Diamond D122
12″ subwoofer · dual 2 Ω · 200 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, 200 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 | 44 Hz |
| F3 (−3 dB, no cabin gain) | 41 Hz |
| Example box (outside) | 14 3/16″ × 14 3/16″ × 18 11/16″ |
Ported
deeper, louder| Tuning (Fb) | 30 Hz |
|---|---|
| Port | slot 1 9/16 × 14 5/16″, 25 1/4″ long |
| Port velocity at 200 W | 40 ft/s |
| F3 (−3 dB, no cabin gain) | 29 Hz |
| Example box (outside) | 31 1/2″ × 15 3/4″ × 12 7/8″ |
Deeper: 3.00 ft³ (85 L) tuned to 29 Hz, 31 1/2″ × 15 3/4″ × 15 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 | 200 W |
| Fs | 24 Hz |
| Qts | 0.44 |
| Qes | 0.51 |
| Qms | 3.3 |
| Vas | 3.47 ft³ |
| Re (one coil) | 1.8 Ω |
|---|---|
| Sd | 77.5 in² |
| Xmax | 0.32″ |
| Vd | 24.7 in³ calc. |
| Mms | 158 g calc. |
| BL | 9.2 T·m calc. |
| EBP | 47 — suits sealed calc. |
| Sensitivity, 1 W / 1 m | 86.3 dB calc. |
Mounting dimensions
| Cutout diameter | 11 1/8″ |
|---|---|
| Mounting depth | 5 15/16″ |
| Overall diameter | 12 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
Other Diamond 12″ models
- Diamond CM312D2 12″ · dual 2 Ω
- Diamond CM312D4 12″ · dual 4 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 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.
- JBL GTO1202D 1.52 ft³ sealed · 2.44 ft³ ported
- Infinity Kappa Perfect 12.1 1.52 ft³ sealed · 2.44 ft³ ported
- Focal SUB 12 (SVC 4 ohm) 1.41 ft³ sealed · 2.15 ft³ ported
- JL Audio 12W3v2-D2 1.70 ft³ sealed · 2.40 ft³ ported
- JL Audio 12W3v2-D4 1.41 ft³ sealed · 2.40 ft³ ported
- Morel Ultimo Titanium 124 (SVC 4 ohm) 1.66 ft³ sealed · 2.15 ft³ ported
FAQ
What box does the Diamond D122 need?
Recommended net volume: 1.52 ft³ sealed, 2.30 ft³ ported tuned to 30 Hz — for one sub in a sedan at 200 W. Fit the box to your space and amp in the free calculator, with plans and a cut sheet.
What are the Diamond D122 Thiele/Small specs?
Fs 24 Hz, Qts 0.44, Vas 3.47 ft³, Xmax 0.32″, Sd 77.5 in².
What is the Diamond D122 mounting depth?
Mounting depth is 5 15/16″, 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 D122 handle and how do I wire it?
RMS power rating: 200 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.