Supro was Valco's own brand, and Valco built the same chassis for several makers, changing only the cosmetics and the logo — so the number, not the brand name, dates the amp. Up to 1964 a metal plate carries a V/X/T/G number from the Valco table; from 1964 a foil sticker with prefix 1 or 2 places the amp in 1964–68 or 1968.
The whole Valco group — Supro, National, Airline, Oahu and Gretsch — used a small metal plate on two brass nails with a number from the V/X/T/G table, which the Blue Book listing and a collector forum publication set out in agreement.
From 1964 the plate was replaced by a rectangular foil sticker with a numeric prefix: 1 for 1964–68 and 2 for 1968. Foil stickers are easily lost, which removes the dating key entirely.
Supro's S-numbers identify the chassis: S6400, S6420, S6424/S6524, S6450, S6497, S6511, S6606 and S6699 all appear in the reference listing with their power ratings and speakers.
The revived Supro brand builds current amps under its own numbering, with no continuity to the Valco serials.
| Series | Years | Rows | Era note |
|---|---|---|---|
| Valco metal number plate 1940-1964 (V / X / T / G prefixes) | 1940–1964 | 22 | |
| Post-1964 foil sticker: numeric prefix 1 or 2 | 1964–1968 | 2 |
10 Supro / Valco models are catalogued with their production years, specs and safety notes.
Browse the models →Because it is: Valco built the same chassis for several house brands, so the model number dates the chassis while the brand does not.
A prefix of 1 covers 1964–68 and a prefix of 2 marks 1968.
Two of the three published versions agree exactly, while the third shifts years and omits a row; only the agreeing pair is used.
Then EIA component codes are the only remaining witness.
Compiled from 150 published sources — the source library.