A born-on date is the date the maker wrote on the amp itself. Mesa/Boogie is the best-known case, and it is the only truly authoritative date those amplifiers carry.
Before 1990 most Mesa amps carry a specific month and year written by hand between the preamp tubes on the underside of the chassis, occasionally inside the chassis. Many also carry the initials of the technician who worked on them before final assembly.
From 2008–09 Mesa technicians initial and date the amps in plain view next to the serial decal, so the date no longer requires opening the amplifier.
The serial number cannot substitute for it: Mesa numbers are sequential inside a model, so a number identifies the model and its block rather than a year. Some models carry no born-on date at all.
The serial prefix table tells you which model family you have and where the number sits.
On the underside of the chassis, between the preamp tubes, on pre-1990 amps.
From 2008–09 the technician initials and date sit beside the serial decal.
A born-on date is written at assembly rather than at sale, so no correction is needed.
pre-1990 (handwritten), 2008-2009 onward (initials + date next to the serial decal) · 4 rows · confidence High · Mesa/Boogie — Amplitude archives
This is the only truly authoritative date for a Mesa and it is NOT derivable from the serial — it must be read off the amp. On some models it is absent entirely, and reaching it may require removing the chassis from the cabinet.
| Code as marked | Meaning | Source |
|---|---|---|
| dated between preamp tubes | pre-1990: handwritten month/year on the underside of the chassis; example model Mark IIB with tech initials and assembly date | Mesa/Boogie — Amplitude archives |
| serial decal near AC inlet | 1985 onwards — 'Post 1985 Guitar Amp heads and combos': the 0.75 x 1.5 in decal appears from the late 1980s; on almost all post-1988 combos and heads it is on the underside near the back-panel edge, usually on one side, | Mesa/Boogie — Amplitude archives |
| initials + date beside decal | 2008 onwards — since 2008-2009 techs initial and date the amp where the serial decal is visible | Mesa/Boogie — Amplitude archives |
| bass amps | recent Mesa bass amplification: decal on the rear panel near the IEC inlet, or on the back underside middle of the chassis; some head-cab units must be disassembled, and the number is also on the quality-control card | Mesa/Boogie — Amplitude archives |
1969-1979 · 3 rows · confidence Medium · Orange Field Guide — dating page
Present only on part of the production run; the tag dates inspection, which is extremely close to (but not identical with) completion.
| Code as marked | Meaning | Source |
|---|---|---|
| 15583 -> 6/7/1978 | July 1978 — OR80 Overdrive | Orange Field Guide — dating page |
| 16218 -> 9/7/79 | July 1979 — Overdrive Series II OR112M | Orange Field Guide — dating page |
| 1261 -> 16/1/78 | January 1978 — Hustler 125 | Orange Field Guide — dating page |
1963–1964 · 5 rows · confidence Medium · Vox AC30 — dateable amplifiers register — the 11xxx series
| Code as marked | Meaning | Source |
|---|---|---|
| N | Normal voicing | Vox AC30 — dateable amplifiers register — the 11xxx series |
| B | Bass voicing | Vox AC30 — dateable amplifiers register — the 11xxx series |
| T | Treble voicing | Vox AC30 — dateable amplifiers register — the 11xxx series |
| AMPLIFIER (without the VOX logo) | Vox AC30 — dateable amplifiers register — the 11xxx series | |
| 11167 | Vox AC30 — dateable amplifiers register — the 11xxx series |
Before 1990 it is written by hand between the preamp tubes on the underside of the chassis; from 2008–09 it sits next to the serial decal.
No. Mesa serials are sequential per model, so they identify the model and its block while the written date gives the year.
The term comes from Mesa. Other makers use QA stickers and date stamps, which are the same idea in a different form.