ER-139
| Brand | Electrostatic Research Corporation |
| Designer | Arthur A. Janszen, Charles McShane |
| Function | Speaker |
| Produced | 1975 |
| Country | United States |
| Form Factor | Floorstanding |
| Signal Path | Passive Hardware |
| Treble | Electrostatic Transducers (x8) |
| Midrange/Bass | 10" Paper Cone |
| Finish | Walnut |
| MSRP (1975) | $179.90/pr (With Cover: $199.99/pr) |
| Connections |
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