How do I read a Revox A77 serial?

The prefix selects the build: S = Switzerland, G = Germany, each with its own scale (S 054–18,080 is 1967–69; G 145,100–289,836 is 1974–77). The prefix is the place of assembly, not a version.

Where is the exact date on an A77?

Month and year are stamped on the motor rotors — the closest thing to a build date. Reaching them means dismantling the deck, so the archive reports the serial bracket first.

Can I date a B77 or PR99?

The B77 is bracketed in two halves (1–100,000 = 1977–1980, then to 1989); the PR99 has no public serial dating at all.

The maker's archive

Revox (Willi Studer) hi-fi.

Revox is the tape case in this archive. The A77 is documented by version, with serial ranges that separate the Swiss-built (prefix S) and German-built (prefix G) machines, and by the month/year stamp on the motor rotors — the only place where an exact date survives.

Country: Switzerland
Active since: 1948
Coverage: 1967–1989 · 12 serial ranges
Dating tier: Serial numbers
In the archive: 4 series · 19 code systems · 10 models
Years documented: 1967–1989

What dates this maker

A77 — serial ranges by version (Mk I to Mk IV), Swiss S and German G running as parallel streams.
Motor rotor stamp — month and year, the closest thing to a build date on these machines.
B77 — the change of 1980 is tied to serial 100000; PR99 and G36 are documented more thinly.

Watch out

The S and G prefixes mean where a machine was assembled, not which version it is: one version has two ranges.
A number cannot be read without its prefix, and the prefix cannot be read without the model.

Series	Years	Rows
Revox A77 — machines assembled in Switzerland (prefix S)	1967–1977	4
Revox A77 — machines assembled in Löffingen (prefix G)	1967–1977	4
Revox B77	1977–1989	2
Revox G36 (revisions by serial number)	—	2

A77 exact build date: month+year stamped on the reel-motor rotorsA77, 1967-1977 · 1 rows · High confidence

A77 Mark I-IV: serial brackets, dates and the features that prove each Mark1967-1977 · 7 rows · High confidence

A77 factory changes by serial number (a build bracket from internal parts)1967-1977 · 6 rows · High confidence

B77: 1977-1989, changed from 1980 and from serial number 100,0001977-1989 · 3 rows · Medium confidence

G36: modifications effective from serial numbers 36,500 and 58,000G36 (late 1950s-1960s) · 2 rows · High confidence

Hunts capacitor date code (WHITSUNDAY)1950s-1969 (Hunts taken over by Erie in the late 1960s, probably 1969) · 25 rows · Medium confidence

British year-letter date codes (TCC, Dubilier, Radiospares, Woden, Welwyn)1950s-1960s · 4 rows · Medium confidence

Mullard 'mustard' capacitor date codelate 1963 onwards (used occasionally in late 1963, more frequently from mid 1964) · 3 rows · Medium confidence

Egen potentiometer date code1960-1964 (year letters documented by the source) · 2 rows · Medium confidence

EIA component source/date codeswhole vintage period · 1 rows · High confidence

Safety warnings that apply to any vintage valve hi-fiwhole vintage period · 4 rows · High confidence

Japanese electrolytic capacitor date codes - the shared YYWW mechanicdocumented samples 1993-2023; no maker states when a format started or ended · 0 rows · Medium confidence

Nippon Chemi-Con date code (year digit + bracketed character)2000s production (the repair page was published November 2005) · 2 rows · Low confidence

Nichicon date code (plant letter + YYWW)1990s-2010s (documented 1993 and 2013 samples, same format) · 4 rows · Medium confidence

ELNA date code (four digits, YYWW)1990s-2000s (documented 2000 and 2003 samples) · 2 rows · Medium confidence

Rubycon date code (plant letter + YYWW)1990s-2000s (documented 2002 and 2008 samples) · 3 rows · Medium confidence

Matsushita / Panasonic lot-code date (xYMD), SMD parts2020s SMD parts (documented example decoded as April 2023) · 1 rows · Low confidence

Nichicon month letters J-Z (official notice, power capacitors and reactors)2004 production numbers; the notice itself is dated 2022-04-01 · 4 rows · High confidence

Class A heat, bias and the dating trap - safety notes for this wavewhole Class A vintage period (1967-present) · 3 rows · High confidence

10 Revox (Willi Studer) models are catalogued with their production years, specs and safety notes.