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Thread: Tone Pots: Linear or Audio? Why?

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    Member SlidePicker's Avatar
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    Smile Tone Pots: Linear or Audio? Why?

    I've seen recommendations for both linear and audio taper guitar tone pots. Which works best? Why?

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    The general rule of thumb is that audio taper is used for volume and anything approximating the volume-like function, where linear is used whenever knowing the "middle" of something is important. As you might expect, linear pots are used for things like blend/mix/balance controls, as well as for EQ controls where identifying exactly where you are either boosting or cutting is important.

    Beyond that, my experience is that it would depend on your needs. Some folks want all the control at one end of the range, some want it at the other, where others want equivalent "dialability" over the entire range of control for that pot. For instance, say an LFO for a flanger goes from .1hz (one sweep every 10 seconds) to 5hz (5 sweeps per second). One player may want to be able to dial in subtle differences between .1 and .5hz, where another may be far more interested in the range between .7 and 3hz. What makes for more "dialability" for the one player may be exasperatingly restrictive for the other. And THAT is the essence of pot taper; you go with the taper that allows you to easily replicate settings you are interested in. In some instances, that might be linear, in others audio/log, and in others it may be reverse audio/log.

    My own inclinations lately have been to use a bidirectional tone pot, where I treat a single 1meg linear pot as two parallel tone controls, each with a different kind of rolloff. In one direction it cuts at one frequency, in the other it cuts at a different frequency, and in the middle it doesn't cut at all. Because I have essentially taken the rotation of each virtual control and cut the amout of rotation needed in half, it really doesn't matter what the taper is because with such a reduced range of rotation, you don't have the sense of portions of the rotation as being "useless" - i.e., you notice an effect no matter which way you turn or how much.

    For folks who like a traditional sort of tone control, though, you can wire up either a lin or log pot and it'll work just fine. If you want to be able to dial in small differences in mutedness, you may want to go with log or reverse log. If you feel more at ease knowing that you really need to roll back the tone control before you start losing treble, then linear is likely better.

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    Member SlidePicker's Avatar
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    Thanks, Mark!

    How about in the typical situation with a pot and tone capacitor in series, shunting the output of a pickup?

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    Well again, I have to ask you: What do you normally use your tone control for and how often? I also have to ask if this is a LP-type dual vol/tone scenario, a Tele-type single vol/tone scenario, or a Strat-type vol/tone/tone scenario.

    Some info about your normal needs will shed appropriate light on what strategy to deploy.

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    Smile

    Personally, I mostly use the LP type arrangement. A volume and a tone pot for each pickup.

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    Okay, then the suggestion would be log. Why? Because those guitars/pickups tend not to have a whole heap of treble. As such, dialing in nuances of crispness is not really the primary function of the tone controls. My sense is that players of those types of guitars want a kind of "safe zone" whereby a tone pot set anywhere between maybe 7 and 10 won't really sound different. As if it was a zone you could haphazardly jump to to get away from muteness quickly, without having to worry about exactly where you set it, as long as it wasn't near 1-3. My apologies if I assume to much here.

    In any event, a 500k log pot will make most of the action happen in the 1-3 zone. A linear might as well, but a log pot definitely.

    Take a look at the "Secret Life of Pots" article over at www.geofex.com to learn more about custom-tapering pots. Since the classic tone control is essentially a variable resistor, this opens up lots of possibilities for using parallel fixed resistors in tandem with a 500k or even 1meg tone pot to achieve a taper that suits your own preferences.

    If it were my guitar, I'd use a tone cap of .01-.015uf for the bridge PU, and something a little higher (.022-.033uf) for the neck PU. Alternatively take a look at the nifty tone control used in the old Peavey T-60 guitar (http://www.peaveyt60.com/images/T-60%20wiring.jpg). It provided for a pan from single coil tap to humbucker to muted humbucker. A *very* clever circuit and guitar (http://www.peaveyt60.com/). Using a classic tone control for the bridge PU and the Peavey one for the neck PU would permit a huge spectrum of tonal possibilities without having to do ANY routing of the body whatsoever.

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    Smile

    Thanks, Mark!

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    And coming from my simpleton's POV, an audio pot will have a more even correlation between turning control and the ammount of increase or decrease of the desired tone: a smoother sweep, whereas a linear pot will kind of seem like it's doing nothing until you have turned it about half way. Then all of the tone sweep will be condensed into the second half of the turn. Personally, I don't like linear pots for that reason. I much prefer the even increase/decrease of audio taper pots.

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    Pickup Maker David Schwab's Avatar
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    I prefer linear pots for everything. I know how the ear works, but I like the fact that turned halfway up is half the volume or tone. The taper mostly comes into play as you are turning... if sounds smoother. But since I leave my volume and tone all the way up most of the time it doesn't matter.

    Likewise when I am adjusting volume or tone, I'm doing so with my ear, and I know when to stop turning.

    Generally though, audio (log) taper is used for volume, and linear taper is used for tone.

    While I'm on the subject... Stew-Mac sells a log taper dual ganged blend pot. Sounds like a good idea, except it should be one pot log, and the other anti log, but it isn't. They both go the same way, and make mixing pickups the ay you expect impossible! It's really a log taper stereo volume pot.
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    What David said, is what I always felt was right.
    Quote Originally Posted by David Schwab View Post
    "Generally though, audio (log) taper is used for volume, and linear taper is used for tone."
    The ear hears volume in a logarithmic fashion, so you would use a log pot for volume.
    I still could not understand why anybody would use anything but a linear pot for tone. The logarithmic compression that your ear hears in, is only for volume, not tone/frequency differentiation. The frequency response of your is not flat, but it isn't logarithmic. Your ear is most sensative from 1kHz to 4kHz. below 1kHz it starts to drop. It's a slope, but I still would consider this drop as linear
    Last edited by tboy; 02-12-2009 at 12:57 AM. Reason: quote fix

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    Quote Originally Posted by David Schwab View Post
    Generally though, audio (log) taper is used for volume, and linear taper is used for tone.
    That's what I had thought proper, and I've built amps that way.

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    Great comments guys. Thanks for the information!

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    Pickup Maker David Schwab's Avatar
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    Quote Originally Posted by zorro View Post
    What David said, is what I always felt was right.
    Quote Originally Posted by David Schwab View Post
    "Generally though, audio (log) taper is used for volume, and linear taper is used for tone."
    The ear hears volume in a logarithmic fashion, so you would use a log pot for volume.
    I still could not understand why anybody would use anything but a linear pot for tone. The logarithmic compression that your ear hears in, is only for volume, not tone/frequency differentiation. The frequency response of your is not flat, but it isn't logarithmic. Your ear is most sensative from 1kHz to 4kHz. below 1kHz it starts to drop. It's a slope, but I still would consider this drop as linear
    Yeah, you wouldn't use a log pot for a tone controls on an amp or console, so I have no idea why someone would want to use them for passive tone controls, unless they don't use their tone pot much.

    I also don't care for the tapers of some audio taper pots. Since they are not true log taper, but are a mix of two linear tapers, you get a sudden jump on the last 10% of the rotation. In cases like that, I'd rather have a linear taper pot for volume. Better quality audio taper pots work fine though.

    Unless you plan on doing fades, it doesn't matter, since you are setting the volume pot where you want it, and not listening to it as you sweep it.
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    Smile

    I appreciate your input. I've used the linear pots for treble-bleed tone pots on amps and guitars and found them to work just fine. I had an "expert" harshly berate me on a guitar board for my ignorance about that, but I know what my ears tell me works. I know it can't be regarded strictly as an isolated circuit element without effect from the inductance and capacitance of the surrounding circuit parts like pickups and cables, but the response of an RC filter with variable resistance ought to be linear.

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    Member jack briggs's Avatar
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    For guitars audio log taper for both volume and tone. Tried linear - didn't care for the tapers.



    Cheers,

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    What about for a mixer circuit that blends two preamps? Obviously a ganged linear would be correct since the pots would meet in the middle at 50% rotation, but I'm not sure how the ear would perceive that. Thoughts?

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    Pickup Maker David Schwab's Avatar
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    Dual ganged blend pots with center detents commonly used on basses to blend pickups often use M/N taper pots. It's kind of a log/anti log taper, but it's a bit more concentrated around the detent. EMG uses linear taper for their blend pots, and they work fine as well.

    Also for passive instruments, the taper can help with the loading you get when you turn the volume down. It's less noticeable with active instruments, which have a more even drop when you turn the volume down.

    Stereo balance controls are linear taper. Audio taper is needed when you are going to be changing the volume, like a fader on a mixer, and you want it to be smooth from quiet to loud.. or at least seem smooth.
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    I still maintain that optimal taper for a tone pot will depend on how you intend to use it.

    If, for example, you like to do pinky wah, then a log taper will let you cover a lot of ground quickly. If you use other cap values that would make it helpful to be able to cover a lot of ground quickly, simply because of the way in which you adjust tone, then log can be useful.

    Myself, I've taken to using a bidirectional tone pot in which I have a different tone cap at each extreme of the control's rotation, to produce two different rolloffs, and the mid-point is no rolloff. Obviously, in such an instance, the pot must be linear or else how would I ever know where the no-cut position is?

    If a person simply doesn't HAVE any particular agenda for their tone control, and is using stadard cap values, then linear is tried and true.

    Incidentally, there ARE other tapers besides lin and log, and you can create your own need-specific taper by means of paralleled resistors. Read this and find out how: http://www.geofex.com/Article_Folder...s/potscret.htm

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    Quote Originally Posted by David Schwab View Post
    Stereo balance controls are linear taper. Audio taper is needed when you are going to be changing the volume, like a fader on a mixer, and you want it to be smooth from quiet to loud.. or at least seem smooth.
    So for a situation like blending two preamps into one signal, it would be best to use a Linear pot?

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    I prefer Audio Taper for both Volume and Tone on Guitar. But the quality of the taper is very important. I had a nice Fender Nocaster , but was never happy with the feel of the Controls. I tried many different makes of pots, it was not until I bit the bullet and put in the Allesandro pots That it finally felt right.

    I also build amplifiers and most amp designs use Audio Taper for both Volume and Tone . The exception being the Middle control. I suspect it has something to do with The Fletcher Munson curves, Where the bass and treble frequencies are most skewed and the Middle frequencies are less affected by volume shifts.

    I find a good 10% audio taper to be about right, where the pot is at 50% rotation the first half is gaining 10 % value.

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    Pickup Maker David Schwab's Avatar
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    Quote Originally Posted by MarshallPlexi View Post
    So for a situation like blending two preamps into one signal, it would be best to use a Linear pot?
    Yes, because you want half way to be half way.
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    Sweet! I'll see how that works.

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    Quote Originally Posted by zorro View Post
    What David said, is what I always felt was right.


    The ear hears volume in a logarithmic fashion, so you would use a log pot for volume.
    I still could not understand why anybody would use anything but a linear pot for tone. The logarithmic compression that your ear hears in, is only for volume, not tone/frequency differentiation. The frequency response of your is not flat, but it isn't logarithmic. Your ear is most sensative from 1kHz to 4kHz. below 1kHz it starts to drop. It's a slope, but I still would consider this drop as linear
    the ear doesnt hear frequency in a log fashion, but the tone pot is actually a volume pot that effects the higher frequencies. it doesnt pan between frequencies, it just cuts a certain band an amount determined by the pot. if you want a smooth travel like a log pot used for volume, use a log pot. both types of pots have all the same values on them, so its not a big deal.

  24. #24
    Pickup Maker David Schwab's Avatar
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    I want to add that there is no right and wrong, just what you prefer. Either taper will function correctly, but you might like the feel better with one or the other. So it can't hurt to try one, and if you don't like the way works, try the other taper.
    It would be possible to describe everything scientifically, but it would make no sense; it would be without meaning, as if you described a Beethoven symphony as a variation of wave pressure. — Albert Einstein

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    Quote Originally Posted by jack briggs View Post
    For guitars audio log taper for both volume and tone. Tried linear - didn't care for the tapers.



    Cheers,
    I couldn't agree more. In fact I replace those stock 300k linear pots in Gibsons all the time because people complain about the taper. I put a 500k audio in place of it and they are always happy. Linear taper looks good on paper but sounds bad to the human ear. The linear taper isn't manageable at all in passive guitar circuits IMO.

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    Supporting Member tubeswell's Avatar
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    For my tuppence worth (since this thread has been resurrected), I understand that audio vs linear tapers work differently in different tone stack applications.

    Take a 5E3 tone control for example, the 1M Tone pot is in between a 500pF cap and a 5nF cap, and as the wiper goes down to the 5nF end, more frequencies altogether are passed to ground (making it more bassy) and as it goes to the 500pF end, more high frequencies are bypassed to the next stage (making it more trebly). So in that application the pot is more like a mixer/balance pot and a linear taper would work fine (but so does an audio taper).

    But where you have a simpler tone control, like a pot wired as variable resistor in parallel with smallish cap, it may be better for the pot to be audio taper to 'hear' the difference between hi and lo more evenly.
    Building a better world (one tube amp at a time)

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    Old Timer tedmich's Avatar
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    I agree with David as well, but mainly because its MUCH easier to find very high quality linear pots for cheap, like these:



    which are beautiful 2 watt cermet dual 5Meg pots made by Bourns which can be made into any lower value with a parallel resistor and separated into a trim pot and single pot quite easily...or used as a 10Meg guitar volume pot....

    AND cost $2 at www.goldmine-elec-products.com
    (no affiliation, I just bought all I needed)

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    Pickup Maker David Schwab's Avatar
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    Quote Originally Posted by tedmich View Post
    AND cost $2 at www.goldmine-elec-products.com
    (no affiliation, I just bought all I needed)
    Hey, cool! Thanks for the link!
    It would be possible to describe everything scientifically, but it would make no sense; it would be without meaning, as if you described a Beethoven symphony as a variation of wave pressure. — Albert Einstein

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    Supporting Member Steve A.'s Avatar
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    My two cents worth on this discussion...

    I have been replacing the audio volume pots on most of my guitars with linear pots for a specific reason: if you need to turn down your volume when it is set to 10 you have much more control with a linear pot. This is very important to me if I am constantly adjusting the on-board guitar volume control all night, from song to song and during the songs themselves. I was using my Tele B-Bender last weekend and I hadn't already replaced the audio taper volume control- it was a real b*tch keeping the volume at the levels I wanted.

    So my rule of thumb is this: if you are mainly concerned with turning down the volume from 10, then a linear taper works better. If you are mainly concerned with turning the volume up from 0- like doing swells- then an audio taper is better. (As is the case for all thumb rules, there are plenty of exceptions!)

    Of course someone might just use a volume pedal and leave their on-board volume pot(s) set to 10 but that ain't me...

    Steve Ahola

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    Old Timer tedmich's Avatar
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    Quote Originally Posted by SlidePicker View Post
    I've seen recommendations for both linear and audio taper guitar tone pots. Which works best? Why?
    someone has probably mentioned this, but when using a linear pot as a variable resistor (wiper tied to one leg) you can add a parallel resistor and make a pretty good approximation of a log/audio taper. You can't do this for a pot used as a voltage divider, google "secret life of pots" or see Rod Elliott's site

  31. #31
    Pickup Maker David Schwab's Avatar
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    Quote Originally Posted by Steve A. View Post
    My two cents worth on this discussion...

    I have been replacing the audio volume pots on most of my guitars with linear pots for a specific reason: if you need to turn down your volume when it is set to 10 you have much more control with a linear pot. This is very important to me if I am constantly adjusting the on-board guitar volume control all night, from song to song and during the songs themselves. I was using my Tele B-Bender last weekend and I hadn't already replaced the audio taper volume control- it was a real b*tch keeping the volume at the levels I wanted.

    So my rule of thumb is this: if you are mainly concerned with turning down the volume from 10, then a linear taper works better. If you are mainly concerned with turning the volume up from 0- like doing swells- then an audio taper is better. (As is the case for all thumb rules, there are plenty of exceptions!)

    Of course someone might just use a volume pedal and leave their on-board volume pot(s) set to 10 but that ain't me...

    Steve Ahola
    +1

    This is exactly what I have always been saying! Audio taper is to hear a smooth taper when doing fades. If you aren't turning the pot, it makes no difference.

    If you look at the faders on a mixer, you can see the log scale printed on the board. Faders are made to do fades, so they need that taper.

    If you want to know that you have reduced your output by half, when the pot is on 5, then you need a linear taper pot.
    It would be possible to describe everything scientifically, but it would make no sense; it would be without meaning, as if you described a Beethoven symphony as a variation of wave pressure. — Albert Einstein

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    That's a VERY interesting perspective, and one I'm ashamed to say had never dawned on me before. Indeed, it maps onto the very reason one uses a log pot in the first place: upward and downward adjustments anywhere in the full range of amplitudes should be perceived as gradual, and log does that...across the entire range.

    So, if one is building an amp, you bet your bottom dollar that a log volume pot is essential since the level will be adjusted in all sorts of ways, but mostly in the middle of the volume range and below, with noticeably less use in the top range. This is completely different than a guitar volume pot where the default is full volume, and adjustments are generally only in a downward direction.

    As I am fond of saying, context is everything, and something that may be ideal for one context may be pointless or even antithetical to another.

    Nice post, Steve. Great idea. Where's that thumbs up icon when I need it?

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    Senior Member Guitarist's Avatar
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    Hammer's dual range tone pots has worked great for me recently. I actually took a few apart and opened the half way point with a circular dremel disk so center opens the tone bleed altogether.

    The top center of the resistance trace is scratched off:

    Ω

    I used a 250K audio so each tone circuit sweeps evenly across about 100K. This get you tone roll-off quick enough. While they were apart, I should've dinted the pots at the zero point so it's more set and forget.

    I wonder where else these could be used.

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    That's clever what you did with the dremel. Essentially two no-load tone controls in one pot! I should try that since I find the lack of a centre detente a little too attention-demanding for my tastes.

    As for calling it "Hammer's dual range tone pot", the original idea was actually in an article by Craig Anderton on tone controls in Guitar Player about 30 years ago. All I've done is trumpet its virtues and suggest some component values. But thanks for the nod anyway.

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    Junior Member phfobric's Avatar
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    Craig Anderton - Mandrake Memorial!! ooooo I'm o-o-o-old...if this thread isn't completely dead...I am reconfiguring an HSS to a HB and two stacked coils. It's got the master (1 vol, 1 tone) going out and it being a HB environment, conned myself into thinking I needed to get 500k's. Where's the debate (or thread) on this? And I'm taking out a .022 cap; what's the consensus here on to what put back with the different pots?

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