Kevlar Reinforced Pulp Cone:
This Alpine Type-R subwoofer has a Kevlar reinforced pulp cone. Kevlar adds
strength and tear resistance to the woofer cone while maintaining the benefits
of a pulp cone design. There is also an oversized inverted dust cap of the same
material, which increases rigidity and virtually eliminates distortion at
extreme volume levels.
HAMRS: The woofer features a
High Amplitude Multi Roll Surround (HAMRS), made of injection molded Santoprene,
that allows for an incredible amount of linear excursion and greater SPL.
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 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 integrated tinsel
speaker leads that are woven into the spiders for the one-sided terminal layout.
Cast Aluminum Frame: The woofer
is mounted to a custom cast aluminum frame for added strength. This high mass
frame also dissipates heat quickly to make it an integral part of the woofer's
thermal management system.
Heat Transfer Plate: This
subwoofer contains an integrated heat transfer plate that is thermally coupled
to the voice coil. This plate pulls heat away from the voice coil and transfers
it to the cast aluminum frame, achieving up to 20% additional power handling,
and better reliability.
Magnetically Optimized Motor
Structure: Through Alpine's advanced magnetic circuit design, this woofer
offers better sound quality, and a higher sensitivity and power handling
- Compound Radius Curve Pole
Geometry: This patent-pending design intensifies the magnetic field for
higher SPL and lower distortion. The magnetic field is balanced over a wider
area for better control at high excursion.
- Extra Length Extended Pole:
The extra long pole piece provides additional surface to capture radiated
heat for additional power handling.
- Extra Thick Top Plate: The
extra thick top plate keeps more windings in the magnetic gap for better
- Dual Stacked Magnets: The
dual stacked magnets provide the powerful magnetic energy and extra depth
for high SPL and maximum control.
- Bumped Back Plate: This
"bottomless" design provides extra room for longer cone excursions.
- Optimally Saturated Pole:
The optimally saturated pole reduces magnetically induced heat by
eliminating eddy currents throughout the voice coil stroke, and evens flux
distribution to eliminate "hot spots."
Multi-Stage Ventilation System:
The SWR-1222D 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 five "legs" of the
basket below the spider to allow cool air to flow in and heated air to flow
- Dual Flare Pole Vent:
Another part of the thermal management system is the unique dual flare
design of the pole vent. This maximizes the flow of cooler air to the voice
coil, and results in better power handling.
Dual Voice Coils: For increased
system flexibility, the woofer has two 2-ohm voice coils. When the voice coils
are wired in parallel with each other, the woofer presents a 1-ohm mono load.
When the voice coils are wired in series with each other, the woofer presents an
4-ohm mono load. In addition, each coil may be connected to a different
amplifier channel and each channel will see a 2-ohm load.
Power Handling: This woofer has
a total RMS power rating of 500 watts and a total peak power rating of 1500
watts. Each voice coil carries an RMS power rating of 250 watts and a peak power
rating of 750 watts.
Push Terminals: The push
terminals are all located on one side of the woofer. The terminals will accept
bare wire, pin connectors, banana connectors, and dual banana connectors.
Jumpers: The woofer is equipped
with two 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).
Recommended Sealed Box Volume:
The sealed box sizes recommended by Alpine range from 0.57 cu/ft to 1.0 cu/ft.
Within this range, the ideal size recommended by Alpine is 0.85 cu/ft, so this
is the enclosure recommended by Crutchfield.
Recommended Vented Box Volume:
The vented box sizes recommended by Alpine range from 0.75 cu/ft to 2.0 cu/ft.
Within this range, the ideal size recommended by Alpine is 1.7 cu/ft, so this is
the enclosure recommended by Crutchfield. A slot port with the following
dimensions should be used with the 1.7 cu/ft enclosure: W = 12", H = 1.25", L = 21".
If you cannot use a slot port in your enclosure, you will need a port tube with
the following dimensions: Diameter = 3", L = 9.9".
Recommended Enclosure Volumes:
The manual incorrectly lists the recommended enclosure volumes for this
subwoofer. The recommended enclosure volumes in the Crutchfield database were
obtained directly from Alpine.