Pioneer’s SLIM251S4 is an extremely compact shallow-mount subwoofer packaged into a single slim, bass reflex subwoofer box, pushing out a maximum power output of 800 Watts.

Air Suspension System
In order to create a subwoofer that is three and a quarter inches deep, Pioneer had to develop revolutionary subwoofer technology. A traditional subwoofer uses the spider design to keep the voice coil of the speaker aligned while it moves. This type of set-up can become soft over time degrading the subwoofer’s performance. Pioneer created a patent-pending air suspension system that locks air between a main cone and a drive cone.

The cones move together in unison, with the locked-in air behaving like a spring. The dual-cone structure is a spider-less design that maintains better sound linearity, and reliability even after many of hours of hard useThe pressure from the trapped air results in a consistent bass response across a wide frequency range. The result is a tight, precise movement with powerful and clean bass output.

3-Layer Interwoven Radial Surround
The shallow subwoofer incorporates an innovative woven cloth reinforced radial urethane surround for improved power handling, reduced distortion, improved durability, and louder, more controlled bass. The surround is constructed of three layers — two of urethane and one of interwoven cloth. The interwoven cloth distributes strength throughout the surround material and improving its high power capability.

The result is an extremely durable and resilient surround that resists puckering, even under intense power conditions.Unlike traditional surrounds that use a single arch shape design, the Pioneer Shallow Subwoofer utilizes a patent-pending M-shape surround that provides superior sound linearity.

M-Shaped Surround
The M-shape surround also has a lower height, and a lower fc or tuning frequency. The lower fc threshold translates to better and longer performance at lower frequencies.

Angled Push Terminals
Traditional subwoofer terminals are mounted horizontally or vertically. These mounts force wires to be bent to fit which can be difficult if low-gauge high performance wires are used. The Pioneer shallow subwoofer’s patent-pending, angled push terminals make it easy to connect speaker wires. The straighter connection saves space and makes installation easier.

Fin-Shaped Basket
Traditional subwoofers push air downward. This creates a “loading effect” or area of pressure underneath the speaker which hampers performance and responsiveness. The rear of the powerful and slim Pioneer shallow subwoofer is designed with specially-shaped fins that channel the airflow sideways instead of downward. Air is continuously pushed in a circular motion, eliminating the “loading effect” or unwanted pressure of air behind the cone.

TS-SW251 Specifications
• Size: 10”
• Woofer Cone Material: Composite IMPP using Interlaced Carbon Fibre and Glass Fibre
• Surround: Dual 3-Layer Fiber-Woven Radial Surround
• Voice Coil: 4-Layer
• Voice Coil Wire: Copper Round
• Voice Coil Bobbin: FQG
• Damper Ring: Heat Resistant ABS
• Magnet Construction: Strontium
• Gasket: 1-Piece, ABS
• Wire Terminals: Box Terminals
• Watts MAX. Music Power: 1000 Watts
• Watts Nominal Power Handling: 200 Watts
• Ohm Rating:  4 ohm
• Frequency Response: 20 Hz to 114 Hz
• Sensitivity: 89dB
• Dimensions: 278mm x 92mm (subwoofer only- excludes sub box)
• Mounting Depth: 78mm (subwoofer only – excludes sub box)

Enclosure Specifications
• Total Internal Volume: 10.08 litres
• Sealed Enclosure
• MDF Thickness: 16mm on all sides