MPS 250 S4 4 Ohm Single Voice Coil

Mille PRO shallow subwoofers have been designed to achieve exceptional performance even when there is very little space available to install the subwoofer box.

Extreme dynamics, unlimited power handling, realistic sound stage

Mille PRO Shallow Subwoofer

MPS 250 S4 is optimized to work in ultra-compact sealed boxes starting from only 14 Lt (0.49 Cf). A typical example is a subwoofer enclosure under the rear bench of pickup trucks, where the space - and the height - are limited.

Mille PRO subwoofer have a depth/performance ratio never achieved before thanks to the impressive cone excursion capacity which is 20% higher than a traditional design.

This exceptional target has been achieved thanks to the ingenious suspension group design featuring a dedicated support structure for spider and coil. This solution has allowed to move the magnetic group inwards, reducing the depth and at the same time maximizing cone linear excursion.

500 W continuous power handling is an incredible result for such a compact subwoofer. To accomplish this ambitious goal, the Hertz R&D has developed the proprietary AIR (Air Intercooling Revolution) technology, optimizing the fluid dynamics of the inner acoustic structure and the magnetic group to minimize the internal compression of air and maximize cooling capacity. The 6 layers, 1.5 in. (38 mm) voice-coil with cooling openings on the former contributes to the thermal stability of the subwoofer, making MPS subs ready to face to most demanding high-spl listening session.

The design of the magnetic unit has been FEM simulated to maximize force factor (BxL) symmetry and thus obtain an optimal linearity even at high excursions, perfectly controlling the inductance modulation.

Pole piece geometry has been optimized using a breakthrough simulation model that allowed improving unit force factor.

Hertz R&D also focused on modeling the cone/enclosure behavior: inside a sealed box, air behaves like a spring – a non-linear suspension – whose effect must be compensated to obtain a system as linear as possible at high excursions.

• Size mm (in.)    250 (10)
• Power Handling - Continuous W    500
• Power Handling - Peak W    1000
• Impedance Ohm    4
• Depth mm (in.)    82,6 (3.25)
• Voice Coil Type    single
• No Filter Component    Subwoofers
• Voice Coil Ø    38 (1.5)
• Frequency Response Hz    25 - 400
• Magnet size D x d x h mm (in.)    134 x 55 x 36 (6.28 x 2.17 x 1.42)
• Weight of one component kg (lb.)    5,11 (11.27)
• Magnet    High density flux ferrite
• Cone    Polypropylene
• Xmech mm (in.)    20 (0.79)

• Hertz MPS 250 S4 
• Grille