Dual 4Ω Voice Coils: The Rockford Fosgate
features dual 4Ω voice coils and a jumper to easily wire them in series or
parallel, presenting either a 2Ω or 8Ω load; the voice coils cannot be
easily wired separately.
SWIFT Terminal: Rockford's proprietary SWIFT Terminal
(Selectable Woofer Impedance Fused Termination) offers a simple and convenient
method of setting the impedance presented by the dual voice coil subwoofer.
The impedance jumper also provides fused protection from severe overload
conditions. With the jumper in the 2Ω position the voice coils are wired
in parallel; with the jumper in the 8Ω position the voice coils are wired
Note: A second jumper is included with the subwoofer,
described in the manual as non-fused. Visually, however, this jumper also
appears to be fused, but at a higher threshold than the factory installed
jumper (possibly high enough to make it effectively non-fused).
Woofer: The Kevlar fiber reinforced paper cone has a hard
anodized aluminum dust cap of equivalent size; the result is a lightweight and
extremely strong cone, reducing piston flex and cone distortion.
VAST Surround: The Vertical Attach Surround Technique (VAST)
increases a speaker's effective radiating cone area without increasing the size
of the basket.
Voice Coil Former: Aluminum voice coil formers offer superior
heat dissipation over other commonly used materials. The hard-anodized finish
increases the former strength. These two factors combine to improve the overall
power handling characteristics of the subwoofer.
Cast Aluminum Basket: The basket is a die-cast aluminum design
to add rigidity and eliminate multiple acoustic resonances. Additionally, the large
aluminum mass helps reduce voice coil former temperature and increase power handling.
Terminals: The proprietary spring terminals will accept bare
wire up to 8-gauge.
Grille: A metal grille is included to protect the subwoofer
and add a finished look. If the sub is bottom mounted and the back is visible,
the grille can be disassembled and just the trim ring can be installed to cover
the mounting screws.
CEA-2031 Compliant: Power handling on the T1D412 subwoofer
conforms to CEA-2031 industry standards. This means the subwoofer has the capacity
to handle its rated power under continuous demand, not just for an instant.
Klippel Verified: The Klippel distortion analyzer, a device
that uses a laser and sophisticated software to do large-scale analysis of drivers
in motion, lets Rockford Fosgate optimize the subwoofer's motor structure, voice
coil alignment, and suspension to yield the best possible performance.
Inductive Damping Heat Sink: The Inductive Damping Heat Sink
(IDSH) secures directly to the top of the magnet structure to improve system
efficiency by reducing both distortion and back EMF (Electo-Magnetic force). It
also radiates heat to reduce the voice coil temperature.
FlexFit Basket: The Flex Fit frame utilizes slots (where
possible) instead of single screw sized holes; allowing slight adjustment of
the speaker when mounted.
Sealed Box: When using a sealed enclosure, Rockford recommends
an internal volume of 1.25 cubic feet. Sealed enclosures provide the most control
over a woofer, will handle a lot of power, and provide accurate sonic reproduction,
making them suitable to all types of music.
Ported Box: Two ported enclosures are recommend:
- Optimum: internal volume of 1.75 cubic
feet using one 4" diameter x 9" long port; this
yields a tuning frequency of 40 Hz and a -3 dB point of 32 Hz
- High Output: internal volume of 2.25
cubic feet using a 3" x 13-3/4" x 25-3/4" slot port;
this yields a tuning frequency of 40 Hz