Rockford Fosgate Punch HX2 RFD3218
18″ subwoofer · dual 4 Ω · 1,000 W RMS
Fs 24 HzQts 0.46Vas 7.03 ft³Xmax 0.75″
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
| Net volume | 3.35 ft³ (95 L) |
|---|---|
| Qtc | 0.80 |
| Fc | 42 Hz |
| F3 (−3 dB, no cabin gain) | 40 Hz |
| Example box (outside) | 31 1/2″ × 20 1/16″ × 12 5/8″ |
Ported
| Net volume | 6.78 ft³ (192 L) |
|---|---|
| Tuning (Fb) | 28 Hz |
| Port | slot 3 1/8 × 18 11/16″, 23 1/4″ long |
| Port velocity at 1,000 W | 65 ft/s |
| F3 (−3 dB, no cabin gain) | 26 Hz |
| Example box (outside) | 31 1/2″ × 20 1/16″ × 26″ |
Thiele/Small parameters
| Fs | 24 Hz |
|---|---|
| Qts | 0.46 |
| Qes | 0.49 |
| Qms | 6.39 |
| Vas | 7.03 ft³ |
| Re (one coil) | 4.24 Ω |
| Sd | 175 in² |
| Xmax | 0.75″ |
| Vd | 130.9 in³ calc. |
| Mms | 399 g calc. |
| BL | 22.8 T·m calc. |
| EBP | 49 — suits sealed calc. |
| Sensitivity, 1 W / 1 m | 89.5 dB calc. |
General
| Size | 18″ |
|---|---|
| Voice coils | dual 4 Ω |
| RMS power | 1,000 W |
Mounting dimensions
| Cutout diameter | 16 1/4″ |
|---|---|
| Mounting depth | 9 3/16″ |
| Overall diameter | 18 1/16″ |
Judging by its value, the published Re is for both coils in parallel — converted to per coil.
“≈” 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.