Subwoofer Hertz MP 250 D2.3 PRO

Subwoofer Hertz MP 250 D2.3 PRO

Excellent performance in compact sizes, that's the goal of Mille PRO subwoofers. The MP 250 D2.3 PRO membrane is produced by pressing paper pulp and injecting mineral powders, the same construction technique used for the Legend range. The profile of the V-cone® oscillating diaphragm increases stiffness, allowing it to function like a piston. The hinge is made of high-purity IIR-butyl rubber. Similar to the ML 2000.3 and ML 2500.3, the Mille PRO subwoofers are built with "Boundary Free Surround" technology, which allows for a larger diaphragm area with a uniform diameter and creates a higher sound pressure. The compact 6-beam aluminum alloy anti-resonance basket is the same as the top model ML 2500.3 and contributes to the mechanical damping of the subwoofer, which is completely transparent to the sound. The 65mm 4-layer coil is wound in TIL-P, ensuring high linear displacement. 2 + 2 Ω impedance improves versatility to match any amplifier system. The air cooling and decompression system eliminates the need for a center hole on the bottom plate with three advantages:

• Better thermal inertia to ensure low operating temperatures during musical transitions.
• Maximizing the magnetic field induced on a coil with the same overall magnet dimensions. Due to the larger amount of iron in the pole, the probability of magnetic saturation is reduced using the maximum flux density generated by the magnet.
• Possibility of installing the subwoofer directly on the wall of the box with full use of its minimal dimensions. A damping rubber disc (supplied with the product) protects the subwoofer from damage and allows air exchange for the 10 ventilation holes on the bottom.

Holes behind the coil winding and 10 vents on the bottom plate of the subwoofer ensure greater air exchange to the inner layers of the coil and work in conjunction with an innovative mounting system. This forces air through the air gap to keep the coil operating temperature low, even with the most extreme music genres. The terminal uses solid pressure connectors with a housing that allows cables up to 8 AWG to provide very low line resistance in low impedance (1Ω) configurations.

The main features of the Hertz MP 250 D2.3 PRO subwoofer

• Ergonomic compact design, specially developed for closed enclosures starting with a volume of 17 l.
• CCAW, 65mm (2.5") four-layer voice coil, capable of handling 1200W of music.
• 2 + 2 Ω impedance improves versatility.
• Voice coil wound on TIL-P material with vent holes behind the winding.
• Efficient heat dissipation with a high Qms factor.
• Exponential V-cone® membrane with optimized geometry for high membrane stiffness and strong resistance to deformation even at maximum displacements.
• Mineral injected paper membrane for excellent stiffness.
• Aluminum alloy basket.
• 6-spoke construction and built-in vents under the spider.
• Connection terminal block for cables up to 8 AWG to provide very low resistance in low impedance configurations.
• The plastic cover prevents any accidental shorting.

Catalog number	MP 250 D2.3 PRO
Brand	Hertz
Links	Official web presentation
RMS powerThe RMS power of the subwoofer is the constant power of continuous use of the subwoofer. If the power is exceeded for a longer period of time, irreversible damage may occur, or to burn out the voice coil of the subwoofer.	600 W
Max. (maximum performancePeak performance , which the subwoofer can play momentarily (approx. 0.5 s), for example when hitting drums in a song. If the maximum power is exceeded, damage can quickly occur, or to burn out the voice coil of the subwoofer.	1200 W
Sensitivity (SPL 2.83V/1m)Subwoofer sensitivity or efficiency. The sensitivity of the subwoofer is given in decibels (dB) and, in simple terms, means that the higher the value, the lower the demands on the power of the amplifier. This is a de facto rating of how a subwoofer converts watts to sound. Sensitivity ratings are in noise level measured at 1 meter from the subwoofer using 1 W (watt of power) or using 2.83 volts at the source at 1 meter. A higher decibel level means the subwoofer is louder with less power. For every 3 dB increase in sensitivity, the subwoofer requires half the power to reproduce the same volume. For example, if an 88 dB subwoofer needs 300 Watts to produce a certain volume, then a subwoofer with 91 dB sensitivity needs only 150 Watts to reach the same efficiency.	83.5 dB
ImpedanceImpedance - measurement of electrical resistance. When buying a subwoofer, it is very important that everyone make sure that the impedance matches the amplifier that you are connecting to it. For subwoofers with a double voice coil, we recommend following the information in the advice center! Example: A 2 Ohm subwoofer cannot be connected to an amplifier that is only stable up to 4 Ohms. A 4 Ohm subwoofer can easily be used on an amplifier that is stable up to 2 Ohms. Connecting a 4 Ohm subwoofer to an amplifier that is stable up to 4 Ohms also without problems. The most common subwoofer impedance is 4 Ohm.	2 + 2 Ω
Subwoofer diameterThe diameter of the subwoofer is indicated on the screw holes. The overall outer diameter of the subwoofer is usually 1-2 cm wider, depending on the size category of the subwoofer. For a 30 cm subwoofer, the outer diameter incl. protective rubber 31.8 cm and in the 25 cm subwoofer it is 26.5 cm incl. protective rubbers.	250mm (10")
Subwoofer mounting depthThe mounting depth of the subwoofer is measured from the bottom edge of the magnet to the bottom edge of the subwoofer's metal or cast basket.	141 mm
Fs - resonant frequencyFs - is the lower resonant frequency. This parameter is the de facto free air resonant frequency of the subwoofer. Simply put, it is the point at which the weight of the subwoofer's moving parts equals the force of the subwoofer's suspension while it is in motion. If you've ever seen a piece of string start to hum uncontrollably in the wind, you've seen the effect of reaching a resonant frequency. The weight of the moving parts and the stiffness of the suspension (surround and spider) are key elements that affect the resonant frequency. As a general rule, a lower Fs indicates a subwoofer that would be better at reproducing low frequencies than a subwoofer with a higher Fs. However, this is not always the case, as other important parameters of the subwoofer also enter the resulting sound.	30 Hz
Vas - equivalent volume of airVas - represents the volume of air that, when compressed per cubic meter, acts with the same force as compliance (CMS), suspension in a certain subwoofer. Vas is one of the most complicated parameters to measure, as changes in air pressure are affected by conditions of relative humidity and temperature. Another way to describe what VAS is: try using a subwoofer and find a baffle that is the right size to return the air with the same stiffness to the same resonance. The size of this box is equal to you. There are, of course, other parameters, but they are not so necessary for the exact calculation of the enclosure. Resonance frequency and Q-parameter values are also important when building enclosures.	25 l
Xmax + -Xmax - the maximum deflection of the subwoofer diaphragm in one direction – it is not a sum, or an abbreviation for the maximum linear deflection. The subwoofer output becomes non-linear as the voice coil begins to leave the magnetic gap.	17
QesElectrical Q-factor of driver is the electrical quality factor (electrical damping). If the subwoofer coil moves in a magnetic field, it generates its own current that counteracts its movement. Qes is a dimensionless parameter and the lower the number, the higher the generated current and the more damped the coil movement, thus reducing the total current flowing through the coil, the deflection and the sensitivity around the fs resonance. It varies in values from 0.08 to 0.6, in the extremes, for ordinary universal converters, even 20. Subwoofers with too low a Qes value, a very damped system, are not suitable for certain types of enclosures.	0.6
QmsMechanical Q-factor of driver is a mechanical factor of quality (mechanical damping). These are mechanical losses affecting (damping) the movement of the subwoofer membrane. Qms is a dimensionless parameter and the higher the number, the smaller the losses, i.e. the deviation and sensitivity in the lower band is also higher, it ranges around 0.4 - 25.	5.92
QtsTotal Q-factor of driver is a total quality factor, it includes both parameters Qes and Qms (electrical Qes and mechanical Qms). It varies in values from approx. 0.08 to 0.6, exceptionally up to 3. The Qts of the subwoofer is calculated in the same way as, for example, a pair of parallel resistors, so the result is decisively influenced by a smaller value that cannot be exceeded, which is usually Qes.	0.54
Subwoofer voice coil diameterThe larger the diameter of the voice coil, the more load capacity the subwoofer has, in layman's terms.	65 mm
MassSubwoofer weight in kilograms. The weight is usually given net, i.e. without packaging.	8.2 kg