SoundQubed HDX318 D1
18″ subwoofer · dual 1 Ω · 1,500 W RMS
Fs 27.6 HzQts 0.44Vas 5.95 ft³Xmax 1.42″
The published specs don’t add up:
- The published Xmax 1.42″ looks like max (mechanical) excursion, not linear: the excursion-limited power will read too high.
Recommended box
For a sedan, one sub, 1,500 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 | 2.51 ft³ (71 L) |
|---|---|
| Qtc | 0.80 |
| Fc | 51 Hz |
| F3 (−3 dB, no cabin gain) | 48 Hz |
| Example box (outside) | 19 11/16″ × 19 11/16″ × 15 7/8″ |
Ported
| Net volume | 7.27 ft³ (206 L) |
|---|---|
| Tuning (Fb) | 29 Hz |
| Port | slot 4 1/8 × 19 1/16″, 27 1/16″ long |
| Port velocity at 1,500 W | 65 ft/s |
| F3 (−3 dB, no cabin gain) | 27 Hz |
| Example box (outside) | 31 1/2″ × 20 1/2″ × 28 3/8″ |
Thiele/Small parameters
| Fs | 27.6 Hz |
|---|---|
| Qts | 0.44 |
| Qes | 0.472 |
| Qms | 5.78 |
| Vas | 5.95 ft³ |
| Re (one coil) | ≈ 0.85 Ω |
| Sd | 187.6 in² |
| Xmax | 1.42″ |
| Vd | 265.8 in³ calc. |
| Mms | 409 g calc. |
| BL | 11.3 T·m calc. |
| EBP | 58 — sealed or ported calc. |
| Sensitivity, 1 W / 1 m | 90.8 dB calc. |
General
| Size | 18″ |
|---|---|
| Voice coils | dual 1 Ω |
| RMS power | 1,500 W |
Mounting dimensions
| Cutout diameter | 16 9/16″ |
|---|---|
| Mounting depth | 10 1/2″ |
“≈” 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 SoundQubed 18″ models
- SoundQubed HDS3.218 D2 18″ · dual 2 Ω
- SoundQubed HDS3.218 D4 18″ · dual 4 Ω
- SoundQubed HDX318 D2 18″ · dual 2 Ω
- SoundQubed HDX418 D1 18″ · dual 1 Ω