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Different kinds of potentiometers

Started by m-Kresol, December 17, 2013, 11:42:46 PM

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m-Kresol

Ok, there's a noob question for you: There are three kinds of potis (linear, logarithmic and reverse logarithmic), but there's also an old and a new way to mark them. I know that B is linear, but I'm never quite sure about A and C. A was the labeling for "audio" which was/is used as volume regulators and are usually logarithmic. Therefore I thought that C has to be reverse logarithmic, but apparently C was also used for logarithmic at some point.
As I'm going to order some parts for my function-f(x) projects, I just want to make sure to order the right ones.
There are 2 A100k volume potis in the nomojo fuzz, which should be logarithmic.
In the duovibe, there's a C100k for the Rate poti (btw. if any of the function f(x) founders read this thread, there's a mistake in the BOM of the Duovibe. One of the pots is missing in the BOM and it says the wrong value for the depth pot, if the schematic is correct.) There's also a C-Poti in the zeropoint SDX i just finished up and if I remember right, it said C on the enclosure, but it was a standard logarithmic pot, so now I'm rather confused if I should get logarithmic or reverse log.
If anyone could enlighten me please? Is there a standard marking used in this DIY community? Thanks!
I build pedals to hide my lousy playing.

My projects are labeled Quantum Effects. My shared OSH park projects: https://oshpark.com/profiles/m-Kresol
My build docs and tutorials

croquet hoop

#1
The standard is pretty much what you assume.

A = log (audio, the way the ear perceivessound, think of the dB curve)
B = linear (it's easy to remember if you've heard of Linear B)
C = reverse log
There is also W, used mainly for the tube screamer tone pot

It is not uncommon for builders to use one type in place of another, depending on what they have on hand; typically the "right" taper is the one that makes the whole rotation of the pot useful, but using the "wrong" type will not make your effect unusable (maybe a bit harder to dial in).

m-Kresol

Thanks! I guess I used the wrong one in my delay then. But it works great anyhow.
I build pedals to hide my lousy playing.

My projects are labeled Quantum Effects. My shared OSH park projects: https://oshpark.com/profiles/m-Kresol
My build docs and tutorials