We’re not talking about dinner and a movie, of course…

For my first blog post on dating instruments, I’d thought I’d talk about potentiometer or, “Pot” codes which can be used to help date almost all electric instruments, amplifiers, and effects pedals made in the U. The Pots are the small parts responsible for the volume and tone controls.

Also some sockets are used, but sockets DO NOT FIT in an MXR pedal due to construction, so good luck getting the bottom plate on.

- All vintage USA Big Muffs have source-date codes stamped on the underside of the potentiometer cans, or “pots”.

The pots are what the knobs are mounted to, essentally manually adjustable resisitors that control the voltage across a circuit.

They now make polyester film capacitors) 106 – Allen-Bradley Corp.

(Make potentiometers and from El Paso, Texas) 117- Credence Speakers, Inc (Kevil, Kentucky) 124- Alpha Wire Corp. You can find old spools of wire and see codes and dates on the reels) 134- Mepco/Centra Lab, Inc. Philips Corp.) 137- CTS Corporation (made amplifier and instrument potentiometers and are based in Elkhart, Indiana) 140- Clarostat Mfg. (made pots for early Fenders and had code stamped in blue ink) 145- Illinoise Capacitor, Inc.

Then two more numeral digits are added for the year such as 63 and another two are added for the week of production. Again the 134 represents Centra Lab for the potentiometer manufacturer, the 63 stands for the year 1963 and the 20 represents the 20th week of production.

If a component manufacturer is unable to use the four (4) digit code date, an alternate three-digit (3) code may be used by taking only the last digit of the year.

So a pot stamped 1377833 is a CTS pot made in the 33rd week of 1978.

Note that this does not mean a Muff with a 1978 pot was actually made in 1978, it just means it was not made much earlier than 1978.

This can be done by adding, following a hyphen (-), the last two digits of the production year plus the number of the week of that year.