Sundown Audio Uv2-18 D4

18″ subwoofer · dual 4 Ω · 2,000 W RMS

Fs 30.9 HzQts 0.58Vas 4.05 ft³Xmax 1.18″

Recommended box

For a sedan, one sub, 2,000 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 volume4.52 ft³ (128 L)
Qtc0.80
Fc43 Hz
F3 (−3 dB, no cabin gain)40 Hz
Example box (outside)31 1/2″ × 20 7/8″ × 15 5/8″
Open sealed box in designer

Ported

Net volume7.80 ft³ (221 L)
Tuning (Fb)29 Hz
Portslot 4 15/16 × 19 7/16″, 30 7/8″ long
Port velocity at 2,000 W65 ft/s
F3 (−3 dB, no cabin gain)25 Hz
Example box (outside)31 1/2″ × 20 7/8″ × 30 13/16″
Open ported box in designer
203040506080100150200667278849096HzdB
Sealed Ported · SPL in dB at 1 W / 1 m, no cabin gain

Thiele/Small parameters

Fs30.9 Hz
Qts0.58
Qes0.65
Qms5.51
Vas4.05 ft³
Re (one coil)3.04 Ω
Sd201.2 in²
Xmax1.18″
Vd237.6 in³ calc.
Mms552 g calc.
BL22.4 T·m calc.
EBP48 — suits sealed calc.
Sensitivity, 1 W / 1 m89.2 dB calc.

General

Size18″
Voice coilsdual 4 Ω
RMS power2,000 W

Mounting dimensions

Ø18 5/8″cutout Ø16 7/8″mounting depth 10″magnet Ø9 11/16″
Cutout diameter16 7/8″
Mounting depth10″
Overall diameter18 5/8″
Magnet diameter9 11/16″

The spec sheet's Sd of 254.5 in² is the area of a 18″ circle, not the cone's radiating area — not used.

Cone area (Sd) calculated from Fs, Vas and Mms: 201.2 in².

“≈” 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 18″ models