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Vintage Guitar Pot Codes: How to Date Your Guitar by Its Potentiometers
Vintage Guitar Pot Codes: How to Date Your Guitar by Its Potentiometers
Last Updated: June 2026
The potentiometers behind a vintage guitar’s volume and tone knobs are one of the most reliable, hardest-to-fake clues to when the instrument was actually built. Most American pots carry a stamped source-date code that names the company that made the pot and the exact week and year it left the factory. Read correctly, that code sets a firm “this guitar can be no older than” floor that serial numbers alone don’t always give you. Here is how to find, read, and sanity-check those codes, and the traps that fool even seasoned buyers.
What Is a Pot Code?
American potentiometer makers stamped each pot with a six- or seven-digit EIA source-date code. EIA stands for the Electronic Industries Alliance, which assigned every U.S. parts manufacturer a unique three-digit source code. The remaining digits encode the production date. So a single number tells you two things at once: who made the pot, and when.
You will find the code stamped into the metal casing, either around the side of the cylindrical can or on the flat back. On a Fender you usually read it through the control-plate or pickguard opening; on a Gibson you read it through the rear control cavity. A flashlight, and on hollow-body archtops a small dental mirror, make all the difference.
How to Read a Pot Code, Step by Step
Take a typical seven-digit code like 137 7421 and break it into two parts.
The first three digits are the EIA manufacturer code. 137 is CTS, the most common supplier to both Fender and Gibson.
On a seven-digit code the next two digits are the year and the final two are the week. 74 21 means 1974, the 21st week.
On a shorter 1960s code there is often a single year digit followed by a two-digit week, which is more ambiguous and needs cross-checking.
So 137 7421 decodes to CTS, made the 21st week of 1974. The guitar it sits in was assembled that week or later.
Common EIA Manufacturer Codes
EIA Code | Manufacturer | Where you’ll see it |
|---|---|---|
137 | CTS | The most common pot on vintage Fender and Gibson |
134 | Centralab | Frequent on 1950s and 1960s Gibson |
304 | Stackpole | Often found on Fender |
106 | Allen-Bradley | Seen on some Gibson |
140 | Clarostat | Less common |
381 | Bourns | Later-era production |
Decoding the Date Digits
The year is the part people get wrong. Seven-digit codes spell out a two-digit year and are unambiguous within a century. Shorter 1960s codes can use a single year digit, so the same stamp could read as 1966 or 1956. You resolve it with the guitar’s other features and the simple fact that a pot cannot predate the code format it carries. Pots made late in a year sometimes ended up in instruments built early the next year, so treat the week as approximate.
Sanity-check the week number: it should fall between 01 and 52. A “week” above 52 means you have split the year and week digits in the wrong place. Re-read the code.
The Most Important Caveat: Pots Date the Pot, Not the Guitar
A pot code tells you when the potentiometer was made, not when the guitar was. Two honest realities follow. First, factories bought pots in batches and installed them weeks or months later, so a guitar is usually a touch newer than its pots, occasionally by close to a year. Second, pots are consumable parts that scratch, fail, and get replaced. A 1962 Stratocaster with a single 1965 pot almost certainly had a repair, not a trip through time.
Use pot codes as corroboration, never as sole proof. The dependable rule is the floor: a guitar cannot be older than its oldest original-looking pot. When the pots, the neck date, and the serial number all agree within a year or so, you have a strong, consistent story. When one pot is wildly out of step, you have a question worth answering before you buy.
Fender Versus Gibson Specifics
On Fenders, the neck date stamped on the heel is the primary reference and pot codes back it up; both are easy to read with the neck off or through the control plate. On Gibsons, which rarely carry a neck date, pot codes carry more weight as an independent check alongside the serial number and the factory order number. Either way, look at every pot. A matched set from one maker and the same quarter is exactly what you want to see.
Red Flags and Replaced Pots
One pot dramatically newer than the others, which usually points to a repair; check that the solder joints look period-correct.
A full set of new pots on a guitar sold as all-original, which is a serious value hit because originality is the whole premium.
Codes that will not decode cleanly, such as impossible week numbers or unknown EIA codes; re-read carefully, then suspect a non-original part.
Solder that looks bright, fresh, or blobby around the pot lugs on an otherwise aged wiring harness.
Frequently Asked Questions
Can a pot code prove the exact year my guitar was made?
No. It proves when the pot was made, which sets the earliest possible date for the guitar. Combine it with the serial number, neck date, and features to land on an actual build year.
What if my pots have different dates?
A spread of a few weeks, or even a couple of quarters within the same period, is normal and reassuring. A single far-off outlier usually means that one pot was replaced.
My guitar has no readable codes. Is that bad?
Not necessarily. Some imported and budget pots were never coded, and decades of grime can hide a stamp. Clean gently and use a light; if they are genuinely uncoded, lean on the serial number, neck date, and hardware instead.
Confirm the Year, Then Find Out What It’s Worth
Once the pots point you to a period, confirm the year with our Fender Serial Number Lookup and Gibson Serial Number Lookup tools. And when you are ready to sell, Edgewater Guitars pays vintage owners 30 to 40 percent more than a typical shop offer.
