Fi Audio Delta 18 D1

18″ subwoofer · dual 1 Ω

Fs 36.3 HzQts 0.40Vas 2.76 ft³Xmax 1.34″

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 volume2.49 ft³ (70.5 L)
Qtc0.58
Fc53 Hz
F3 (−3 dB, no cabin gain)69 Hz
Example box (outside)20 1/16″ × 20 1/16″ × 15 3/16″
Open sealed box in designer

Ported

Net volume3.60 ft³ (102 L)
Tuning (Fb)35 Hz
Portround port Ø5″, 8 1/4″ long
Port velocity at 300 W93 ft/s
F3 (−3 dB, no cabin gain)33 Hz
Example box (outside)27 1/8″ × 20 7/8″ × 15 3/16″
Open ported box in designer
203040506080100150200667278849096HzdB
Sealed Ported · SPL in dB at 1 W / 1 m, no cabin gain

Thiele/Small parameters

Fs36.3 Hz
Qts0.40
Qes0.42
Qms7.61
Vas2.76 ft³
Re (one coil)0.7 Ω
Sd187.6 in²
Xmax1.34″
Vd251.1 in³ calc.
Mms510 g calc.
BL13.9 T·m calc.
EBP86 — sealed or ported calc.
Sensitivity, 1 W / 1 m91.5 dB calc.

General

Size18″
Voice coilsdual 1 Ω
RMS power—

Mounting dimensions

Ø18 1/2″cutout Ø16 3/4″mounting depth 12 3/4″magnet Ø≈ 10 7/8″
Cutout diameter16 3/4″
Mounting depth12 3/4″
Overall diameter18 1/2″

“≈” 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 Fi Audio 18″ models