Diamond D915D4
15″ subwoofer · dual 4 Ω · 1,000 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, 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| Bass character (Qtc) | Tight and punchy · 0.80 |
|---|---|
| Fc | 45 Hz |
| F3 (−3 dB, no cabin gain) | 43 Hz |
| Example box (outside) | 17 5/16″ × 17 5/16″ × 11 15/16″ |
Ported
deeper, louder| Tuning (Fb) | 30 Hz |
|---|---|
| Port | slot 1 15/16 × 16 11/16″, 41 5/16″ long |
| Port velocity at 1,000 W | 61 ft/s |
| F3 (−3 dB, no cabin gain) | 29 Hz |
| Example box (outside) | 23 13/16″ × 18 1/8″ × 16 3/4″ |
Deeper: 4.38 ft³ (124 L) tuned to 25 Hz, 31 1/2″ × 18 1/8″ × 22 1/16″ 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 | 1,000 W |
| Fs | 26 Hz |
| Qts | 0.46 |
| Qes | 0.53 |
| Qms | 3.7 |
| Vas | 2.65 ft³ |
| Re (one coil) | 3.1 Ω |
|---|---|
| Sd | 122.5 in² |
| Xmax | 1.02″ |
| Vd | 125.3 in³ calc. |
| Mms | 442 g calc. |
| BL | 20.5 T·m calc. |
| EBP | 49 — suits sealed calc. |
| Sensitivity, 1 W / 1 m | 86 dB calc. |
Mounting dimensions
| Cutout diameter | 14 3/16″ |
|---|---|
| Mounting depth | 9 1/2″ |
| Overall diameter | 15 9/16″ |
“≈” 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
- web.archive.org/web/20060311053338/http://www.diamondaudio.com/products/pdfs/D9%
- web.archive.org/web/20070320154300/http://www.diamondaudio.com:80/PDF/current/D9
Other Diamond 15″ models
- Diamond CM315D2 15″ · dual 2 Ω
- Diamond CM315D4 15″ · dual 4 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 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.
- Fi Audio BTL4 15 D1 1.27 ft³ sealed · 2.01 ft³ ported
- Fi Audio BTL4 15 D2 1.27 ft³ sealed · 2.01 ft³ ported
- Fi Audio SP4 15 D1 1.62 ft³ sealed · 2.01 ft³ ported
- Fi Audio SP415 v2.1 D1 1.59 ft³ sealed · 2.01 ft³ ported
- Fi Audio SP4 15 D2 1.62 ft³ sealed · 2.01 ft³ ported
- Fi Audio SP415 v2.1 D2 1.59 ft³ sealed · 2.01 ft³ ported
FAQ
What box does the Diamond D915D4 need?
Recommended net volume: 1.36 ft³ sealed, 2.12 ft³ ported tuned to 30 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 Diamond D915D4 Thiele/Small specs?
Fs 26 Hz, Qts 0.46, Vas 2.65 ft³, Xmax 1.02″, Sd 122.5 in².
What is the Diamond D915D4 mounting depth?
Mounting depth is 9 1/2″, cutout diameter 14 3/16″. The inside depth of the box must exceed the mounting depth by at least 1″.
How much power does the Diamond D915D4 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.