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I'm stocking up on a variety of potentiometers to keep on hand for my audio projects, and I'm trying to figure out what to buy.

The projects I'm working on seen to call for either linear & audio taper pots. I know the difference between linear and log, but where does audio taper fit into the mix?

Here's what I've researched so far:

  • No schematic or parts list has BOTH linear and audio.
  • Looking at the Bourns pot spec sheets, they seem to be using linear and audio taper synonymously, but they have different part numbers.
  • Sites like mouser and digikey often have, say, a 10k linear and a 10k log, but no 10k audio pot in a search. However, when I search on the Bourns part number for an audio taper, the part is described by mouser as linear taper.
  • A lot of audio forums I've been trolling talk about pots as either audio or linear, but they don't appear to be synonymous in the discussions.

See why I'm confused?

So once and for all...can someone school me on the difference between linear and audio taper? I'm also interested to know how to decide which to choose for a particular application, and if they are different enough to have distinct uses, what types of interesting and unexpected results will I experience if I substitute one for the other?

dwwilson66
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4 Answers4

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Some rotary Pot's com in Linear, Audio and reverse Audio (where audio=log taper)

Actually it is "quasi"-log scale and not precision logarithm.

Notice it has a rapid transition from two different linear slopes. which gives you more sensitivity over a wider range of audio inputs rather than an apparent Off to ON effect if using a linear pot. If one adjusts audio equipment over a 30 dB range, that might occur in the 1st 5% of a Linear pot.

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Many options may be selected when you order. enter image description here

Precision Log pots would be mcuch more expensive than

Tony Stewart EE75
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Very simply, with a linear taper, if you turn the pot halfway, the resistance measured on each side will be equal. With logarithmic (aka "audio") taper, that is not true; the resistance follows a logarithmic progression.

Log taper is used because it gives a more natural progression when used for volume control.

Eric Gunnerson
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The difference between audio & taper is if you want to use a pot that is linear taper it is to provide an adjustment for a device or a feed to a device. An audio taper is a volume control or bass or treble control etc. In a fender amp the control that feeds the adjustment for the balance is linear taper since it adjusts the resistance between the screen grids. The idea that you could use two controls is a good idea and I would recommend this process. Just remember if you do any mods check your work carefully and test your voltages to make sure everything is ok

Beetle
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  • The normal Baxendall type of treble or bass control requires a linear taper pot. You are correct for volume controls. – Kevin White Jan 03 '17 at 03:27
  • The normal pre-Baxandall passive tone controls inside a gain stage also use linear pots. – user207421 Nov 29 '17 at 00:35
  • @KevinWhite I'm looking at a schematic for an Ampeg BT15 (50 W solid state) bass amp. This is an early 1970s model amp. The tone pots are 100k log tapers. – Bill N Dec 07 '17 at 19:54
  • @BillN - it depends upon how the tone circuitry is arranged. The classic Baxendall circuit with the pots in the negative feedback loop uses linear pots. Other arrangements that are not in the feedback loop may require log pots - I've seen it referred to as a "Jones tone stack". – Kevin White Dec 08 '17 at 21:23
  • @KevinWhite Thanks for the response. Based on https://www.ampbooks.com/mobile/amp-technology/james-tonestack-analysis/ the Ampeg is definitely a Jones tone stack. – Bill N Dec 09 '17 at 04:25
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"Audio Taper" is not strictly defined as it is determined by the particular manufacturer. It's basically a log taper but modified so as to give greater sensitivity around the '0dB' point. eg for a linear fader. For specific tapers I suggest contacting manufacturers who make pots specifically for audio applications eg P&G (Curtiss Wright), ALPS, TKD

Ilya
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Newmarket
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