Sundown Audio Zv7-18 D2

18″ subwoofer · dual 2 Ω · 3,500 W RMS

Fs 27.3 HzQts 0.42Vas 3.35 ft³Xmax 1.65″

Recommended box

For a sedan, one sub, 3,500 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 volume2.93 ft³ (83 L)
Qtc0.62
Fc40 Hz
F3 (−3 dB, no cabin gain)48 Hz
Example box (outside)19 11/16″ × 19 11/16″ × 18 1/16″
Open sealed box in designer

Ported

Net volume4.20 ft³ (119 L)
Tuning (Fb)28 Hz
Portslot 4 3/4 × 19 1/16″, 65 3/16″ long
Port velocity at 3,500 W67 ft/s
F3 (−3 dB, no cabin gain)26 Hz
Example box (outside)31 1/2″ × 20 1/2″ × 26 5/16″
Open ported box in designer
203040506080100150200606672788490HzdB
Sealed Ported · SPL in dB at 1 W / 1 m, no cabin gain

Thiele/Small parameters

Fs27.3 Hz
Qts0.42
Qes0.451
Qms6.37
Vas3.35 ft³
Re (one coil)1.99 Ω
Sd189 in²
Xmax1.65″
Vd312.5 in³ calc.
Mms756 g calc.
BL23.9 T·m calc.
EBP60 — sealed or ported calc.
Sensitivity, 1 W / 1 m88.3 dB calc.

General

Size18″
Voice coilsdual 2 Ω
RMS power3,500 W

Mounting dimensions

Ø18 1/2″cutout Ø16 11/16″mounting depth 15 9/16″magnet Ø10 13/16″
Cutout diameter16 11/16″
Mounting depth15 9/16″
Overall diameter18 1/2″
Magnet diameter10 13/16″

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: 189 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