Sigma
| Brand | STR |
| Manufacturer | Sound Technology Research |
| Function | Speaker |
| Produced | 1974 |
| Country | United States |
| Form Factor | Floorstanding |
| Signal Path | Analog Hardware |
| Dimensions | 39.4 × 79.4 × 40.4 cm (W × H × D) |
| Weight | 85lbs |
| Frequency Response | 30Hz-20kHz ±5dB |
| Treble | 1.5" Piezo (x3) |
| Midrange | 4.5" Paper Cone |
| Bass | 12" Paper Cone |
| Impedance (Nominal) | 8Ω |
| Crossover Frequencies | 1kHz, 4kHz |
| Recommended Amplifier Power | 15-200W |
| Power Handling | 200W |
| Enclosure Type | Bass Reflex |
| Finish | Walnut |
| MSRP (1974) | $598 (Per Pair) |