SPL Dynamics XTR-380D4S

15″ subwoofer · dual 4 Ω · 1,000 W RMS

33.6 HzFs, resonance

0.47Qts

1.88 ft³Vas

0.51″Xmax

1,000 WRMS

Source	web.archive.org · manufacturer data
Checked against source	October 2026
Thiele/Small parameters	not in the spec sheet: Re — typical value for the size used
Mounting dimensions	3 of 4 — missing: magnet diameter; the designer will use an estimate

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

1.17 ft³ (33 L)

Net volume

Bass character (Qtc)	Flat and accurate · 0.76
Fc	54 Hz
F3 (−3 dB, no cabin gain)	54 Hz
Example box (outside)	16 15/16″ × 16 15/16″ × 11 1/16″

Open sealed box in designer

Ported

deeper, louder

2.05 ft³ (58 L)

Net volume

Tuning (Fb)	34 Hz
Port	slot 2 3/16 × 16 5/16″, 34 15/16″ long
Port velocity at 1,000 W	62 ft/s
F3 (−3 dB, no cabin gain)	32 Hz
Example box (outside)	31 1/2″ × 17 11/16″ × 12 7/16″

Open ported box in designer

Deeper: 3.18 ft³ (90 L) tuned to 31 Hz, 31 1/2″ × 17 11/16″ × 17″ 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 4 Ω
RMS power	1,000 W
Fs	33.6 Hz
Qts	0.47
Qes	0.545
Qms	3.26
Vas	1.88 ft³

Re (one coil)	≈ 3.4 Ω
Sd	127.4 in²
Xmax	0.51″
Vd	65.2 in³ calc.
Mms	403 g calc.
BL	23 T·m calc.
EBP	62 — sealed or ported calc.
Sensitivity, 1 W / 1 m	87.7 dB calc.

Mounting dimensions

Cutout diameter	13 3/4″
Mounting depth	7 11/16″
Overall diameter	15 9/16″

Cone area (Sd) calculated from Fs, Vas and Mms: 127.4 in².

“≈” 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/20120610175230/http://www.spldynamics.fi:80/products/subwoof

Other SPL Dynamics 15″ models

SPL Dynamics PRO-15D2 MK3 15″ · dual 2 Ω
SPL Dynamics PRO-15D2 MK4 15″ · dual 2 Ω
SPL Dynamics PRO-15D4 MK3 15″ · dual 4 Ω
SPL Dynamics PRO-15D4 MK4 15″ · dual 4 Ω
SPL Dynamics PRO-380D2 15″ · dual 2 Ω
SPL Dynamics PRO-380D4 15″ · dual 4 Ω
SPL Dynamics SPL-380D1A 15″ · dual 1 Ω
SPL Dynamics SPL-380D2 15″ · dual 2 Ω
SPL Dynamics XTR-380D2S 15″ · dual 2 Ω

Similar 15″ subwoofers from other brands

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

Sundown Audio Zv3-15 D1 1.45 ft³ sealed · 1.94 ft³ ported
CT Sounds MESO-15 D4 1.13 ft³ sealed · 2.01 ft³ ported
Sundown Audio Zv3-15 D2 1.45 ft³ sealed · 1.94 ft³ ported
Sundown Audio SAv3-15 D4 1.27 ft³ sealed · 3.00 ft³ ported
Rockville DESTROYER 15D1 1.57 ft³ sealed · 1.94 ft³ ported
CT Sounds MESO-15 D2 1.13 ft³ sealed · 2.01 ft³ ported

FAQ

What box does the SPL Dynamics XTR-380D4S need?

Recommended net volume: 1.17 ft³ sealed, 2.05 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 SPL Dynamics XTR-380D4S Thiele/Small specs?

Fs 33.6 Hz, Qts 0.47, Vas 1.88 ft³, Xmax 0.51″, Sd 127.4 in².

What is the SPL Dynamics XTR-380D4S mounting depth?

Mounting depth is 7 11/16″, cutout diameter 13 3/4″. The inside depth of the box must exceed the mounting depth by at least 1″.

How much power does the SPL Dynamics XTR-380D4S handle and how do I wire it?

RMS power rating: 1,000 W. Dual 4 Ω voice coils: series gives 8 Ω, parallel gives 2 Ω at the amp. Wiring for several subs and amp power — in the wiring calculator.