Wide-Range Constant-Charge Electrostatic Loudspeaker
| Brand | Acoustical, Quad |
| Manufacturer | Acoustical Manufacturing Co. Ltd. |
| Function | Speaker |
| Produced | 1957 |
| Country | United Kingdom |
| Form Factor | Floorstanding |
| Signal Path | Analog Hardware |
| Dimensions | 83.8 × 63.5 × 7.6 cm (W × H × D) |
| Power | 6W |
| Driver | Full-Range Push-Pull Electrostatic (Mass: 7x10⁻⁴g/cm²) |
| MSRP (1957) | £35 |
| Notes | Immediate predecessor to ESL-57. |