Sundown Audio Xv4-18 D1

18″ subwoofer · dual 1 Ω · 2,750 W RMS

Fs 25.9 HzQts 0.55Vas 3.31 ft³Xmax 1.18″

Recommended box

For a sedan, one sub, 2,750 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 volume2.90 ft³ (82 L)
Qtc0.80
Fc38 Hz
F3 (−3 dB, no cabin gain)36 Hz
Example box (outside)19 11/16″ × 19 11/16″ × 17 7/8″
Open sealed box in designer

Ported

Net volume6.82 ft³ (193 L)
Tuning (Fb)25 Hz
Portslot 5 1/8 × 19 1/16″, 53 1/16″ long
Port velocity at 2,750 W65 ft/s
F3 (−3 dB, no cabin gain)22 Hz
Example box (outside)31 1/2″ × 20 1/2″ × 32 3/4″
Open ported box in designer
203040506080100150200606672788490HzdB
Sealed Ported · SPL in dB at 1 W / 1 m, no cabin gain

Thiele/Small parameters

Fs25.9 Hz
Qts0.55
Qes0.63
Qms4.13
Vas3.31 ft³
Re (one coil)1.02 Ω
Sd176 in²
Xmax1.18″
Vd207.9 in³ calc.
Mms738 g calc.
BL13.9 T·m calc.
EBP41 — suits sealed calc.
Sensitivity, 1 W / 1 m86.1 dB calc.

General

Size18″
Voice coilsdual 1 Ω
RMS power2,750 W

Mounting dimensions

Ø18 7/16″cutout Ø16 11/16″mounting depth 15″magnet Ø9 1/4″
Cutout diameter16 11/16″
Mounting depth15″
Overall diameter18 7/16″
Magnet diameter9 1/4″

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: 176 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