Audio or linear pots. What makes them different?

[smac4th]

I use both the tone and volume pots on my guitars alot but never really thought about it. What is the difference between audio and linear pots?

[Tom Phillips]

The taper of the resistance change vs. shaft rotation is different and there are more variations than the two (Liner & Audio taper).
Check out the article "The Secret Life of Pots" at The Secret Life of Pots
The various pot tapers and more are explained very well.

[smac4th]

Since I want a volume pot that can give a sweep effect as I raise and lower the volume I would want an audio taper pot, right?

[The Dude]

Yes. An audio taper pot will give you a more gradual volume change as you sweep the pot.

[Chuck H]

Yes. An audio taper pot will give you a more gradual volume change as you sweep the pot.

And to add... The specific audio taper can also be important. There's a wide range of tapers available ranging from 10%ish to about 30%ish at 50% pot rotation. IMHE the more gain you prefer the lower the number you'll want. Bournes makes a good 10% taper pot and I've been using them happily.

[eschertron]

And to add... The specific audio taper can also be important. There's a wide range of tapers available ranging from 10%ish to about 30%ish at 50% pot rotation. IMHE the more gain you prefer the lower the number you'll want. Bournes makes a good 10% taper pot and I've been using them happily.

The audio/log pots that I've tested (Alpha, CTS, PEC, and Bournes) all seem to be 10% taper. I'd like to get a hold of some 30% taper pots, but haven't seen them specifically advertised. Do you have a line on some different tapers?

[Mark Hammer]

All of this essentially boils down to the way your senses work. For all senses, small differences in intensity are detectable at the low end, but as the stimulus gets more intense - whether visual, auditory, taste, or whatever - it takes bigger and bigger changes to make a "jnd" (just noticeable difference). So the taper on audio pots is intended to produce small changes with rotation at the low end, and bigger changes at the high end, for roughly the same number of degrees of rotation.

Linear-taper pots are useful when the "middle" of something is desirable to know. For example, many cut/boost or mix/balance controls use linear pots since the middle position of that pot will have equal resistances on each "side" of the midpoint.

[potatofarmer]

The audio/log pots that I've tested (Alpha, CTS, PEC, and Bournes) all seem to be 10% taper. I'd like to get a hold of some 30% taper pots, but haven't seen them specifically advertised. Do you have a line on some different tapers?

Ugh, why?? My Twin is full of CTS J taper (30%) pots and I find them unbearable; they come up way too fast. It looks like you can still specify them from CTS (at least in the 450G series) but if you want fewer than a few hundred I'm not sure where to get them. I'd pull mine and sell them but the cost (and time) doing so greatly outweighs the extra 15 seconds I need to spend lightly brushing the bass pot to between "2.5" and "2.6" without reaching "2.7" where the bass jumps up drastically.

edit: Here's a link: Fender 1 Meg Solid Shaft J Panel Mount Pot For Amplifiers

My two cents: I've found that for pots where you're increasing from zero (an amp's volume control for example) that audio taper provides the smoothest transition from quiet to loud. Conversely when you're decreasing from 100% (guitar's volume control or volume pedal) linear provides a smoother transition from loud to quiet.

Gibson typically uses linear taper volume pots and audio taper tone pots, which I've found more useful than Fender's use of audio taper volume pots and linear taper tone pots. In the guitar though it's personal preference of the user. Where do you want most of the sweep to be? With an audio taper volume pot, to me it feels like nothing happens between 10-7 and then there's a sudden drop between 5-0, while with a linear taper volume pot there's a fast drop from 10-5, but a slow drop below that.

I actually have a reverse audio taper in my volume pedal which I've found ideal for swells.

[Chuck H]

Ok... I knew something was up when eschertron posted that Alpha's audio pots are all 10% taper so I went to my stash and took some measurements. My memory was that the standard Alpha pots were as follows:

1MA =10%
500kA=15%
250kA=25%

I only had some 1MA and two 500kA pots to test (no 250kA in stock). One of the 500kA pots is old stock and one more recently purchased. The 1MA measured 10%, as expected. The old 500kA pot measured 15% and the new one measured 10%. Aha! Indeed Alpha must have changed their MO because when eschertron asked about a source for 30% pots I almost suggested that the Alpha 250kA pot wasn't a 10%, but rather a 25%. Glad I checked. I expect if I had a new Alpha 250kA to measure it would probably be 10%. I'd have to open one of my amps to measure an old 250kA. Not going there. But trust me. They use to be 25%.

[eschertron]

why??

Fooling with Duncan's Tone Stack Calculator - Download for those playing along at home - I've seen some circuits that are kind of a cross between a tilt control (using a linear pot) and a filter (using an audio taper pot). I wanted to build using a 30% taper so I can evaluate for myself any perceptual differences, and form my opinion

edit: Here's a link: Fender 1 Meg Solid Shaft J Panel Mount Pot For Amplifiers

Thanks for the link. I'll try it, even though $9 is serious investment!

My two cents: I've found that for pots where you're increasing from zero (an amp's volume control for example) that audio taper provides the smoothest transition from quiet to loud. Conversely when you're decreasing from 100% (guitar's volume control or volume pedal) linear provides a smoother transition from loud to quiet.

Good description, and very on-topic for the OP. I have found that on my guitar, if I'm feeding a high-gain amp, that even the audio taper has an excessive jump at the bottom of the range. So I might try a linear pot in that position for better control near the top, since I'm not using the other half of the pot for much!

[eschertron]

Ok... I knew something was up when eschertron posted that Alpha's audio pots are all 10% taper...

Well, actually I posted that they seem to be 10%. My testing routine generally involves trying to get the wiper to the halfway point, often with no knob or indicator to use as reference. So a 15% taper is certainly within my testing margin of error! I will have to go back now and be a bit more rigorous. If have some 25% pots, I'll mark them as such for my tinkering

[Chuck H]

Well, actually I posted that they seem to be 10%. My testing routine generally involves trying to get the wiper to the halfway point, often with no knob or indicator to use as reference. So a 15% taper is certainly within my testing margin of error! I will have to go back now and be a bit more rigorous. If have some 25% pots, I'll mark them as such for my tinkering

My testing method was much more scientific and rigorous. I drew a line on the shaft end with a pencil