School me on pot variance/tolerances

[Artie]

Two more pieces of info:

A pot labeled A or Audio isn't necessarily a 10% pot
Lower quality 10% pots can easily fall between 7% and 20% at the center without being out of spec.

To make matters worse, in the old days, "A" was linear and "B" was log. Then they said . . . wouldn't it be better to have "A" stand for audio? And they flipped them.

https://sound-au.com/pots.htm

 

[GuitarStv]

No it's not only the batch. Logarithmic Pots come in different flavours, which are characterized by the point of 50% rotation. In your left curve you see a 10% log pot, in your right pic you see a 25%log pot (yellow) and 20% (red and blue). The difference between red and blue might be batch, manufacturer or material of the resistance board.

That makes sense. I don't usually see this spec listed when buying pots, but it would explain a lot of the variance. With the pic I was more just trying to point out that 'log' pots aren't logarithmic at all . . . they're made up of a couple different linear runs normally to approximate logarithmic operation.

 

[Aceman]

Wow - I have always "known" pot variance was a thing for why pedal A might be different than pedal B of the same type, but yowza!

That explains way more variation than I thought...

I suddenly question ANY vide that shows knobs at the same location to compare. Top end and bottom end make sense, but in-between, could be whatever (and so could the top and bottoms!)

 

[ErikH]

Based on all of this, which I've been aware of, when I'm buy potentiometers for a guitar or a pedal build (if it doesn't come with any), I aim to get +/- 10% variance. Those have been a good bet for me, whether it be CTS or Alpha.