Audio taper volume pots

RLee

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I just finished rewiring my LP std with CTS 500k pots, 50's wiring, PIO caps... I'm happy with the results (will have some clips at some point), but if I had it to do over again, I would have gone with linear pots for the volumes. I'm not sure why others prefer audio taper for volumes -- I see now why gibson puts linear in by default. With audio taper, the volume rolls off to nothing in the first half of rotation, about half of the pot range is wasted, since when your volume is at 10, you're at the fast end of the taper.
Hopefully I just need to get used to it, don't really want to replace it immediately.
 

Boppy

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I sometimes do quick volume swells for individual notes to get that "attackless-sound."
I use from zero to about 20% travel on the volume knob to accomplish this. It sounds like audio-taper pots for volume would really hamper that technique. Thanks for the heads up.
 

korus

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put a resistor of 100k-220k across 2 non grounded lugs - the lower the value of the resistor closer to linear pot's taper gets - this resistor will make the curve less steep

just try it. it's cheap and easy to put in (and to put out if needed)
 

RLee

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The parallel resistor defeats the purpose of going from a 300k pot to 550k... it loads the pickup differently. If I don't get used to it I'll just get a linear 550k to use. It just surprised me that many recommend the audio taper volume, since IMO it's less usable. It works well in the tone position, however.
 

MATTM

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What type of CTS audio pots did you install?
 

BrazenPicker

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That sounds wrong to me. This is exactly what an audio pot is supposed to avoid. Our ears don't perceive loudness in a linear way either and therefore a true linear pot will give us a poor result.

For instance, 4 people whispering at 30 decibel each won't sound as loud as 1 pneumatic drill at 120 decibel. Likewise, four 25W lightbulbs won't seem as bright as one of 100W. If you regulate the power in a linear way, your ears/eyes won't perceive the change in loudness as "linear" at all.

If you look at the chart below, a linear pot would do exactly what you say. If "10" on your volume pot were the 120dB (inside ship's engine room) then "5" would be 60dB "a quiet conversation in a room", and everything below that gets really quiet.

graph_1_2_b2.gif


Could it be that somehow your order got screwed up and you got linear pots? If you have a multimeter you can check the taper, although you'll have to unsolder the wires first to disconnect the rest of the circuit. If the "5" position gives you exactly half the resistance as the "10" you have linear pots, which is what you don't want. Audio pots (aka logarithmic pots) compensate for the nonlinearity of our hearing. Or possibly you have logarithmic pots and the taper happens to be particularly poor.
 

chipper

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Yep, I got the same results when I put in CTS 500K Audio Taper pots for the volumes.

Problem solved when I swapped them out for linear tapers. My tones still have the audio taper pots, but they work fine.
 

Quill

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I'm wondering along with Brazenpicker on this one. The results seem kind of backwards! Half the travel almost useless? "... the volume rolls off to nothing in the first half of rotation, about half of the pot range is wasted, since when your volume is at 10, you're at the fast end of the taper" - so you're saying that all the action is in the top half of the pot. Curious; my experience with linear taper pots is that all the action appears to happen between 0 and about 3, then there's not much perceivable difference after that ... yours are doing the same sort of thing, but at the other end of the wiper? Weird.

Well - not sure what they are; a combination of linear and logarithmic, probably - but RS Guitarworks sells a guitar potentiometer (specifically, a volume pot; they don't recommend it for a tone control) that has a nice, smooth taper. It has the effect of a very even increase in volume from one notch on the dial to the next. They are quite good for controlling a sensitive tube amp.

Shame to do all that fussy work and have it not be right. At least it's not a 335 ...
 

wulfman

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I just rewired an Epiphone Elite 50's style with audio volume pots and had the same experience. There is just too much drop from even 10 to 8 for me.
Could it be that the 50's wiring accentuates this "problem"?
 

RLee

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Could it be that somehow your order got screwed up and you got linear pots?

No... remember I had stock gibson linear pots in before, and the adjustment range was very nice and gradual.

I'm aware of the engineering applications of log/audio tapers, and they are normally used in the opposite direction, ie, you start out at the slow end of the taper, and as you rotate the control, the rate of change increases. But with the volume pot on guitars, most start out at 10 and go the other way, therefore you are starting out at the max rate of change on the taper, thus your volume decreases way faster than a linear pot. The extreme side of the taper is not normally as useful a range; for example, in a stereo system volume control, the normal adjustment range is from around 2 to 6 or 7, and in this range, you DO get a nice transition; but the extreme edge of the taper at 10, to about 7, is super fast and does not allow for fine control.

Mind, if your desire is to get more volume change faster at that end, which would be useful for things like volume swelling, then it works great. Who knows I may get used to this and like it.

As I mentioned, it's apparent to me now why gibson puts linear pots in their guitars for volume. It gives you fine control over the volume in the range of 10 to 4, which is the range most used.

The pot I have in there is fine -- it's working as designed. It's just that with that taper, the volume is 90% reduced at around 6, which means I only have less than half the pot to work with now for volume, where before almost the entire range of the linear pot was useful.

Again, I may grow to like it -- it means I can get bigger changes of volume with very little movement, which may prove useful.
 

RLee

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I'm wondering along with Brazenpicker on this one. The results seem kind of backwards! Half the travel almost useless? "... the volume rolls off to nothing in the first half of rotation, about half of the pot range is wasted, since when your volume is at 10, you're at the fast end of the taper" - so you're saying that all the action is in the top half of the pot. Curious; my experience with linear taper pots is that all the action appears to happen between 0 and about 3, then there's not much perceivable difference after that ... yours are doing the same sort of thing, but at the other end of the wiper? Weird.

What you guys are missing is that the taper is being used backwards. You can actually get reverse taper parts for cases where you adjust from max to min. But that would be too gradual in this case. The linear seemed to actually have a good rate of change.
It's not that the new taper is all bad, don't get me wrong... I'm just not sure I like it yet. As I mentioned, it would be great for volume swelling, much less work than before.
 

BrazenPicker

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I have a bunch of Bare Knuckle spec'd audio pots (made by CTS) lying around that I want to install as soon as some shielding materials arrive that I ordered in the mail. Will report on those hopefully by next weekend.

If what you're saying is true (reverse end of the taper) a custom spec'd audio pot like BKP's or RS's will have taken this into account I'm sure. The only reason I went with BKP is that their shipping is quite a bit cheaper when ordering from abroad.
 

korus

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first LINEAR TAPER - 50's wiring makes vol pots taper steeper. That's why linear pot used as vol pot is not linear any more and sound more usable. but the same linear taper pot used as vol in modern wiring is ... pretty unusable (almost no change until ~3), just as stupid as using linear taper pot for tone pots. sure, vol pot is voltage divider and tone pot is a variable resistor but bad taper is bad taper

now let's go to the other side - AUDIO TAPER - most common audio or logarithmic pots are those with the 10/90 curve, which is already pretty steep for volume pot in modern wiring (~7 most of the signal gone). if you put that regular audio taper pot into 50's wiring it will be almost stupid 5/95 curve ... bad replaced with worse

now serious stuff: Tapering resistor will not defeat change from 300k to 550k. With vol pot on 10 signal will still see 550k resistance between hot and ground. The thing that WILL change is the taper becomin LESS STEEP and by this it will make the usable range of the pot greater. Just draw it and think once more time before replying.

The very idea behind the invention and making of custom taper volume pots for guitars (RS Superpots, Dr.Vintage, DiMarzio, Hammer and now finally CTS TVT posts) is to have a taper which is not linear (50/50) and not regular audio (10/90) but somewhere IN BETWEEN these 2 'extremes' - making the curve somewhere in the range from 25/75 to 35/65. That is what old Centralabs had, that is what works for most people, and that is what sells custom taper volume pots to those who tried them at least once.

With tapering resistor used on cheaper regular audio pot one can tailor pot's taper/curve for what he likes. The only difference is that the lower you go with that pot with tapering resistor it will loose slightly more HIGHS than the custom taper pot with the ~ same curve but without tapering resistor, but trust me - difference is small and effect of better taper is overwhelming no one notices or cares. and we can always entertain ourselves with some math ... but, remember on 10 it is still the same tone.

it takes 1 resistor, 2 aligator clips and 3 minutes to test it.

HTH
 

BrazenPicker

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It made sense about that taper resistor once I drew a diagram, will keep that in mind if I ever need it. That should slow down the speed at which the volume drops off as you go from 10 to below.
 

RLee

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...Tapering resistor will not defeat change from 300k to 550k. With vol pot on 10 signal will still see 550k resistance between hot and ground.

With tapering resistor used on cheaper regular audio pot one can tailor pot's taper/curve for what he likes. The only difference is that the lower you go with that pot with tapering resistor it will loose slightly more HIGHS than the custom taper pot with the ~ same curve but without tapering resistor, but trust me - difference is small and effect of better taper is overwhelming no one notices or cares. and we can always entertain ourselves with some math ... but, remember on 10 it is still the same tone.

it takes 1 resistor, 2 aligator clips and 3 minutes to test it.

HTH

I appreciate the suggestion, but you must see that it absolutely does negate the entire reason for going from 300k to 500k. Logically, the point of putting the resistor there is so that when you adjust it away from 10, the taper is better, therefore, the fact that the load resistance is unchanged at 10 is kinda moot, right? At about 5, the load that the pickup sees is going to actually be LESS than what it was with the 300k pot. What you are doing with the resistor is trading min/max range for taper, and I'm not willing to give up max range, because that's why I changed to 550k to begin with. :)

I'll either get used to it or I won't, it's an easy change if I decide to go linear or custom taper. My point here was that I was surprised that people generally recommend this change (linear to audio).
 

korus

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I appreciate the suggestion, but you must see that it absolutely does negate the entire reason for going from 300k to 500k. Logically, the point of putting the resistor there is so that when you adjust it away from 10, the taper is better, therefore, the fact that the load resistance is unchanged at 10 is kinda moot, right? At about 5, the load that the pickup sees is going to actually be LESS than what it was with the 300k pot. What you are doing with the resistor is trading min/max range for taper, and I'm not willing to give up max range, because that's why I changed to 550k to begin with. :)

I'll either get used to it or I won't, it's an easy change if I decide to go linear or custom taper. My point here was that I was surprised that people generally recommend this change (linear to audio).

If it was only for calculation/math regular audio 10/90 taper would do, but we all know that it does not. So just put aside knowledge for a while and use experience. Just put the poor resistor in on that audio vol pot a play a guitar with it, without calculating load or anything else. Load is just a number and tone is not. Also, this resistor test is far easier to implement than replacing the pot. If it were wired modern 150k would be optimal but since it is 50s, you can go lower - 130,120 even 100k.
And you can always replace pot(s) later on.

Been there done that - over-thinking, predicting and all that mind & ego exercises. Trust me and skip that just once and just try it. If you can, that is. And if you can not, it's ok. I've done my part.

http://www.mylespaul.com/forums/ton...fused-gotta-stop-drinking-over-breakfast.html
 

RLee

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Again, appreciated, but I'm not looking for an interim easy workaround, although putting the option out there for anyone that can use it is good. I'll either decide to keep the pot, or replace it. There's no mystery or overthinking on my part, I'm well aware of the technique and the ramifications.
 

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