You’ve found some pots in the back of your parts drawer and they look like CTS pots but you have no idea what value or taper they are. No problem! Today we are going to examine the numbers stamped on the bottom of CTS pots and decode them so that you too can figure out what pots you have.
First, let’s take a look at the bottom of two different CTS pots:
The pot on the left has the following inscription: 450GT36K254B1S 1641 CTS. The pot on the right has the following inscription: 450GT69K504B2S 1405 CTS. Now, let’s break down these codes:
As we can see from the above diagram, 450G is the CTS model number of the pot (made specifically for guitars). So let’s get started with the first pot.
450G T 3 6 K 254 B 1 S 1641 CTS
The chart above tells us it’s a 450G series, solder lug, 3/8″ bushing length, 3/4″ shaft length, split/knurled shaft, 250k resistance, 20% tolerance, linear taper, standard torque (rotating resistance). The second set of numbers is the date code. In this case, 1641 = 2016, 41st week. Newer pots are now stamped with CTS, but older pots will be stamped with 137, which is the code designated for CTS pots.
Let’s check the second pot.
450G T 6 9 K 504 B 2 S 1405 CTS
We have a 450G series, solder lug, 3/4″ bushing length, 1 1/4″ shaft length, split/knurled shaft, 500k resistance, 20% tolerance, audio taper, standard torque. Manufactured the 5th week of 2014.
One big exception to this code structure are OEM pots made by CTS for other companies. Many pots in circulation are stamped with an EP code, like EP086, instead of the 450G code. These are manufactured for Allparts. Gibson also has their own code sequence and I’m sure there are others as well. In those cases, you may need to reach out to the vendor to get a breakdown of their codes.