URAL Bulava 18 (2+2)
18″ subwoofer · dual 2 Ω · 900 W RMS
Fs 25.8 HzQts 0.72Vas 5.81 ft³Xmax 1.18″
Recommended box
For a sedan, one sub, 900 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 | 4.20 ft³ (119 L) |
|---|---|
| Qtc | 1.11 |
| Fc | 40 Hz |
| F3 (−3 dB, no cabin gain) | 31 Hz |
| Example box (outside) | 31 1/2″ × 20 7/8″ × 14 11/16″ |
Ported
| Net volume | 7.13 ft³ (202 L) |
|---|---|
| Tuning (Fb) | 30 Hz |
| Port | slot 2 3/4 × 19 7/16″, 16 1/4″ long |
| Port velocity at 900 W | 65 ft/s |
| F3 (−3 dB, no cabin gain) | 26 Hz |
| Example box (outside) | 31 1/2″ × 20 7/8″ × 25 1/8″ |
Thiele/Small parameters
| Fs | 25.8 Hz |
|---|---|
| Qts | 0.72 |
| Qes | 0.83 |
| Qms | 5.36 |
| Vas | 5.81 ft³ |
| Re (one coil) | ≈ 1.7 Ω |
| Sd | 183.8 in² |
| Xmax | 1.18″ |
| Vd | 217 in³ calc. |
| Mms | 461 g calc. |
| BL | 12.4 T·m calc. |
| EBP | 31 — suits sealed calc. |
| Sensitivity, 1 W / 1 m | 87.3 dB calc. |
General
| Size | 18″ |
|---|---|
| Voice coils | dual 2 Ω |
| RMS power | 900 W |
Mounting dimensions
| Cutout diameter | 16 13/16″ |
|---|---|
| Mounting depth | 8″ |
| Overall diameter | 18 9/16″ |
Cone area (Sd) calculated from Fs, Vas and Mms: 183.8 in².
“≈” 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 URAL 18″ models
- URAL Decibel 18 (1+1) 18″ · dual 1 Ω
- URAL Patriot 18 (2+2) 18″ · dual 2 Ω
- URAL Pobeda 18 (2+2) 18″ · dual 2 Ω