DD Audio 3518i ESP D2

18″ subwoofer · dual 2 Ω · 1,200 W RMS

Fs 28.9 HzQts 0.82Vas 5.16 ft³Xmax 0.69″

Recommended box

For a sedan, one sub, 1,200 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 volume4.13 ft³ (117 L)
Qtc1.23
Fc43 Hz
F3 (−3 dB, no cabin gain)33 Hz
Example box (outside)31 1/2″ × 20 7/8″ × 14 7/16″
Open sealed box in designer

Ported

Net volume6.99 ft³ (198 L)
Tuning (Fb)33 Hz
Portslot 3 3/8 × 19 7/16″, 16 3/16″ long
Port velocity at 1,200 W63 ft/s
F3 (−3 dB, no cabin gain)28 Hz
Example box (outside)31 1/2″ × 20 7/8″ × 25″
Open ported box in designer
2030405060801001502007278849096102HzdB
Sealed Ported · SPL in dB at 1 W / 1 m, no cabin gain

Thiele/Small parameters

Fs28.9 Hz
Qts0.82
Qes0.97
Qms5.4
Vas5.16 ft³
Re (one coil)≈ 1.7 Ω
Sd≈ 180.6 in²
Xmax0.69″
EBP30 — suits sealed calc.
Sensitivity, 1 W / 1 m87.6 dB calc.

General

Size18″
Voice coilsdual 2 Ω
RMS power1,200 W

Mounting dimensions

Ø18 1/4″cutout Ø16 3/4″mounting depth 10 7/8″magnet Ø≈ 10 7/8″
Cutout diameter16 3/4″
Mounting depth10 7/8″
Overall diameter18 1/4″

“≈” 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 DD Audio 18″ models