Sundown Audio SAv2-18 D4

18″ subwoofer · dual 4 Ω · 1,250 W RMS

Fs 31.9 HzQts 0.39Vas 3.78 ft³Xmax 0.75″

Recommended box

For a sedan, one sub, 1,250 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 volume1.87 ft³ (53 L)
Qtc0.69
Fc55 Hz
F3 (−3 dB, no cabin gain)60 Hz
Example box (outside)19 11/16″ × 19 11/16″ × 12 9/16″
Open sealed box in designer

Ported

Net volume3.92 ft³ (111 L)
Tuning (Fb)34 Hz
Portslot 2 15/16 × 19 1/16″, 27″ long
Port velocity at 1,250 W63 ft/s
F3 (−3 dB, no cabin gain)32 Hz
Example box (outside)31 1/2″ × 20 1/2″ × 17 3/16″
Open ported box in designer
203040506080100150200667278849096HzdB
Sealed Ported · SPL in dB at 1 W / 1 m, no cabin gain

Thiele/Small parameters

Fs31.9 Hz
Qts0.39
Qes0.458
Qms2.85
Vas3.78 ft³
Re (one coil)3.03 Ω
Sd199.9 in²
Xmax0.75″
Vd149.6 in³ calc.
Mms550 g calc.
BL27 T·m calc.
EBP70 — sealed or ported calc.
Sensitivity, 1 W / 1 m90.8 dB calc.

General

Size18″
Voice coilsdual 4 Ω
RMS power1,250 W

Mounting dimensions

Ø18 11/16″cutout Ø16 11/16″mounting depth 10 1/8″magnet Ø8 11/16″
Cutout diameter16 11/16″
Mounting depth10 1/8″
Overall diameter18 11/16″
Magnet diameter8 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: 199.9 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