Lowther EX4 Drive Unit
| DC Resistance of Voice Coil | Re | 7.4 ohms |
| Free Air Resonance | Fo | 45 Hz |
| Emission Piston Area | Sd | 0.021M² |
| Equivalent Volume Suspension | Vas | 62.908 Ltrs |
| Suspension Compliance | Cms | 1005 u M/N |
| Mass of Cone | Mmd | 11.0 g |
| Mass of Moving Parts | Mms | 12.75 g |
| Force Factor | Bl | 10.233 T-M |
| Mechanical Q Factor | Qms | 3.781 |
| Electrical Q Factor | Qes | 0.248 |
| Total Q Factor | Qts | 0.233 |
| Voice Coil Inductance @ 1 kHz | Le | 28.071 uH |
| Reference Efficiency | No | 2.154% |
| Sound Pressure Level | SPL | 95.351 Db |

Lowther PM4A - Silver Coil - 15R
Lowther DX2 
