Dating a guitar pedal

Hardly any pedal maker publishes a way to date one, and the serial number on the box is usually an inventory number. What is inside is a different matter. Open a pedal and the chips carry the week they were made, stamped on them at the factory, and so do the potentiometers.

It dates the part, not the pedal. A chip sat in a tray before it was soldered in, so its code is the earliest the pedal can be — never the day it was built. On a pedal the gap is usually small, and it is never zero.

Where to look, and what you will see

Every integrated circuit in a pedal is printed with a part number and a date code. It is almost always four digits: two of year, two of week. 7932 is the 32nd week of 1979.

The quickest way to tell a date code from everything else is that its last two digits cannot exceed 52. If they do, you are looking at something else — a part number, a batch code, a lot number.

Read every chip, not one. A pedal cannot be older than the newest part in it, so the latest code you find is the floor. One early chip proves nothing on its own; it may simply have sat in a drawer longer than the others.

The potentiometers say the same thing, in a different format

Pots carry an EIA source-date code instead: a three-digit maker number, then the date. 137 7932 is CTS, 1979, week 32.

That format is decoded on the amplifier page, and it is deliberately not duplicated here. Two copies of the same logic drift apart, and when they do there is no way to tell from either page which one is wrong.

One refinement from the people who date MXR pedals this way, which is worth having and is worth treating as a rule of thumb rather than arithmetic: add about three months to a pot date for the time between the pot being made and the pedal being assembled.

What the makers publish

Very little, and less than for guitars or amplifiers.

Looked at, and nothing usable was found

These have been researched and none of them publishes a way to date a pedal. They are grouped by why, because on this page the group is almost always more useful than the row.

Built by somebody else, or a badge on another firm's board

A pedal brand is not always a pedal factory. Where the board was made by another company, that company is the thing to look up — and it is usually the one with the date codes.

A modern shop, where a dating scheme has never been needed

Most of these are younger than twenty years, and several are younger than ten. A pedal that is not yet old enough to be vintage has no dating problem, which is why nobody has solved one. Nearly all of them will answer an email, and several write a build date inside by hand.

A digital box, where the question is usually the firmware

For these the useful question is rarely the year of manufacture. It is which hardware revision and which software version, and the makers publish that. None publishes a date scheme.

This list is thin, and that is worth saying first

The guitar page worked through 195 names and the amplifier page 93. Wikipedia's effects category yields 47 — and that is not because there are fewer pedal makers. It is because most of them are small, recent, and below the bar for having an article at all.

Checked rather than assumed. Seven of the best-known names in the field have no Wikipedia article:

Two more — Analog Man and Roger Mayer — have articles that sit in no effects-maker category, so a sweep of the categories misses them as well.

All forty-seven on it have been looked at — 6 have an entry above and 41 were researched and came back with nothing usable. But that is finishing a list, not answering a subject.

So this page cannot say what the guitar page says. There, working through the list was close to a complete answer. Here it is openly a partial one. That is stated at the top rather than in a footnote, because a list that looks complete and is not is worse than one that admits it — and because telling us who is missing is unusually useful on this page.

The tool above does not care about any of this. A chip date code works on a pedal from a maker nobody has ever heard of, which is most of them.