Today I’m going to complain about audio potentiometer taper naming.

So, a long time ago, in a land far away, I was a young (devilishly handsome) British engineer – I even thought I was European – but heh, and I started to learn me some things…
Like a linear pot was marked A – eg A100k, and logarithmic pots were marked B – eg B100k. I was also vaguely familiar with other tapers as well, like anti-log, but never used those in non-audio embedded designs.

So what does A100k mean in the US? Yes, you’re right LOGARITHMIC!!! How on earth!? Why!?

It gets worse – here’s a list of the naming standards around the world…

UK/EU
Linear A
Log B
Anti-log F

US
Linear B
Log A
Anti-log C

Asia
Linear B
Log A
Anti-log ?

Vishay
Linear A
Log L
Anti-log F

Also, I’ve been doing a bit of research on modifying tapers – the idea of using a linear pot and adding one or two resistors in ‘parallel’ between the wiper and each end, to create an approximation of a log or anti-log taper. I’m keen on this as it potentially helps reduce parts / inventory for different builds. I need to find a good model / tool to make this a fast design stage… More soon.

Useful taper graphs – image courtesy Keiko Corp