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I was recently introduced to the term "pots" to mean "dials" or "knobs" in the field of sound design and audio engineering. (It rather took me by surprise; I had no idea what the sound designer was talking about, until it was explained to me.)

Later, I looked the term up, and found - well, not much. The dictionaries and thesauri available to me didn't contain this particular meaning of the word. I was able to find the term used in a few forum posts, but what I really wanted to know was how the term came to be used at all.

So, I ask: What is the origin of "pots" as a word meaning "dials?" Is it derived from the other meanings of the word? Is it a loanword from some other language? Was it coined from a long-forgotten acronym? I can't help but be curious.

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Boy, this one takes me back to the good old Synthi 100 days... –  BobRodes Mar 20 at 2:41

5 Answers 5

up vote 76 down vote accepted

Pot is short for "potentiometer". It's the doodad behind the panel, connected to the knob, that divides the voltage ("potential") between two ends of an element. It does not mean knob, nor does it mean dial. Loosely also used to refer to a rheostat, which is an adjustable resistance rather than two resistances that are used to divide voltage.

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Just to expand on that a little - that's how a volume control works and the same component is likely to be used in analogue hardware for tone and balance controls - i.e. most of the knobs on an analogue mixer. By extension the term is used for digital hardware, to the extent that the term digipot has come into use. –  Chris H Mar 18 at 9:16
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Since we're there, on some digital systems, rotary encoders are replacing traditional potentiometers. In systems using digital signal processing, it isn't useful to have an analog device directly modifying the signal. Instead, rotary encoders can be used to provide users potentiometer-like user interface to users who are expecting it an avoid the troubles of interfacing potentiometers with digital systems. –  AndrejaKo Mar 18 at 12:56
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@ChrisH Also trimpot (a pot intended for only occasional adjustment) and Helipot (trademark for a pot with a helical element). –  Spehro Pefhany Mar 18 at 13:23
    
@AndrejaKo... and rotary encoders are often referred to in the field as digipots, as they can appear the same to the user. –  Chris H Mar 18 at 13:26
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@ChrisH: As an electronics engineer, I haven't heard "digipot" used to refer to a rotary encoder, but rather to an electronics element which simulates a potentiometer whose position is set digitally. I wouldn't be surprised if sound engineers use the term differently, though. –  supercat Mar 18 at 16:57

"Pot" comes from "Potentiometer".

http://en.m.wikipedia.org/wiki/Potentiometer

These are under the knobs and are the active part.

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A potentiometer is a variable resistor, commonly implemented as a rotary mechanism. If you apply a fixed voltage to one side, the amount of resistance will vary as you turn it, changing the potential (voltage to ground) on the other side. Ergo, potentiometer. This being too long-winded for most people, it is informally shortened to pot. –  Phil Perry Mar 18 at 14:14
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The wiki article is a bit of a mess; it may be worth noting that the "-meter" aspect of a potentiometer is a consequence of the first major usage of the devices: one could measure an unknown voltage by determining the ratio of resistances that would balance a circuit containing the unknown voltage and a known one. Potentiometers that allowed the resistance ratio to be accurately measured predate the invention of any other form of accurate voltage measuring device. –  supercat Mar 18 at 17:03

To cut to the chase:

They call it a "pot" because what we normally think of as a dial or control has the technical name of "potentiometer".

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How is this answer any different from the other two? –  Mari-Lou A Mar 19 at 6:46

A potentiometer always has three electrical terminals and so forms a true adjustable potential divider (potential ≡ voltage). This passes a fraction of the signal (i.e. from 0 to 100% depending on how far the attached knob is turned or slid) on to the next stage of amplification in the audio mixer, radio, TV set, drill speed control, lamp dimmer or almost any other electronic device with a "knob" on it :)

This is as opposed to the more general term "rheostat" or variable resistor which usually only has two terminals.

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As interesting as this is, it doesn't explain why "pot" is used as a name for dials. –  Matt Эллен Mar 19 at 10:43

POT is short for potential divider and can be used to describe any process which attenuates the input signal. So if your dial reads too high, you adjust the pot to reduce it. Potentiometers for sound engineering are quite different from rheostats or other circuitry which you might find in a light dimmer because sound is logarithmic in volume, hence the potential divider has to be logarithmic as well. Potentiometers are available with a logarithmic characteristic but are only used on cheap systems, more expensive systems use a linear pot in conjunction with a logarithmic amplifier.

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