400S
| Brand | Advent |
| Manufacturer | ESMARK Company |
| Function | Speaker |
| Produced | 1980 |
| Country | United States |
| Form Factor | Bookshelf / Stand Mounted |
| Signal Path | Passive Hardware |
| Dimensions | 27.9 × 16.8 × 15.2 cm (W × H × D) |
| Weight | 5.5lbs |
| Driver | 5.25" Paper Cone |
| Impedance (Nominal) | 8Ω |
| Enclosure Type | Sealed |
| Enclosure Construction | Polystyrene |
| Finish | White |
| MSRP (1980) | $35 |
| Notes | Updated Model 400 |