Diamond D912D2
12″ subwoofer · dual 2 Ω · 800 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, 800 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 · 0.73 |
|---|---|
| Fc | 47 Hz |
| F3 (−3 dB, no cabin gain) | 48 Hz |
| Example box (outside) | 14 3/16″ × 14 3/16″ × 10 7/16″ |
Ported
deeper, louder| Tuning (Fb) | 34 Hz |
|---|---|
| Port | slot 1 9/16 × 14 5/16″, 39 9/16″ long |
| Port velocity at 800 W | 71 ft/s |
| F3 (−3 dB, no cabin gain) | 30 Hz |
| Example box (outside) | 19 1/8″ × 15 3/4″ × 15 3/16″ |
Deeper: 1.70 ft³ (48 L) tuned to 28 Hz, 31 1/2″ × 15 3/4″ × 12 5/16″ 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 2 Ω |
| RMS power | 800 W |
| Fs | 33 Hz |
| Qts | 0.51 |
| Qes | 0.6 |
| Qms | 3.5 |
| Vas | 0.78 ft³ |
| Re (one coil) | 1.93 Ω |
|---|---|
| Sd | 76 in² |
| Xmax | 0.94″ |
| Vd | 71.8 in³ calc. |
| Mms | 360 g calc. |
| BL | 15.5 T·m calc. |
| EBP | 55 — sealed or ported calc. |
| Sensitivity, 1 W / 1 m | 83.2 dB calc. |
Mounting dimensions
| Cutout diameter | 11 1/8″ |
|---|---|
| Mounting depth | 8″ |
| Overall diameter | 12 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/20060311053338/http://www.diamondaudio.com/products/pdfs/D9%
- web.archive.org/web/20070320154300/http://www.diamondaudio.com:80/PDF/current/D9
Other Diamond 12″ models
- Diamond CM312D2 12″ · dual 2 Ω
- Diamond CM312D4 12″ · dual 4 Ω
- Diamond D122 12″ · dual 2 Ω
- Diamond D124 12″ · dual 4 Ω
- Diamond D312D2 12″ · dual 2 Ω
- Diamond D312D4 12″ · dual 4 Ω
- Diamond D612D2 12″ · dual 2 Ω
- Diamond D612D4 12″ · dual 4 Ω
- Diamond D912D4 12″ · dual 4 Ω
- Diamond DE122 12″ · dual 2 Ω
- Diamond DE124 12″ · dual 4 Ω
- Diamond DES122 12″ · dual 2 Ω
Similar 12″ subwoofers from other brands
Close in Fs, Qts and Vas — a box of similar volume will suit them.
- Sundown Audio SA Classic 12 D2 0.60 ft³ sealed · 1.77 ft³ ported
- Swat HLG-P12D1 0.92 ft³ sealed · 1.20 ft³ ported
- CT Sounds STRATO-12 D4 0.72 ft³ sealed · 1.52 ft³ ported
- Ascendant Audio Havoc 12 D1 0.67 ft³ sealed · 1.20 ft³ ported
- Sundown Audio SA Classic 12 D4 0.60 ft³ sealed · 1.77 ft³ ported
- Sundown Audio Zv5-12 D1 1.06 ft³ sealed · 1.06 ft³ ported
FAQ
What box does the Diamond D912D2 need?
Recommended net volume: 0.74 ft³ sealed, 1.20 ft³ ported tuned to 34 Hz — for one sub in a sedan at 800 W. Fit the box to your space and amp in the free calculator, with plans and a cut sheet.
What are the Diamond D912D2 Thiele/Small specs?
Fs 33 Hz, Qts 0.51, Vas 0.78 ft³, Xmax 0.94″, Sd 76 in².
What is the Diamond D912D2 mounting depth?
Mounting depth is 8″, cutout diameter 11 1/8″. The inside depth of the box must exceed the mounting depth by at least 1″.
How much power does the Diamond D912D2 handle and how do I wire it?
RMS power rating: 800 W. Dual 2 Ω voice coils: series gives 4 Ω, parallel gives 1 Ω at the amp. Wiring for several subs and amp power — in the wiring calculator.