Focal Expert P 20 F (Flax, SVC 4 ohm)

8″ subwoofer · 4 Ω · 250 W RMS

Fs 38.5 HzQts 0.55Vas 0.42 ft³Xmax 0.39″

Recommended box

For a sedan, one sub, 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 volume0.39 ft³ (11 L)
Qtc0.79
Fc56 Hz
F3 (−3 dB, no cabin gain)53 Hz
Example box (outside)10 5/8″ × 10 5/8″ × 10 1/16″
Open sealed box in designer

Ported

Net volume1.13 ft³ (32 L)
Tuning (Fb)31 Hz
Port2 round ports Ø2 1/2″, 22 11/16″ long
Port velocity at 250 W91 ft/s
F3 (−3 dB, no cabin gain)27 Hz
Example box (outside)29 15/16″ × 15 3/4″ × 7 1/16″
Open ported box in designer
2030405060801001502006066727884HzdB
Sealed Ported · SPL in dB at 1 W / 1 m, no cabin gain

Thiele/Small parameters

Fs38.5 Hz
Qts0.55
Qes0.61
Qms5.5
Vas0.42 ft³
Re3.4 Ω
Sd33.5 in²
Xmax0.39″
Vd13.2 in³ calc.
Mms94 g calc.
BL11.3 T·m calc.
EBP63 — sealed or ported calc.
Sensitivity, 1 W / 1 m82.5 dB calc.

General

Size8″
Voice coils4 Ω
RMS power250 W

Mounting dimensions

Ø8 7/16″cutout ≈ Ø7 5/8″mounting depth 4 5/8″magnet Ø≈ 4 15/16″
Cutout diameter≈ 7 5/8″
Mounting depth4 5/8″
Overall diameter8 7/16″

“≈” 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 Focal 8″ models