Diamond CM315D4
15″ subwoofer · dual 4 Ω
| 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, 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| Bass character (Qtc) | Boomy, with a bump · 0.98 |
|---|---|
| Fc | 43 Hz |
| F3 (−3 dB, no cabin gain) | 36 Hz |
| Example box (outside) | 31 1/2″ × 17 11/16″ × 11 7/8″ |
Ported
deeper, louder| Tuning (Fb) | 33 Hz |
|---|---|
| Port | slot 1 9/16 × 16 5/16″, 22 7/8″ long |
| Port velocity at 300 W | 42 ft/s |
| F3 (−3 dB, no cabin gain) | 32 Hz |
| Example box (outside) | 31 1/2″ × 17 11/16″ × 11 7/8″ |
Deeper: 4.73 ft³ (134 L) tuned to 31 Hz, 31 1/2″ × 17 11/16″ × 19 11/16″ 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 | — |
| Fs | 30 Hz |
| Qts | 0.69 |
| Qes | 0.75 |
| Qms | 8 |
| Vas | 2.92 ft³ |
| Re (one coil) | 3.2 Ω |
|---|---|
| Sd | 122.5 in² |
| Xmax | 0.47″ |
| Vd | 57.9 in³ calc. |
| Mms | 301 g calc. |
| BL | 15.6 T·m calc. |
| EBP | 40 — suits sealed calc. |
| Sensitivity, 1 W / 1 m | 86.7 dB calc. |
Mounting dimensions
| Cutout diameter | 13 15/16″ |
|---|---|
| Mounting depth | 7 3/8″ |
| Overall diameter | 15 3/8″ |
“≈” 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/20070830083842/http://www.diamondaudio.com/PDF/archive/CM3/C
- web.archive.org/web/20050405075111/http://www.diamondaudio.com:80/products/pdfs/
Other Diamond 15″ models
- Diamond CM315D2 15″ · dual 2 Ω
- Diamond D315D2 15″ · dual 2 Ω
- Diamond D315D4 15″ · dual 4 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.
- Memphis Car Audio M71512 (M7 15", 1ohm setting) 3.11 ft³ sealed · 2.30 ft³ ported
- Quantum Audio QW3000/15D4 2.93 ft³ sealed · 2.30 ft³ ported
- Cerwin-Vega Mobile VMAX154 (VMAX 15" DVC 4ohm) 2.83 ft³ sealed · 1.80 ft³ ported
- Audioque SDC2.515 D4 2.83 ft³ sealed · 2.51 ft³ ported
- URAL AS-D15.3TD2 (2+2) 2.83 ft³ sealed · 2.22 ft³ ported
- URAL AS-D15.3TD4 (4+4) 2.83 ft³ sealed · 2.22 ft³ ported
FAQ
What box does the Diamond CM315D4 need?
Recommended net volume: 2.79 ft³ sealed, 2.33 ft³ ported tuned to 33 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 Diamond CM315D4 Thiele/Small specs?
Fs 30 Hz, Qts 0.69, Vas 2.92 ft³, Xmax 0.47″, Sd 122.5 in².
What is the Diamond CM315D4 mounting depth?
Mounting depth is 7 3/8″, cutout diameter 13 15/16″. The inside depth of the box must exceed the mounting depth by at least 1″.