Fi Audio FiDay 12 S2

12″ subwoofer · 2 Ω · 600 W RMS

32.4 HzFs, resonance

0.56Qts

1.54 ft³Vas

0.67″Xmax

600 WRMS

Source	web.archive.org · manufacturer data
Checked against source	October 2026
Thiele/Small parameters	complete
Mounting dimensions	0 of 4 — missing: cutout, mounting depth, frame outer diameter, magnet diameter; the designer will use an estimate

Recommended box

For a sedan, one sub, 600 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

smaller, tighter

1.52 ft³ (43 L)

Net volume

Bass character (Qtc)	Tight and punchy · 0.80
Fc	46 Hz
F3 (−3 dB, no cabin gain)	43 Hz
Example box (outside)	14 3/16″ × 14 3/16″ × 18 11/16″

Open sealed box in designer

Ported

deeper, louder

1.24 ft³ (35 L)

Net volume

Tuning (Fb)	34 Hz
Port	slot 1 9/16 × 14 5/16″, 38 5/16″ long
Port velocity at 600 W	53 ft/s
F3 (−3 dB, no cabin gain)	34 Hz
Example box (outside)	31 1/2″ × 15 3/4″ × 9 9/16″

Open ported box in designer

Deeper: 2.90 ft³ (82 L) tuned to 30 Hz, 31 1/2″ × 15 3/4″ × 16 3/8″ outside — a bigger box with flatter deep bass. Open in the calculator

Where to buy Amazon

Sealed Ported · SPL in dB at 1 W / 1 m, no cabin gain

Thiele/Small parameters

Size	12″
Voice coils	2 Ω
RMS power	600 W
Fs	32.4 Hz
Qts	0.56
Qes	0.61
Qms	7.17
Vas	1.54 ft³

Re	1.8 Ω
Sd	74.4 in²
Xmax	0.67″
Vd	49.8 in³ calc.
Mms	180 g calc.
BL	10.4 T·m calc.
EBP	53 — sealed or ported calc.
Sensitivity, 1 W / 1 m	85.9 dB calc.

Mounting dimensions

Cutout diameter	≈ 11 1/8″
Mounting depth	≈ 5 7/8″

“≈” 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

web.archive.org/web/20151230064157/http://www.ficaraudio.com:80/product/fiday-12

Other Fi Audio 12″ models

Fi Audio Alpha 12 S2 12″ · 2 Ω
Fi Audio Alpha 12 S4 12″ · 4 Ω
Fi Audio Alpha v1 12 S1 12″ · 1 Ω
Fi Audio Alpha v1 12 S2 12″ · 2 Ω
Fi Audio Alpha v1 12 S4 12″ · 4 Ω
Fi Audio Alpha v2 12 S2 12″ · 2 Ω
Fi Audio Alpha v2 12 S4 12″ · 4 Ω
Fi Audio Alpha v2.1 12 S2 12″ · 2 Ω
Fi Audio Alpha v2.1 12 S4 12″ · 4 Ω
Fi Audio BL-NEO 12 D1 12″ · dual 1 Ω
Fi Audio BL-NEO 12 D2 12″ · dual 2 Ω
Fi Audio BL12 D1 12″ · dual 1 Ω

Similar 12″ subwoofers from other brands

Close in Fs, Qts and Vas — a box of similar volume will suit them.

CT Sounds TROPO-12 D2 1.55 ft³ sealed · 1.02 ft³ ported
Cerwin-Vega Mobile VMAX124 (VMAX 12" DVC 4ohm) 1.55 ft³ sealed · 1.59 ft³ ported
Alpine SWS-12D4 (Type-S) 1.55 ft³ sealed · 1.24 ft³ ported
Massive Audio GTS12 1.66 ft³ sealed · 1.24 ft³ ported
Massive Audio UFO12V2 1.66 ft³ sealed · 1.24 ft³ ported
Sony XS-L12S 1.41 ft³ sealed · 1.20 ft³ ported

FAQ

What box does the Fi Audio FiDay 12 S2 need?

Recommended net volume: 1.52 ft³ sealed, 1.24 ft³ ported tuned to 34 Hz — for one sub in a sedan at 600 W. Fit the box to your space and amp in the free calculator, with plans and a cut sheet.

What are the Fi Audio FiDay 12 S2 Thiele/Small specs?

Fs 32.4 Hz, Qts 0.56, Vas 1.54 ft³, Xmax 0.67″, Sd 74.4 in².

How much power does the Fi Audio FiDay 12 S2 handle and how do I wire it?

RMS power rating: 600 W. Wiring for several subs and amp power — in the wiring calculator.