Subwoofer Hertz MPS 250 S2

Subwoofer Hertz MPS 250 S2

The Mille PRO flat subwoofers have been designed to deliver exceptional performance even when there is very little space available to install a subwoofer box. The MPS 250 subwoofer is optimized for working in ultra-compact closed enclosures with a volume of only 14 l. A typical example of installation is, for example, the double bottom of a trunk and other places with limited space. The Hertz Mille PRO flat subwoofers have an excellent ratio of mounting depth and performance thanks to an impressive coil capacity that is 20% larger than a traditional design. This exceptional goal was achieved thanks to the ingenious design of the suspension group with a dedicated support structure for the spider and coil. This solution made it possible to move the magnetic group inwards, reducing the depth and at the same time maximizing the linear deflection of the membrane.

The main features of the Hertz MPS 250 S2 subwoofer

• 10" subwoofer with a power of 500 W RMS and a coil with an impedance of 2 Ω.
• Very low installation depth for installation in confined spaces.
• Optimized for extremely compact enclosures from 14 l.
• The Air Intercooling Revolution (AIR) avoids the limitations associated with air compression.
• Unrivaled mechanical deflection 20% higher than traditional designs.
• Six-layer copper voice coil (38 mm) ensures high heat capacity.
• The design of the rear part without ventilation allows to reduce the depth of the subwoofer.
• A robust protective grid is included in the package.
• Die-cast aluminum frame.
• Fixed horizontal spring clamps 8 mm².

Catalog number	MPS 250 S2
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.	500 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.	1000W
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.	82.5 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 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.	82.6 mm
Recommended enclosure volumeThe closed enclosure is characterized by a simple construction. Closed enclosures are usually smaller than bass-reflex enclosures, and a special damping fleece is used for their damping. A closed baffle has the advantage of preventing an acoustic short between the front and back radiation of the subwoofer diaphragm. The disadvantage is that the closed enclosure raises the natural resonance frequency of the used subwoofer and thereby also increases the lower limit frequency. This is because the back side of the diaphragm is forced to compress and dilute the air inside the enclosure when the subwoofer is radiating in a closed enclosure. This adds to the inherent stiffness of the subwoofer's oscillation system the stiffness of the air in the closed enclosure. This causes an increase in the stiffness of the oscillating system and thus an increase in the resonant frequency of the entire system: subwoofer -> loudspeaker. The increase in resonant frequency for a given subwoofer is greater, the smaller the volume of air in the closed enclosure. The relatively small volume of air in the closed enclosure acts on the subwoofer as an acoustic spring when radiating the back side of the membrane into the enclosed enclosure. USE: Mainly for quality bass listening in the entire band with an emphasis on detail and accurate reproduction in the lower band. Pros and cons: + pure reproduction + small closets + easier tuning - low level of efficiency in deep bass - loudness only at the cost of enormous deflection of the membrane - a significant acoustic pressure cannot be expected	14.2 l
Recommended bass reflex speaker volumeA bass reflex enclosure is designed in the same way as a closed enclosure, but it also has a so-called bass reflex mouthpiece, or "bass reflex" or slot. Needle foam is used to dampen bass reflex enclosures. USE: The ideal use is in cases where the listener wants to achieve a high volume and a good sound pressure level. It is the best compromise between sound quality and performance and is also the most commonly used Pros and cons: + good efficiency in deep bass + a small deflection of the membrane is enough for a large volume - reproduction less accurate than with closed enclosures	17 years old
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.	28 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.	24.5 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.	16.8
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.	0.45
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.	5.3
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.	0.41
Subwoofer voice coil diameterThe larger the diameter of the voice coil, the more load capacity the subwoofer has, in layman's terms.	38 mm
MassSubwoofer weight in kilograms. The weight is usually given net, i.e. without packaging.	5.11 kg