Ultra U-18 18" 2500w Car Audio Subwoofer
The Colossal Sounds Ultra 18" subwoofer combines high-output SPL performance with accurate daily-driver sound. This 18-inch ground-pounder is designed for strong, efficient output across a wide range of music.
Its cooling-focused motor assembly, non-pressed paper cone, carbon-fiber dust cap, Nomex spider pack, heavy-duty sewn-in lead wires, and cast-aluminum basket are engineered for durability, cone control, and consistent daily output.
Driver data
Technical information
Published specifications and enclosure guidance for planning your system.
General specifications
| RMS power handling | 2,500 Watts |
|---|---|
| Peak power handling | 5,000 Watts |
| Voice coil size | 3" |
| Voice coil configuration | Dual 1 Ω | Dual 2 Ω |
| XMAX (one way) | 33 mm |
| Product weight | 65 lbs |
| Build lead time | Approximately 2 weeks |
Thiele/Small (T/S) parameters
Measurement condition: Ultra 18" D2 — 3-hour break-in period
| Re — DC resistance | 3.0912 Ω |
|---|---|
| Fs — Free-air resonance | 26.1205 Hz |
| Qes — Electrical Q | 0.5463 |
| Qms — Mechanical Q | 5.9407 |
| Qts — Total Q | 0.5003 |
| Le — Voice coil inductance | 2.4249 mH at 1 kHz |
| Sd — Effective piston area | 125,695.1094 mm² (194.8278 in²) |
| Vas — Equivalent compliance volume | 185.2033 L (6.5404 ft³) |
| BL — Motor force factor | 20.4412 N/A |
| Mms — Moving mass | 449.9150 g |
| Cms — Mechanical compliance | 82.5178 µm/N |
| Sensitivity | 89.5594 dB @ 1 W/1 m |
Enclosure recommendations
| Recommended ported enclosure volume | 5–7 cu ft |
|---|---|
| Ported tuning | 31 Hz |
| Bandpass sealed-chamber volume | 2.5–4 cu ft |
The manufacturer lists this sealed-chamber volume for bandpass applications only.
Send us your subwoofer model, available space and performance goals.
Technical data source: View manufacturer specifications