low-Frequency Output & Amplifier Headroom

For robust bass, the synergy between woofer size, coil diameter, and amplifier output is essential.

• Woofer: 15" with 3" voice coil — manages continuous high-power signals without compression
• Class D amplifier provides 1200 W output, minimizing heat during extended sets
• Maximum SPL: 135 dB — enough headroom for medium venues without risk of clipping

Signal Routing & Crossover Flexibility

Proper routing of bass and mid-high signals preserves system clarity and prevents frequency overlap.

• Frequency Range: 42 Hz – 120 Hz (-6 dB) — reaches fundamental bass below most full-range speaker cutoffs
• Crossover Selection: 80 Hz or 120 Hz — matches typical satellite low-cuts without needing outboard processors
• Stereo combo XLR/Jack inputs, loop-through, and HP-filtered XLR sends allow daisy-chaining or direct satellite feeds

Tour-Ready Construction and Transport

Constant loading, stacking, and moving are a fact of life for PA subwoofers. Birch plywood and ergonomic hardware are crucial for real-world use.

• Enclosure: 15 mm birch plywood, scratch-resistant black finish — protects against transport wear and reduces cabinet resonance
• Weighs 30.3 kg and features two ergonomic aluminum handles for one-person lifting
• Deployment: M20 stand adapter, optional 100 mm castors — mount a satellite above or roll the cabinet between venues with ease