Diamond D315D4
15″ subwoofer · dual 4 Ω · 400 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, 400 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) | Boomy, with a bump · 1.09 |
|---|---|
| Fc | 46 Hz |
| F3 (−3 dB, no cabin gain) | 37 Hz |
| Example box (outside) | 31 1/2″ × 17 5/16″ × 13 1/8″ |
Ported
deeper, louder| Tuning (Fb) | 30 Hz |
|---|---|
| Port | slot 1 9/16 × 15 7/8″, 14 1/2″ long |
| Port velocity at 400 W | 58 ft/s |
| F3 (−3 dB, no cabin gain) | 31 Hz |
| Example box (outside) | 31 1/2″ × 17 5/16″ × 17 1/2″ |
Deeper: 5.19 ft³ (147 L) tuned to 34 Hz, 31 1/2″ × 17 5/16″ × 21 9/16″ 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 | 15″ |
|---|---|
| Voice coils | dual 4 Ω |
| RMS power | 400 W |
| Fs | 26 Hz |
| Qts | 0.61 |
| Qes | 0.681 |
| Qms | 6.02 |
| Vas | 6.60 ft³ |
| Re (one coil) | 3.2 Ω |
|---|---|
| Sd | 134.2 in² |
| Xmax | 0.47″ |
| Vd | 62.9 in³ calc. |
| Mms | 213 g calc. |
| BL | 12.8 T·m calc. |
| EBP | 38 — suits sealed calc. |
| Sensitivity, 1 W / 1 m | 88.8 dB calc. |
Mounting dimensions
| Cutout diameter | 13 7/16″ |
|---|---|
| Mounting depth | 7 11/16″ |
| Overall diameter | 15 5/16″ |
“≈” 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 Diamond 15″ models
- Diamond CM315D2 15″ · dual 2 Ω
- Diamond CM315D4 15″ · dual 4 Ω
- Diamond D315D2 15″ · dual 2 Ω
- Diamond D615D2 15″ · dual 2 Ω
- Diamond D615D4 15″ · dual 4 Ω
- Diamond D915D2 15″ · dual 2 Ω
- Diamond D915D4 15″ · dual 4 Ω
- Diamond H152 15″ · dual 2 Ω
- Diamond H154 15″ · dual 4 Ω
- Diamond HXP152 15″ · dual 2 Ω
- Diamond HXP154 15″ · dual 4 Ω
- Diamond M3151 15″ · 4 Ω
Similar 15″ subwoofers from other brands
Close in Fs, Qts and Vas — a box of similar volume will suit them.
- MTX Audio RTS15-04 2.97 ft³ sealed · 3.85 ft³ ported
- Rockford Fosgate Punch P115S4 (Stage-1, 2004) 3.04 ft³ sealed · 3.96 ft³ ported
- Fi Audio IB315 S4 2.86 ft³ sealed · 3.71 ft³ ported
- Bomber Bicho Papão 600W 4 Ohm (SW15BP-600-4) 3.04 ft³ sealed · 3.96 ft³ ported
- Fi Audio IB315 S2 2.86 ft³ sealed · 3.71 ft³ ported
- MTX Audio 7515-22 3.18 ft³ sealed · 3.00 ft³ ported
FAQ
What box does the Diamond D315D4 need?
Recommended net volume: 3.07 ft³ sealed, 3.99 ft³ ported tuned to 30 Hz — for one sub in a sedan at 400 W. Fit the box to your space and amp in the free calculator, with plans and a cut sheet.
What are the Diamond D315D4 Thiele/Small specs?
Fs 26 Hz, Qts 0.61, Vas 6.60 ft³, Xmax 0.47″, Sd 134.2 in².
What is the Diamond D315D4 mounting depth?
Mounting depth is 7 11/16″, cutout diameter 13 7/16″. The inside depth of the box must exceed the mounting depth by at least 1″.
How much power does the Diamond D315D4 handle and how do I wire it?
RMS power rating: 400 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.