SPL Dynamics XTR-300D4
12″ subwoofer · dual 4 Ω · 750 W RMS
| 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 |
Recommended box
For a sedan, one sub, 750 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| Bass character (Qtc) | Flat and accurate · 0.71 |
|---|---|
| Fc | 57 Hz |
| F3 (−3 dB, no cabin gain) | 59 Hz |
| Example box (outside) | 14 3/16″ × 14 3/16″ × 10 7/16″ |
Ported
deeper, louder| Tuning (Fb) | 34 Hz |
|---|---|
| Port | slot 2 9/16 × 14 5/16″, 29 13/16″ long |
| Port velocity at 750 W | 65 ft/s |
| F3 (−3 dB, no cabin gain) | 31 Hz |
| Example box (outside) | 31 1/2″ × 15 3/4″ × 14 11/16″ |
Deeper: 1.77 ft³ (50 L) tuned to 33 Hz, 31 1/2″ × 15 3/4″ × 12 7/16″ outside — a bigger box with flatter deep bass. Open in the calculator
Projects with this subwoofer
Boxes that users designed and published: plans, cut sheet and response graph.
Thiele/Small parameters
| Size | 12″ |
|---|---|
| Voice coils | dual 4 Ω |
| RMS power | 750 W |
| Fs | 31.1 Hz |
| Qts | 0.39 |
| Qes | 0.434 |
| Qms | 4.01 |
| Vas | 1.72 ft³ |
| Re (one coil) | 2.9 Ω |
|---|---|
| Sd | 82.6 in² |
| Xmax | 0.47″ |
| Vd | 39 in³ calc. |
| Mms | 216 g calc. |
| BL | 16.8 T·m calc. |
| EBP | 72 — sealed or ported calc. |
| Sensitivity, 1 W / 1 m | 87.3 dB calc. |
Mounting dimensions
| Cutout diameter | 11 3/16″ |
|---|---|
| Mounting depth | 6 11/16″ |
| Overall diameter | 12 13/16″ |
Cone area (Sd) calculated from Fs, Vas and Mms: 82.6 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/20120610030002/http://www.spldynamics.fi:80/products/subwoof
- web.archive.org/web/20071214084355/http://www.spldynamics.fi:80/xtr-sub/xtr-300d
Other SPL Dynamics 12″ models
- SPL Dynamics PRO-12D2 MK3 12″ · dual 2 Ω
- SPL Dynamics PRO-12D2 MK4 12″ · dual 2 Ω
- SPL Dynamics PRO-12D4 MK3 12″ · dual 4 Ω
- SPL Dynamics PRO-12D4 MK4 12″ · dual 4 Ω
- SPL Dynamics PRO-300D2 12″ · dual 2 Ω
- SPL Dynamics PRO-300D4 12″ · dual 4 Ω
- SPL Dynamics SPL-300D1A 12″ · dual 1 Ω
- SPL Dynamics SPL-300D2 12″ · dual 2 Ω
- SPL Dynamics SW-300D2 12″ · dual 2 Ω
- SPL Dynamics SW-300D4 12″ · dual 4 Ω
- SPL Dynamics V-12S 12″ · 4 Ω
- SPL Dynamics V-12S4 12″ · 4 Ω
Similar 12″ subwoofers from other brands
Close in Fs, Qts and Vas — a box of similar volume will suit them.
- SoundQubed HDS2.212 D2 0.71 ft³ sealed · 2.33 ft³ ported
- SoundQubed HDS2.212 D4 0.71 ft³ sealed · 2.33 ft³ ported
- Audiobahn AW120XS 0.71 ft³ sealed · 2.26 ft³ ported
- DLS RCW12 0.71 ft³ sealed · 2.26 ft³ ported
- Hertz Hi-Energy HX 300 D (DVC 4+4 ohm) 0.71 ft³ sealed · 1.24 ft³ ported
- Audiobahn AW120Q 0.64 ft³ sealed · 2.08 ft³ ported
FAQ
What box does the SPL Dynamics XTR-300D4 need?
Recommended net volume: 0.74 ft³ sealed, 2.44 ft³ ported tuned to 34 Hz — for one sub in a sedan at 750 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-300D4 Thiele/Small specs?
Fs 31.1 Hz, Qts 0.39, Vas 1.72 ft³, Xmax 0.47″, Sd 82.6 in².
What is the SPL Dynamics XTR-300D4 mounting depth?
Mounting depth is 6 11/16″, cutout diameter 11 3/16″. The inside depth of the box must exceed the mounting depth by at least 1″.
How much power does the SPL Dynamics XTR-300D4 handle and how do I wire it?
RMS power rating: 750 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.