Fi Audio Xv3 15 D2

15″ subwoofer · dual 2 Ω · 1,000 W RMS

34.7 HzFs, resonance

0.61Qts

2.12 ft³Vas

1.06″Xmax

1,000 WRMS

Source	web.archive.org · manufacturer data
Checked against source	October 2026
Thiele/Small parameters	complete
Mounting dimensions	3 of 4 — missing: magnet diameter; the designer will use an estimate

The published specs don’t add up:

The spec sheet's Qts 0.51 doesn't match its Qes and Qms (they give 0.61).

Recommended box

For a sedan, one sub, 1,000 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

2.86 ft³ (81 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)	31 1/2″ × 18 1/8″ × 11 7/8″

Open sealed box in designer

Ported

deeper, louder

2.01 ft³ (57 L)

Net volume

Tuning (Fb)	34 Hz
Port	slot 1 15/16 × 16 11/16″, 33″ long
Port velocity at 1,000 W	61 ft/s
F3 (−3 dB, no cabin gain)	34 Hz
Example box (outside)	22 13/16″ × 18 1/8″ × 15 15/16″

Open ported box in designer

Deeper: 4.87 ft³ (138 L) tuned to 30 Hz, 31 1/2″ × 18 1/8″ × 22 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	15″
Voice coils	dual 2 Ω
RMS power	1,000 W
Fs	34.7 Hz
Qts	0.61
Qes	0.66
Qms	8.01
Vas	2.12 ft³

Re (one coil)	1.4 Ω
Sd	125.6 in²
Xmax	1.06″
Vd	133.5 in³ calc.
Mms	325 g calc.
BL	12.3 T·m calc.
EBP	53 — sealed or ported calc.
Sensitivity, 1 W / 1 m	87.8 dB calc.

Mounting dimensions

Cutout diameter	14 1/8″
Mounting depth	8 3/4″
Overall diameter	15 5/8″

“≈” 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

Other Fi Audio 15″ models

Fi Audio Alpha v1 15 S1 15″ · 1 Ω
Fi Audio Alpha v1 15 S2 15″ · 2 Ω
Fi Audio Alpha v1 15 S4 15″ · 4 Ω
Fi Audio Alpha v2 15 S2 15″ · 2 Ω
Fi Audio Alpha v2 15 S4 15″ · 4 Ω
Fi Audio BL-NEO 15 D1 15″ · dual 1 Ω
Fi Audio BL-NEO 15 D2 15″ · dual 2 Ω
Fi Audio BL15 D1 15″ · dual 1 Ω
Fi Audio BL15 D2 15″ · dual 2 Ω
Fi Audio BL15v3 D1 15″ · dual 1 Ω
Fi Audio BL15v3 D2 15″ · dual 2 Ω
Fi Audio BL15v3.1 D1 15″ · dual 1 Ω

Similar 15″ subwoofers from other brands

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

DD Audio 815f D1 2.83 ft³ sealed · 1.98 ft³ ported
DD Audio 815f D2 2.83 ft³ sealed · 1.98 ft³ ported
Kicx ZC15 (2+2) 2.83 ft³ sealed · 1.98 ft³ ported
Ground Zero GZRW 15XSPL (2x2 Ohm) 2.65 ft³ sealed · 1.98 ft³ ported
Avatar SST-315 D2 2.83 ft³ sealed · 1.98 ft³ ported
Swat SBT-15 v.3 2.83 ft³ sealed · 1.98 ft³ ported

FAQ

What box does the Fi Audio Xv3 15 D2 need?

Recommended net volume: 2.86 ft³ sealed, 2.01 ft³ ported tuned to 34 Hz — for one sub in a sedan at 1,000 W. Fit the box to your space and amp in the free calculator, with plans and a cut sheet.

What are the Fi Audio Xv3 15 D2 Thiele/Small specs?

Fs 34.7 Hz, Qts 0.61, Vas 2.12 ft³, Xmax 1.06″, Sd 125.6 in².

What is the Fi Audio Xv3 15 D2 mounting depth?

Mounting depth is 8 3/4″, cutout diameter 14 1/8″. The inside depth of the box must exceed the mounting depth by at least 1″.

How much power does the Fi Audio Xv3 15 D2 handle and how do I wire it?

RMS power rating: 1,000 W. Dual 2 Ω voice coils: series gives 4 Ω, parallel gives 1 Ω at the amp. Wiring for several subs and amp power — in the wiring calculator.