MM2154 Car Subwoofer from Polk Audio

This is the MM2154 15" Subwoofer. Its ultra-stiff Dynamic Balance Cone womps out massive bass. Its Dish Cone design is mechanically supported by a unique Vented Cone Coupler. This support increases the sub's axial rigidity. (It's like "Viagra for your subwoofer”!) Even with huge max power ratings, these subs are optimized for smaller enclosures, so they fit where you want your bass.

MM2154 Technologies and Features:

Ultra-stiff Metalized Polypropylene Dynamic Balance Cone for massive bass.
Dish Cone design is supported by a Vented Cone Coupler, increasing axial rigidity "like Viagra for your subwoofer!"
State-of-the-art laser-based Klippel measurement technology perfectly centers the subwoofer’s voice coil in the magnetic field, improving X-max and BL linearity, and the sub’s micro and macro dynamics, for deep, precise, stomach-shaking and spine-wrenching bass.
Optimized for high performance in small sealed enclosures but versatile enough to pound hard even in bandpass and vented enclosures¾ Flat, deep bass with great extension as only Polk/MOMO can do it.
Built tough and backed by one of the best warranty in the car audio world: Three years parts and labor.
Triple vented for maximum airflow, high dissipation and high power handling: Vented Coil/Cone Coupler, Vented Spider Platform and Vented Pole Piece all allow cooling air to freely flow over the heat-generating components and better harness all the watts your amp can dish out.
Durable, airtight Rubber Surround for a long life of extended linear motion, optimized to achieve the longest throw possible for the cone: "Big cone, big throw!"
Huge, fire-retardant flat NOMEX^® Spider allows extended linear motion while providing highly reliable mechanical and thermal stability.
Acoustically inert Stamped Steel Basket with massive, rock-solid non-flexing magnet and motor assembly with removable Rubber Magnet Boot for more damping and deeper install flexibility (reduces product depth by 1/4-inch).
Anti-Resonance Trim Gasket for tight fit with G Series Grilles, removable for over 1/4² of installation flexibility.
Heat shrink rubber coated tinsel leads with strain relief terminal connections to take the punishment of long excursion bass.
Professional Grade Nickel Plated Locking Push Terminals for secure connections; big holes accept nice fat wire, big as 12 gauge!

Marine Certified Polk/MOMO speakers are built tough to withstand the toughest environments so they are perfect for use in boats of all types. That's why Correct Craft offers Polk/MOMO speakers in their award-winning Nautiques ski and wakeboarding boats. Professional wakeboarder Brian Francis choose Polk/MOMO speakers woofers and amps for his MasterCraft boat and Chevy Avalanche truck for maximum entertainment and excitement on the road and wave.
Optional MOMO Design "Quasar II" rim-style Grille available separately at your authorized Polk Audio AutoSound dealer or direct from Polk.

When you consider your car an extension of your personality, Polk Audio/MOMO High Performance Car Audio is the perfect synthesis of technology and design.

What are Thiele/Small parameters?

Thiele/Small parameters are electro-mechanical measurements that are used to mathematically predict the low-end response of a woofer. They were first developed by Neville Thiele and Richard Small. Thiele/Smalls measure such things as the woofer’s moving mass, magnet strength, resonant frequency and damping. These characteristics are used to predict the behavior of a given speaker in different loudspeaker cabinet designs. Computers have pretty much taken over the measurements, but we like to keep a hands-on knowledge of T/S parameters, so here are some of the Thiele/Small parameters explained:

Fs - is the free air resonant frequency of a speaker.
Qes – "Q" is the mathematical ratio of the amplitude vs. the bandwidth of a resonance peak curve. This T/S is the measurement of the electrical "Q" of a speaker, having to do with electrical impedance.
Qms - This is the measurement of the mechanical "Q" of a speaker, and has to do with cone motion.
Cms - is the "compliance" (or "un-stiffness") of the mechanical system of a speaker; a measurement of how stiff (or "un-stiff") the spider and surround are together.
Sd - is simply the surface area of the "transducer diaphragm" (or, "speaker cone" in non-engineer-speak).
Xmax - is a calculation of the maximum displacement for the cone for undistorted operation.
Re - is the DC electrical resistance of the voice coil. (Whew, that was easy!)
Bl – This is a measurement of the magnetic strength ("B") that a voice coil is exposed to, times the length ("l") of coil actually exposed to the magnetic field "in the gap" (the area in which the voice coil moves freely).
Mms – This T/S parameter is simply a measurement of the mass ("M") of the moving mechanical system ("ms") of a speaker, plus the air in front of it.

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