Tri-Channel Mk. 4
| Brand | Sound Sales |
| Manufacturer | Sound Sales Ltd. |
| Function | Speaker |
| Produced | 195?-1957 |
| Country | United Kingdom |
| Form Factor | Floorstanding |
| Signal Path | Analog Hardware |
| Dimensions | 109.2 × 78.7 × 63.5 cm (W × H × D) |
| Weight | 202lbs |
| Frequency Response | 25Hz-27kHz |
| Treble | Electrostatic |
| Midrange | 12" Paper Cone (Sound Sales Auditorium) |
| Bass | 12" Paper Cone (x2) (Sound Sales Auditorium) |
| Amplification (Treble) | 4W |
| Amplification (Midrange) | 8-12W |
| Amplification (Bass) | 20-30W |
| Total Amplification | 45W |
| Output Tube (Treble) | LN309 |
| Output Tube (Midrange) | EL34 |
| Output Tube (Bass) | EL84 |
| Enclosure Type | Labyrinth, Bass Reflex |
| MSRP (1957) | £115 |
| Notes | Actively tri-amplified |