Diamond D312D4
12″ 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) | Tight and punchy · 0.80 |
|---|---|
| Fc | 48 Hz |
| F3 (−3 dB, no cabin gain) | 45 Hz |
| Example box (outside) | 14 9/16″ × 14 9/16″ × 20 1/8″ |
Ported
deeper, louder| Tuning (Fb) | 34 Hz |
|---|---|
| Port | slot 1 9/16 × 14 5/16″, 32 1/8″ long |
| Port velocity at 400 W | 45 ft/s |
| F3 (−3 dB, no cabin gain) | 35 Hz |
| Example box (outside) | 22 1/8″ × 15 3/4″ × 13 3/4″ |
Deeper: 3.18 ft³ (90 L) tuned to 32 Hz, 31 1/2″ × 15 3/4″ × 16 1/8″ 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 | 400 W |
| Fs | 34 Hz |
| Qts | 0.56 |
| Qes | 0.636 |
| Qms | 4.97 |
| Vas | 1.81 ft³ |
| Re (one coil) | 3.2 Ω |
|---|---|
| Sd | 82.3 in² |
| Xmax | 0.47″ |
| Vd | 38.6 in³ calc. |
| Mms | 172 g calc. |
| BL | 13.6 T·m calc. |
| EBP | 53 — sealed or ported calc. |
| Sensitivity, 1 W / 1 m | 87 dB calc. |
Mounting dimensions
| Cutout diameter | 11 1/4″ |
|---|---|
| Mounting depth | 6 5/8″ |
| 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
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 D612D2 12″ · dual 2 Ω
- Diamond D612D4 12″ · dual 4 Ω
- Diamond D912D2 12″ · dual 2 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.
- Kenwood KFC-W12PS 1.80 ft³ sealed · 1.52 ft³ ported
- Swat MAS-12 v.2 1.55 ft³ sealed · 1.48 ft³ ported
- Audiobahn AW1200V 1.59 ft³ sealed · 1.48 ft³ ported
- Alpine SWS-12D4 (Type-S) 1.55 ft³ sealed · 1.24 ft³ ported
- Phoenix Gold SXT12D2 (slim, DVC 2 ohm) 1.73 ft³ sealed · 1.59 ft³ ported
- Ground Zero GZTW 30TX (2x2 Ohm) 1.52 ft³ sealed · 1.55 ft³ ported
FAQ
What box does the Diamond D312D4 need?
Recommended net volume: 1.77 ft³ sealed, 1.45 ft³ ported tuned to 34 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 D312D4 Thiele/Small specs?
Fs 34 Hz, Qts 0.56, Vas 1.81 ft³, Xmax 0.47″, Sd 82.3 in².
What is the Diamond D312D4 mounting depth?
Mounting depth is 6 5/8″, cutout diameter 11 1/4″. The inside depth of the box must exceed the mounting depth by at least 1″.
How much power does the Diamond D312D4 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.