Ampeg dated its amps by serial number for most of its history, and its own knowledge base lays out the eras — including two eras that cannot be dated from the serial at all. The format changed with each owner, from the year-month-number scheme of the 1950s and early 1960s to the SLM and Line 6 formats of recent decades. Where the number fails, Ampeg's era features (panel graphics, switches, logo) and EIA component codes take over.
The earliest Ampeg amps carry no serial number that converts to a year, so EIA codes on transformers, speakers and pots are the only evidence. Ampeg documents this gap itself.
The YMMNNN format leads with the year digit, then the month and the sequence number. Because the year is a single digit, the same number can belong to 1953 and 1963, and the official guidance resolves those pairs from model history, circuit, cosmetics and the number structure.
A straight six-digit sequence runs to 092000, which the official table gives as the end of the era. Numbers inside the range convert to a year band.
Ampeg publishes no serial mapping for these years. Instead the era features table dates the amp from panel graphics, rocker switches and logo material, running from 1968 to 1979.
The SLM ten-character format runs 1985–2005 and encodes a letter year from 1988; a 17-character format follows for 2006–2019. Different owners assign the same letter different years, so the era has to be known first.
The current format carries month, year and week in the number. Documented codes run to 2023.
| Series | Years | Rows | Era note |
|---|---|---|---|
| No serial numbers before 1953 | 1946–1953 | 1 | 1946–1953 |
| YMMNNN — year digit, month, number | 1953–1965 | 10 | 1953 – mid 1965 |
| Sequential six-digit numbering | 1965–1969 | 5 | 1965–1969 (ends at 092000) |
| SLM — 10-character LLLCYMNNNN | 1988–2005 | 18 | 1985–2005 (letter years from 1988) |
| Loud Technologies: XXXXBBYMNNNN (2006 – 2018/19) | 2006–2019 | 14 | |
| Line 6 / YGG — (21)PPPPMYYWWXXXXXC | 2018–2023 | 6 | 2018 to today |
21 Ampeg models are catalogued with their production years, specs and safety notes.
Browse the models →In the 1953 to mid-1965 format the year is a single digit, so the same number can belong to two decades. The official method resolves the pair from the model, the circuit, the cosmetics and only then the number structure.
Ampeg publishes no serial mapping for 1970–79 or for 1981–85. The documented route is the era features table: panel graphics, rocker switches and logo material.
No. Ampeg states that lethal voltage remains inside tube amplifiers after power-off and singles out the SVT and V-series, so the chassis should only be opened by an experienced technician.
On the chassis or the rear panel, and on several models beside the mains inlet.
Compiled from 150 published sources — the source library.