Helix K 12W-SVC2 (1x2 Ohm)

12″ subwoofer · 2 Ω · 300 W RMS

Fs 31 HzQts 0.48Vas 1.87 ft³Xmax 0.31″
The published specs don’t add up:

Recommended box

For a sedan, one sub, 300 W. It’s the same math as the designer’s step-by-step mode, where you can fit the box to your space, vehicle and amp and get plans, a cut sheet and DXF.

Sealed

Net volume1.02 ft³ (29 L)
Qtc0.80
Fc52 Hz
F3 (−3 dB, no cabin gain)49 Hz
Example box (outside)14 9/16″ × 14 9/16″ × 12 11/16″
Open sealed box in designer

Ported

Net volume3.11 ft³ (88 L)
Tuning (Fb)29 Hz
Portslot 1 3/4 × 14 5/16″, 21 13/16″ long
Port velocity at 300 W60 ft/s
F3 (−3 dB, no cabin gain)26 Hz
Example box (outside)31 1/2″ × 15 3/4″ × 16″
Open ported box in designer
203040506080100150200606672788490HzdB
Sealed Ported · SPL in dB at 1 W / 1 m, no cabin gain

Thiele/Small parameters

Fs31 Hz
Qts0.48
Qes0.54
Qms4.03
Vas1.87 ft³
Re2 Ω
Sd79.8 in²
Xmax0.31″
Vd25.1 in³ calc.
Mms187 g calc.
BL11.6 T·m calc.
EBP57 — sealed or ported calc.
Sensitivity, 1 W / 1 m86.7 dB calc.

General

Size12″
Voice coils2 Ω
RMS power300 W

Mounting dimensions

Ø12 7/16″cutout Ø11 1/4″mounting depth 5 11/16″magnet Ø≈ 7 5/16″
Cutout diameter11 1/4″
Mounting depth5 11/16″
Overall diameter12 7/16″

“≈” means the value isn’t in the spec sheet and a typical value for the size is used; “calc.” means it’s calculated from the published parameters. Check the manufacturer’s spec sheet before you build.

Data sources

Other Helix 12″ models