| System | Period | Rows | What it dates |
|---|---|---|---|
| EIA component codes (speakers, transformers, pots, capacitors) | whole vintage era | 16 | |
| Era features 1968–1979 (panel, switches, logo, knobs) | 1968–1979 | 10 | |
| Resolving an ambiguous serial | 1953–1965 digit pairs | 9 | |
| Safety warning (model pages) | all eras | 1 |
SVT / SVT-CL / SVT Pro, V-4, V-4B, V-series — read the number from the outside. Tube amps of this family store lethal voltages after they are switched off; the maker's own service text says the chassis should not be opened by anyone without experience.