Hertz Mille Pro MPS 250 S4 Sub 10" 25cm Shallow Car Subwoofer 4 Ohm 500w RMS

The Hertz Mille Pro MPS 250 S4 is a 10-inch (25cm) shallow car subwoofer from the Hertz Mille Pro range, rated at 500W RMS / 1000W peak with a single 4-ohm voice coil and an 82.6mm mounting depth.

Key specifications

• Size: 250mm (10")
• Power handling: 500W continuous / 1000W peak
• Impedance: 4 ohms, single voice coil
• Mounting depth: 82.6mm (3.25")
• Frequency response: 25Hz – 400Hz
• Voice coil: 38mm (1.5"), 6 layers
• Sealed box volume: from 14 litres (0.49 cu ft)
• Xmech: 20mm (0.79")
• Cone: polypropylene

MPS 250 S4 4 Ohm Single Voice Coil

The MPS 250 S4 is optimised for ultra-compact sealed boxes from just 14 litres (0.49 cu ft) — ideal for installations such as under the rear bench of pickup trucks where both space and height are restricted.

Mille Pro shallow subwoofers deliver strong depth-to-performance ratios thanks to high cone excursion capacity. This is achieved through a dedicated suspension structure for the spider and coil that allows the magnetic group to move inwards, reducing overall depth while maximising linear excursion.

500W continuous power handling is made possible by Hertz's proprietary AIR (Air Intercooling Revolution) technology, which optimises fluid dynamics within the internal acoustic structure and magnetic group to reduce air compression and maximise cooling. The 6-layer, 38mm (1.5") voice coil features cooling openings on the former to maintain thermal stability during high-SPL use.

The magnetic unit has been FEM simulated to maximise force factor (BxL) symmetry, ensuring optimal linearity at high excursions and controlling inductance modulation. Pole piece geometry has been refined using a dedicated simulation model to further improve the unit force factor.

Hertz R&D also modelled cone and enclosure behaviour to account for the non-linear spring effect of air inside a sealed box, keeping the system as linear as possible at high excursions.