The anatomy of an amazing car subwoofer

An closer look at Alpine's Type-R

By

Buck Pomerantz

Buck Pomerantz was born and raised in Philadelphia. His parents bought their first television set when he was born. He figured out how to run it by the time he was two. Besides athletics, his formative interests included electronics, amateur radio, music, and stage crew work. He got his BA in writing from Brown University. Then he joined a rock 'n roll band as their soundman and moved to Charlottesville, Virginia. After that venture failed, he spent time in Boston, New Orleans, and Berkeley. He worked in a music store in Austin manufacturing, installing, repairing, and operating sound systems for recording studios, clubs, and bands. He moved back to Charlottesville, ran a little recording studio and finally joined Crutchfield as a copywriter. He has 2 grown children and 3 grandchildren, but after a good nap he can still rock out.

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What makes a great subwoofer sound so good? For Alpine, it's the blend of high-quality materials and acute attention to detail in design. Each part works in harmony to play your music loudly and clearly.

Take Alpine's Type-R subwoofers, for example. They utilize six patented (two pending) innovations in the technology of creating bass to bring you some of the loudest, cleanest-sounding, and longest-living subs in their class. It's not just the up-to-date materials of the individual pieces — it's also the way they're put together, and even their very shapes, that contribute to the production of superior sound.

We've highlighted some of the Type-R's finest features in the cutaway drawing below. Click on the numbers to read more.

Warm
Air
Cool Air
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More cone movement means louder, deeper bass

The High-Amplitude Multi-Roll surround (HAMR, patent pending) allows the cone to move much farther forward and back than a usual round-type surround. This pushes more air, for louder, deeper bass. Its unique shape also lets Alpine put a larger subwoofer cone in the standard-sized frame.

HAMR surround
HAMR chart

A HAMR surround unfolds as it straightens, so the cone can move to a very high position. This is called its maximum safe excursion point, or its "x-max."

Ordinary surround
Ordinary chart

A normal curved surround resists straightening then pops suddenly to a stop, putting stress at its attachment points. The HAMR shape reduces that stress by moving more smoothly as it folds and unfolds.

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Straight movement equals clean sound

Working with the HAMR suspension system, the patented Progressive Conex Spider assembly eliminates the drag that connection wires often cause, and helps maintain straight cone and voice coil movements, which reduces distortion.

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Plays cool, lasts longer

A subwoofer's voice coil puts out a lot of heat when it plays, which can damage the sub if not taken care of. Alpine's patented "Airflow Management and Heat Transfer System" uses the motion of the sub itself to suck cool air in to flow over the hottest pieces, and force hot air past heatsinks and outside to cool. The Type-R's patent-pending Single-Piece Frame & Shorting Sleeve (part of the voice coil gap) reduces distortion and also contributes to the cooling system, taking heat away from the voice coil, and extending the life of the sub.

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Massive magnets control accurate reproduction

The power to create clear and distortion-free music depends on the strength and shape of the magnetic field in the sub's motor assembly. Alpine packs each Type-R sub with a 10-piece segmented magnet made of high-grade strontium ferrite that emits a large magnetic field, while maintaining a compact profile. The shape of the pole piece, including a patented Compound Radius Curvature, focuses the magnetic field in the voice coil gap, reducing distortion. It also doubles as an air vent used in the cooling system.

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