RE Audio SX18 D4

18″ subwoofer · dual 4 Ω

Fs 45.1 HzQts 1.40Vas 1.77 ft³

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 volume3.53 ft³ (100 L)
Qtc1.71
Fc55 Hz
F3 (−3 dB, no cabin gain)39 Hz
Example box (outside)31 1/2″ × 20 1/2″ × 12 15/16″
Open sealed box in designer

Ported

Net volume6.99 ft³ (198 L)
Tuning (Fb)38 Hz
Portslot 2 3/8 × 19 1/16″, 6 3/8″ long
Port velocity at 300 W61 ft/s
F3 (−3 dB, no cabin gain)29 Hz
Example box (outside)31 1/2″ × 20 1/2″ × 23 15/16″
Open ported box in designer
2030405060801001502007278849096102HzdB
Sealed Ported · SPL in dB at 1 W / 1 m, no cabin gain

Thiele/Small parameters

Fs45.1 Hz
Qts1.40
Qes1.601
Qms10.91
Vas1.77 ft³
Re (one coil)3.97 Ω
Sd180.5 in²
Xmax≈ 0.39″
Mms478 g calc.
BL18.3 T·m calc.
EBP28 — suits sealed calc.
Sensitivity, 1 W / 1 m86.6 dB calc.

General

Size18″
Voice coilsdual 4 Ω
RMS power—

Mounting dimensions

Ø≈ 17 11/16″cutout ≈ Ø16 9/16″mounting depth ≈ 8 1/4″magnet Ø≈ 10 3/4″
Cutout diameter≈ 16 9/16″
Mounting depth≈ 8 1/4″

Judging by its value, the published Re is for both coils in parallel — converted to per coil.

“≈” 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 RE Audio 18″ models