Potentiometers Demystified
Photos and Captions Contributed by BrianGWN

From left to right these pots are a recent Gibson regular length shaft pot typical of what has been in the recent Historic Les Pauls, a recent Gibson long length shaft pot typical of what has been in the recent regular production Les Pauls, a CTS made AllParts regular length shaft pot AllParts number EP086, a CTS made AllParts long length shaft pot AllParts number EP686, and CTS made for Gibson long shaft pot from the mid 1990s.

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From left to right, recent Gibson short shaft, AllParts CTS short shaft, recent Gibson long shaft, AllParts CTS long shaft, CTS made for Gibson long shaft. Note some of the differences, the AllParts CTS short shaft has a top portion that is some kind of cast metal instead of a piece of stamped steel. The AllParts CTS pots have what appears to be an aluminum shaft, as opposed to the brass shaft of the older CTS made for Gibson. I inquired to AllParts about the shafts, they couldn't tell me much. It could be a cost reduction or maybe for saving weight. Note that the CTS short shaft and CTS made for Gibson pots have the four metal tabs bent up to allow the pot to be disassembled. Note that when comparing the AllParts and recent Gibson short shafts, the AllPart CTS pot has a small extra portion at the end beyond the knurling. Someone noticed that if replacing just the two volume pots in an Historic LesPaul, the knobs ended up sitting up just a bit higher than the original Gibsons due to this little extra at the end of the shaft. I recently installed two such pots in a friend's Historic, but I prepared them ahead of time by taking them to a bench power grinder and removed that extra 1/16 or so grinding the end of the shaft level with the knurling.

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This is a recent Gibson long shaft pot with the body / cover removed, out of a 1998 LP Classic. Note the plastic internals. These pots just do not hold up to repeat soldering. Do you see any problem???

Did you spot the problem? The substrate material of the pot managed to _crack_ all the way through including through the carbon resistive track of the pot.

This is another pic of the Gibson pot with a crack.

This is a Gibson pot alongside a CTS pot. Compare the fragile wiper body and resistive substrate made of plastic versus the CTS heat tolerate heavier more rugged design and materials.

This pic of the disassembled pots focuses on the miniature wiper of the Gibson pot versus the heavy brass wiper of the CTS pot.

This shows the pots further disassembled, Gibson to the left, CTS to the right. Note the much _much_ larger brass wiper and the heavier design and construction of the resistive element of the CTS, versus the little wiper of the Gibson with the five tiny fingers.

Another angle showing the disassembled pots.

Sobering sight... A side view of a CTS pot versus the Gibson. Note the heavy brass wiper, thicker resistive element, heat tolerate materials in the CTS versus the rather wimpy little wiper, plastic guts, and minimal resistive element in the Gibson.

Another pic of the side view comparison, CTS pot versus recent Gibson.

Here's another pic of the cracked Gibson pot, this time with a little commentary added courtesy of Mayor Dave.

This pic illustrates the "nail polish mod". By applying some insulation such as clear nail polish in this area of the resistive element track, you create a tone pot that disconnects as you turn it to full on, as you adjust from 9 to 10. Disconnecting the tone pot can help to bring out some extra response and clarity with the higher output pickups such as the Gibson 498T or 500T, Seymour Duncan models Duncan Custom, Duncan Distortion, or similar.

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