Sundown Audio Uv1-12 D4

12″ subwoofer · dual 4 Ω · 1,500 W RMS

Fs 40 HzQts 0.34Vas 0.43 ft³Xmax 1.18″
The published specs don’t add up:

Recommended box

For a sedan, one sub, 1,500 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 volume0.72 ft³ (20.5 L)
Qtc0.43
Fc51 Hz
F3 (−3 dB, no cabin gain)100 Hz
Example box (outside)14 3/16″ × 14 3/16″ × 10 1/4″
Open sealed box in designer

Ported

Net volume1.45 ft³ (41 L)
Tuning (Fb)27 Hz
Portround port Ø2 1/2″, 10 13/16″ long
Port velocity at 1,500 W488 ft/s
F3 (−3 dB, no cabin gain)85 Hz
Example box (outside)23 1/8″ × 15 3/4″ × 10 1/4″
Open ported box in designer
2030405060801001502006066727884HzdB
Sealed Ported · SPL in dB at 1 W / 1 m, no cabin gain

Thiele/Small parameters

Fs40 Hz
Qts0.34
Qes0.38
Qms2.93
Vas0.43 ft³
Re (one coil)3.05 Ω
Sd≈ 76 in²
Xmax1.18″
EBP105 — suits ported calc.
Sensitivity, 1 W / 1 m85.2 dB calc.

General

Size12″
Voice coilsdual 4 Ω
RMS power1,500 W

Mounting dimensions

Ø12 13/16″cutout Ø11″mounting depth 7 3/4″magnet Ø9 11/16″
Cutout diameter11″
Mounting depth7 3/4″
Overall diameter12 13/16″
Magnet diameter9 11/16″

The spec sheet's Sd of 114 in² is the area of a 12″ circle, not the cone's radiating area — not used.

“≈” 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 Sundown Audio 12″ models