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Alpine SWX-1243D

Type-X 12" subwoofer with dual 4-ohm voice coils

Item # 500SWX1243

Feed your Alpine Type-X subwoofer some serious power, and it'll unleash powerful bass to enhance your journey.

Feed your Alpine Type-X subwoofer some serious power, and it'll unleash powerful bass to enhance your journey.

Discontinued item

Item # 500SWX1243

About the Alpine SWX-1243D

Feed your Alpine Type-X subwoofer some serious power, and it'll unleash powerful bass to enhance your journey. And Alpine's advanced design, quality materials, and rigorous construction ensure that you'll get years of reliable use.
Alpine Authorized Online Dealer

Feed your Alpine Type-X subwoofer some serious power, and it'll unleash powerful bass to enhance your journey. And Alpine's advanced design, quality materials, and rigorous construction ensure that you'll get years of reliable use.

The SWX-1243D 12" subwoofer features a 3-layer cone — a layer of Kevlar®, a layer of plastic film, and a bottom layer of pulp reinforced with Kevlar. This design provides outstanding response and accuracy, while the cone's parabolic shape maintains rigidity and strength. The multi-roll Santoprene™ rubber surround maximizes the cone's performance with its ability to go deep. The concealed mounting gasket gives your sub installation a clean look.

On the inside, the SWX-1243D is all business. A massive, triple-stacked strontium magnet anchors the sub, while the single-piece cast aluminum frame and motor support holds provides the backbone you'll need for big bass. Increased venting and heat dissipation areas keep your sub running cool, so it'll survive conditions that would destroy lesser speakers. This bruiser can handle up to 1,000 watts RMS, so don't hesitate to give it some juice.

You can wire the dual 4-ohm voice coils to get the optimum performance from your amp, or to configure a custom setup with multiple subwoofers. Rock the bass the way you want to with the mighty Type-X subwoofer.

Note: If you are wiring this DVC sub for lower impedance, make sure that your amp is compatible. Most 2-channel car amplifiers are stable down to 2 ohms in standard mode, or 4 ohms in bridged operation.

Priced per speaker

Product highlights:

  • 12" subwoofer with dual 4-ohm voice coils
  • pulp/fiber cone reinforced with Kevlar and a layer of Rohacell® plastic film
  • Santoprene rubber surround
  • cast aluminum frame
  • power range: 500-1,000 watts RMS (500 watts per coil)
  • peak power handling: 3,000 watts
  • frequency response: 24-200 Hz
  • sensitivity: 84 dB
  • top-mount depth: 8-11/16"
  • sealed box volume: 0.65-1.25 cubic feet
  • ported box volume: 1.0-2.0 cubic feet
  • warranty: 1 year
  • Our 60-day money-back guarantee
  • MFR # SWX-1243D

What's in the box:

  • One 12" Dual-voice-coil subwoofer
  • 1 Rubber mounting ring (installed)
  • 1 Top-mount rubber concealing ring
  • 1 Bottom-mount rubber mounting ring
  • 2 Voice coil configuration jumpers
  • 2.5mm Hex wrench
  • Application Guide
  • Warranty sheet
  • Customer Care Registration card
  • Important Notice sheet

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More details on the Alpine SWX-1243D

Pat M.

Product Research



Aerospace Cone Material: The Alpine Type-X woofer uses new advanced aerospace materials for the cone, known as Kevlar-Rohacell which provides outstanding strength at a lighter weight. These lighter materials minimize moving mass for greater output efficiency.

Santoprene Surround: The woofer features a High Amplitude Multi Roll Surround  made of injection molded Santoprene, that allows for an incredible amount of linear excursion and greater SPL.

HAMR Engineering: The Alpine Type-X sub is built with HAMR engineering, Alpine's exclusive subwoofer solution for cooler operation, longer life and tight accurate bass.

Dual 4-ohm Voice Coils: The Alpine Type-X woofer features dual 6-layer voice coils which utilize 220°C high-temperature wire with Inner/Outer Winding on a Twin-Wall aluminum former. Dual voice coil woofers offer flexibility in wiring. When the voice coils are wired in parallel with each other, the woofer presents a 2 ohm mono load. When the voice coils are wired in series with each other, the woofer presents an 8 ohm mono load. In addition, each coil may be connected to a different amplifier channel and each channel will see a 4 ohm load.

Terminal Block: The speaker terminals are all located on one side in a machined gold-plated terminal block with 2.5mm Allen-head set screws (an Allen wrench is included). There are slots provided for the supplied voice coil jumpers.

Jumpers: The woofer is equipped with two gold-plated voice coil connection jumpers. These jumpers allow you to wire the voice coils in parallel (for a 2-ohm load) or series (for an 8-ohm load).

Mirrored Progressive Nomex Spiders: This subwoofer has twin mirrored progressive Nomex spiders for added stability and mechanical durability. The custom progressive rolls gives the woofer a longer, more linear stroke (over 23mm one way) with maximum centering and restoring force. Special edge control design and Nomex construction provide excellent tear resistance, strength and long-term reliability. The woofer has reinforced layer tinsel speaker leads that are woven into the spiders for the one-sided terminal layout.

Multi-Stage Ventilation System: The Alpine Type-X woofer has a multi-stage ventilation system with the following features:

  • Cone/Voice Coil Junction Venting: The unique parabolic cone and voice coil attachment piece help to pull cool air into the motor structure.
  • Spider Plateau/Leg Vent System: Two vertical slits are cut into each of the four "legs" of the basket below the spider to allow cool air to flow in and heated air to flow out.
  • Dual Flare Pole: Optimizes airflow into the motor structure across the billet copper shorting sleeves and thermal coupling heat dissipation plate to increase cooling.

Magnet: The woofer is equipped with triple-stacked strontium magnets with an overall magnet weight of 130 ounces.

Cast Aluminum Exo-Frame: The Type-X woofer utilizes a custom, one-piece, cast aluminum Exo-Frame with perimeter venting. The unique design provides the ultimate in voice coil cooling, creating a one-way airflow, keeping hot air from coming into contact with the voice coil. The frame also features an integrated spider landing and heat transfer plate.

Rubber Concealing Ring: The woofer includes a rubber concealing ring to cover the screw holes when top mounting the woofer. The top-mounted concealing ring increases the woofer's top mounting measurement to 1.3125".


Recommended Sealed Box Volume: The sealed box sizes recommended by Alpine range from 0.65 cu/ft to 1.25 cu/ft. with an ideal volume of 1.0 cu/ft.

Recommended Vented Box Volume: The vented box sizes recommended by Alpine range from 1.0 cu/ft to 2.0 cu/ft. with an ideal volume of 1.8 cu/ft. A slot vent, with the dimensions of 12" x 1" x 24", is recommended.

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