Quantum Audio QWX4000/12D4

12″ subwoofer · dual 4 Ω

45.5 HzFs, resonance

0.72Qts

0.37 ft³Vas

0.51″Xmax

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, 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

smaller, tighter

0.74 ft³ (21 L)

Net volume

Bass character (Qtc)	Tight and punchy · 0.89
Fc	56 Hz
F3 (−3 dB, no cabin gain)	48 Hz
Example box (outside)	14 3/16″ × 14 3/16″ × 10 7/16″

Open sealed box in designer

Ported

deeper, louder

1.20 ft³ (34 L)

Net volume

Tuning (Fb)	34 Hz
Port	slot 1 9/16 × 14 5/16″, 39 9/16″ long
Port velocity at 300 W	47 ft/s
F3 (−3 dB, no cabin gain)	29 Hz
Example box (outside)	31 1/2″ × 15 3/4″ × 9 1/2″

Open ported box in designer

Deeper: 2.19 ft³ (62 L) tuned to 29 Hz, 31 1/2″ × 15 3/4″ × 12 11/16″ 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	dual 4 Ω
RMS power	—
Fs	45.5 Hz
Qts	0.72
Qes	0.857
Qms	4.6
Vas	0.37 ft³

Re (one coil)	3.4 Ω
Sd	76.1 in²
Xmax	0.51″
Vd	38.9 in³ calc.
Mms	396 g calc.
BL	21.2 T·m calc.
EBP	53 — sealed or ported calc.
Sensitivity, 1 W / 1 m	82.6 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/20240802105857/https://quantumaudio.net/wp-content/uploads/2

Other Quantum Audio 12″ models

Quantum Audio Q800/12D 12″ · dual 4 Ω
Quantum Audio Q800/12S 12″ · 4 Ω
Quantum Audio Q2000/12D 12″ · dual 4 Ω
Quantum Audio Q2500/12D 12″ · dual 4 Ω
Quantum Audio Q3000/12D 12″ · dual 4 Ω
Quantum Audio QFW12D4 12″ · dual 4 Ω
Quantum Audio QPW3000/12D4 12″ · dual 4 Ω
Quantum Audio QSW12F 12″ · 4 Ω
Quantum Audio QW1000/12D4 12″ · dual 4 Ω
Quantum Audio QW1000/12S4 12″ · 4 Ω
Quantum Audio QW3000/12D4 12″ · dual 4 Ω
Quantum Audio QW5000/12D4 12″ · dual 4 Ω

Similar 12″ subwoofers from other brands

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

DC Audio Level 4 12 D1 0.95 ft³ sealed · 1.13 ft³ ported
DC Audio Level 4 12 D2 0.95 ft³ sealed · 1.13 ft³ ported
DC Audio Level 4 12 D4 0.95 ft³ sealed · 1.13 ft³ ported
Lanzar OPTI1233D 1.06 ft³ sealed · 1.20 ft³ ported
DC Audio RS 12 D1 0.71 ft³ sealed · 1.24 ft³ ported
DC Audio RS 12 D2 0.71 ft³ sealed · 1.24 ft³ ported

FAQ

What box does the Quantum Audio QWX4000/12D4 need?

Recommended net volume: 0.74 ft³ sealed, 1.20 ft³ ported tuned to 34 Hz — for one sub in a sedan at 300 W. Fit the box to your space and amp in the free calculator, with plans and a cut sheet.

What are the Quantum Audio QWX4000/12D4 Thiele/Small specs?

Fs 45.5 Hz, Qts 0.72, Vas 0.37 ft³, Xmax 0.51″, Sd 76.1 in².