Vol knob basics.

[Chuck H]

For the most part tone pots are just like that. Using a lower pot value would affect your "everything full up" tone by reducing the resonant peak. So you don't want that if you like it bright. I vaguely remember from an earlier thread that you might have had a linear pot for volume (since changed to the new Alpha audio pot) and an audio pot for tone reported for that guitar. If you want more change 10 - 5 and less from 5-0 then an audio pot is what you want there. Please check to see what taper the tone pot in your guitar is now.

[Sea Chief]

For the most part tone pots are just like that. Using a lower pot value would affect your "everything full up" tone by reducing the resonant peak. So you don't want that if you like it bright. I vaguely remember from an earlier thread that you might have had a linear pot for volume (since changed to the new Alpha audio pot) and an audio pot for tone reported for that guitar. If you want more change 10 - 5 and less from 5-0 then an audio pot is what you want there. Please check to see what taper the tone pot in your guitar is now.

You're memory is remarkable! indeed I do have an audio taper 500k in the tone pot. Ah so as I don't want it brighter, I stick with the same value then. I hope to get a bit more goodies via a better Alpha pot.

So if I put a B500k in the tone, it would do something akin to what my vol pot used to do? last section of rotation for majority of the scope-?

thanks SC

[Chuck H]

Ah so as I don't want it brighter, I stick with the same value then.

If you DO want to take a little brightness off of the "everything turned up full" tone you can change to a 250k audio pot. That would also have a more intuitive adjustment along it's rotation. If you DO NOT want to take any brightness off of the "everything full up" tone then you have to stay with the 500k value.

I hope to get a bit more goodies via a better Alpha pot.

I'm sorry, but I wouldn't expect much difference going to the Alpha pot. They actually have a taper based on two linear tangents. Which is the same as any cheap pot. In fact that's what nearly ALL pot manufacturers do anymore. Cheap or expensive.

So if I put a B500k in the tone, it would do something akin to what my vol pot used to do? last section of rotation for majority of the scope-?

Yes. A linear taper pot would make the problem worse.

[Chuck H]

Ok, I'm about to explode your brain again. I came up with a solution for your problem. A Bournes 16mm 250k "guitar" pot (which has a 10% taper). Modify it as a "no load" circuit (easy to do). Then use a 510k resistor from the no load lug to the ungrounded end of the tone cap to simulate the 500k resistance you have now. Boom! It gives a much better taper and has the same tone as a 500k pot when the knob is set full.
The only added difficulty would be that you'd need to take the back off the pot to scratch the track and then wire a 510k resistor across the two outside lugs. Easy peezy.

[Sea Chief]

Hi Chuck H you exploded my head before the Bournes suggestion! oh yes. The graphs.. I have not a clue how to distinguish between, nor how to consider where the lines of one graphs are relative to the vertical axis (dB) & glean anything from any point of any line of it ! haha. I'm again totally lost at sea.

I can only distinguish a tiny difference of the lower graphs pink line, lower lines, are a fraction leftwards, of the graphs above. But what that signifies, if its the only difference.. I couldn't even aim a wild guess at. There is some significance of where they dip down & hit the lower axis-?? that's my best guess.

So I'm studying the graphs. I read the axis 'dB' incriments. I see the lines. I notice a difference (so I'm trying my best, not being a lazyass!!) it's just a language that I have not studied, like gain, so have no way of comprehending).

You are very kind though- that is all I do know! appreciated, SC.

[Chuck H]

For now just think of each line on the graphs as representing each number on the tone knob. Which is how I plugged in the numbers actually. So the bottom line is zero on the knob and the top line is ten on the knob. So these lines would be the same on all three graphs. It's the 1-9 lines that show the taper. The dB range is, as you know, a measure of signal amplitude. I know the differences look subtle, but they're not. Just 3dB change represents a difference of twice/half power respectively. The actual lines are relative to the frequency markers at the bottom and are an approximation of your guitars signal. So you can see the resonant peak at knob ten in each graph and you can see the cut at that frequency of about 36db at zero on each graph. Knob position five is demarcated on each graph to help show the gradient of change.

I hope that helps. But even if it doesn't I've come up with this circuit which I think will give you, or anyone for that matter, the most intuitive results for tone knob settings. If you're interested in that.

[Sea Chief]

For now just think of each line on the graphs as representing each number on the tone knob. Which is how I plugged in the numbers actually. So the bottom line is zero on the knob and the top line is ten on the knob. So these lines would be the same on all three graphs. It's the 1-9 lines that show the taper. The dB range is, as you know, a measure of signal amplitude. I know the differences look subtle, but they're not. Just 3dB change represents a difference of twice/half power respectively. The actual lines are relative to the frequency markers at the bottom and are an approximation of your guitars signal. So you can see the resonant peak at knob ten in each graph and you can see the cut at that frequency of about 36db at zero on each graph. Knob position five is demarcated on each graph to help show the gradient of change.

I hope that helps. But even if it doesn't I've come up with this circuit which I think will give you, or anyone for that matter, the most intuitive results for tone knob settings. If you're interested in that.

Hi there Chuck. Ive put aside time to try going over these graphs, your last post, try everything I can to understand as much as I can. Determined to.

Ok I read it 4x & I get a headache, because Im literally straining to comprehend even the bare bones of it. As such I cannot make headway. Ive just come to think that your "1-9 lines" might, or perhaps even must, refer to the lower axis. Because there are three sets of, it seems, 9 lines. But this is a 'SC logical' guess. And why three sets.. is a percentage of my headache.

Your 1st sentence, I think/ again more guessing, refers to the vertical axis. I see there is a hump in the pink lines, so 'resonant peak' might, I can only surmise, have something perhaps relating to this. What this is, is a further proportion of my headache.

So even for me to get this far.. an hour! What then the pink lines are (tho 'knob position' gives me a clue), why 11, how three graphs relate to each other, what knob 5 position is with 5 to the left of it and 5 to the right (which makes 11.. I can only think spinal tap here as any form of abysmal anchor to grab onto, so adrift I am), what frequency markers could be.. I think shows you what a hopeless a task this is to teach to me!! I can only apologise for my utter ineptitude & bow to your your intellect, & patience. I am an idiot ich bin ein idiot (& if you want me to write this in latin 1000x as penitance.. I shall do so. On my ipad).

Thanks so much- SC

[Chuck H]

There are 11 lines because the knob at "0" position is indicated. 1 - 10 + one extra indication line would be 11.

You've identified the resonant peak correctly. It's a phenomenon that results when an inductor (your guitar pickup in this case) and a capacitor (your guitar cable has capacitance) react. And it's a signature sound for electric guitar. It's the first thing to go when the tone knob is turned down. And, incidentally, the first thing to go when the volume knob is turned down.

[Sea Chief]

There are 11 lines because the knob at "0" position is indicated. 1 - 10 + one extra indication line would be 11.

You've identified the resonant peak correctly. It's a phenomenon that results when an inductor (your guitar pickup in this case) and a capacitor (your guitar cable has capacitance) react. And it's a signature sound for electric guitar. It's the first thing to go when the tone knob is turned down. And, incidentally, the first thing to go when the volume knob is turned down.

Hi Chuck. So was I right that your "1-9 lines" refer to the lower axis? (if so, why are there 3x sets of them-?) A guitar cable as a capacitior.. is a new one one me, I wouldn't know how this information is of relevance though after considering your sentence including the inductor with as much thought as I can. Ok if Ive located the resonant peak, what this 'signifies' isn't known to me though, so again it sits just as an arbitrary existance to me. Until I can get some meaning to the pink lines, & something apart from looking very similar to each other on 3 graphs.. again I'm left flondering with incident after incident of purely arbitrary information.

I just don't think I'm capable of understanding the graphs, if the significance of every bit of them is still a country mile away after your patient explanations, unfortunately. In fact the more you explain, the more I cannot understand!! (eg above, 'the volume knob is turned down..' & for both knobs, is like the final knockout blow: I have so little conception of what is being said, I stare out the window & start dribbling). All I have understood is the mountain looking thing.. is a 'resonant peak'!! IE an image!! (its an artistic brain meets mathmatics instrinsically the issue I believe). thx SC

[Chuck H]

lines 1 through 9 would be all but the top and bottom lines on each graph. The top and bottom line on each graph is the same because they indicate 0 and 10 respectively. Which is the same in all instances. Maybe I was unclear about that.?.

The guitar cable being a capacitor is relevant because of how it reacts with the inductance of the pickup to create the resonant peak.

The resonant peak is relevant because it's an isolated frequency band that is at a peak. This is an equalization characteristic that is audible.

There are three graphs because they represent three different circuits. One is a 500k linear taper tone pot. The next is a 500k audio taper tone pot and the last is my modified 250k audio taper tone pot. I labeled them in the hope that it would be obvious.

The information is not arbitrary. It is just not understood by you. That is not an indication that what I've demonstrated is arbitrary.

But... If what I've shown in the thread so far in the way of explanation is not understood, that is of no consequence to you unless you still want to understand it. Otherwise it is enough for you to know that the circuit I've designed, demonstrated in post #34, will give you the most player intuitive tone control.

Information given so far that I'm sure you can understand includes:

500k tone pots have an inherently poor adjustment along their range. And linear pots are worse than audio pots in this regard.

250k tone pots will have better adjustment along their range. And an audio pot is better than a linear pot in this regard. But...

A 250k tone pot will change the guitars tone by reducing high frequencies. For better or worse depending on what the player wants.

The circuit I've offered in post #34 will give you the tone of a 500k tone pot but has the adjustment range of a 250k pot.

This should be enough information. It's not important from a player perspective to understand why something works. That's for the nerds that design the stuff. For a player it's only important to understand THAT it works. So like I said, unless you REALLY want to understand what the circuit is doing at the electronic level you have the option of simply knowing what it will do for you as a player. And that has been covered and is outlined in the bold type above.

You've recognized the problem with 500k tone pots from a players perspective. I've shown how it can be fixed. I did this from a nerds perspective because that's what this forum is for. Hopefully the information I've given that YOU don't understand is RELEVANT to other readers.

[Sea Chief]

lines 1 through 9 would be all but the top and bottom lines on each graph. The top and bottom line on each graph is the same because they indicate 0 and 10 respectively. Which is the same in all instances. Maybe I was unclear about that.?.

The guitar cable being a capacitor is relevant because of how it reacts with the inductance of the pickup to create the resonant peak.

The resonant peak is relevant because it's an isolated frequency band that is at a peak. This is an equalization characteristic that is audible.

There are three graphs because they represent three different circuits. One is a 500k linear taper tone pot. The next is a 500k audio taper tone pot and the last is my modified 250k audio taper tone pot. I labeled them in the hope that it would be obvious.

The information is not arbitrary. It is just not understood by you. That is not an indication that what I've demonstrated is arbitrary.

But... If what I've shown in the thread so far in the way of explanation is not understood, that is of no consequence to you unless you still want to understand it. Otherwise it is enough for you to know that the circuit I've designed, demonstrated in post #34, will give you the most player intuitive tone control.

Information given so far that I'm sure you can understand includes:

500k tone pots have an inherently poor adjustment along their range. And linear pots are worse than audio pots in this regard.

250k tone pots will have better adjustment along their range. And an audio pot is better than a linear pot in this regard. But...

A 250k tone pot will change the guitars tone by reducing high frequencies. For better or worse depending on what the player wants.

The circuit I've offered in post #34 will give you the tone of a 500k tone pot but has the adjustment range of a 250k pot.

This should be enough information. It's not important from a player perspective to understand why something works. That's for the nerds that design the stuff. For a player it's only important to understand THAT it works. So like I said, unless you REALLY want to understand what the circuit is doing at the electronic level you have the option of simply knowing what it will do for you as a player. And that has been covered and is outlined in the bold type above.

You've recognized the problem with 500k tone pots from a players perspective. I've shown how it can be fixed. I did this from a nerds perspective because that's what this forum is for. Hopefully the information I've given that YOU don't understand is RELEVANT to other readers.

Hi Chuck,

sorry it's arbitrary -only- from my perspective. If that means it cannot be arbitrary.. then my choice of vocab was wrong.

I choose to understand, please don't conclude that I don't want to, or don't choose to (I said: I spent an hour going over the graphs until it induced a headache). This is inherrantly incorrect. I absolutely choose to. I'd love to be able to! But, as much as your efforts, patience, & fantastic info provides.. I just cannot understand almost all of it. I can only apologise.

I knew the 3 graphs, labelled differently, are there to represent the different types of pot, this is of course understood (because labelled so). But I cannot tell difference between their "many strange pink lines" therefore 'they seem to all intents & purposes, indistinguishable to me' I should have said. Unfortunately they just remain "strange pink lines floating in space" with a series of 3x 9 'strange sections' along the bottom with kHz designating the axis: I have -no clue- what this axis is, why its in 3 sections, what kHz signifies, nothing. Frequency is a pitch of a note, isn't it-? (is all I can add). This right here, may give an indication of how lost I am.

Your bold-type "fundamentals" which to you are clear that I should at the very least understand.. I cannot understand any of each (eg 'adjustment' again [to me] is an entirely 'arbitrary' word: I just don't understand what is being adjusted, or has done, or will do, or might do if..). I think a pot is inherrantly an 'adjustment device'.. but whether this is what you're referring to (I'd think highly likely not with my luck). I've never been so info-snowed-under & unable to cope! algebra at school maybe.

Schematics which I'm bad at, are a mile more understandable than this. I can see one thing connecting to another in a schematic, & if it has a symbol, I can go to a symbol chart & see what it is. Thanks SC

--

[Fluoroscope 5000]

I find Chuck's explanations and graphs very clear, but that's because I already understand all the relevant aspects. Not understanding it is no reflection of intelligence or human value. So, there's no need to berate yourself about it, and doing so might just make it harder to for you to understand. It's actually not as complicated as it looks. Maybe clearing up a few points will help?

kHz = 1000 x 1Hz, so 10kHz =10,000Hz. The numbers on the bottom of the graph represent the freq spectrum from 10Hz to 10kHz. The vertical lines follow the sequence from 10, 11, 12... and are spaced in a way that works better for graphic representation or something (someone else might know the reasoning, but it's of no major concern).

You may be confused by the fact that there are two peaks in each graph -- one being at a much lower freq than the other. The strongest higher freq peak represents the tone knob at 10 and is determined by the cable capacitance value in relation to the pickup inductance value b4 the first preamp stage. The strongest lower freq peak represents the tone knob at 0 and is determined by the sum of the tone knob cap + the cable capacitance values in relation to the pickup inductance value b4 the first preamp stage. Therefore, the pink line rolling off at the lowest freq corresponds to the strongest lower freq peak, and the pink line rolling off at the highest freq corresponds to the strongest higher freq peak. The pink lines in between are just steps on the tone knob between the two extremes. At some point down the tone knob sweep (depending on the resistance taper) the cable capacitance is no longer the dominant capacitance factor, so the peak is then determined by the sum of both capacitance values. The bottom three pink lines are the furthest apart on the 500k linear taper pot graph, representing the most extreme change from o to 2 on the knob. The bottom three pink lines are closest together on the 250k audio taper pot graph indicating the most linear tonal sweep of the three graphs.

The capacitance of a guitar cable is usually much lower in value than the tone knob cap, but not always. It should be noted that the higher freq peak in each graph is in the middle of the most sensitive human hearing range of 3-3.5kHz and will result in the most ear fatigue at high volume levels. In that case, I would use a lower capacitance cable to smooth out and raise the peak up into the 4kHz + range, but sometimes "there's a fine line between pleasure and pain".

Incidentally, my S-type guitar knobs all show 1-10 with no "0", but that's of little consequence.

The inductance value listed for the Fender CS Texas Special Tele bridge pickup can't be even close to correct unless it's wound with ~44AWG wire.

The value measures in this post for the set are more likely correct. Yes, I don't trust Fender to have supplied the correct inductance values:

Measured Electrical Values of Various Telecaster Pickups

Chuck's idea to alter an A250K pot is pretty cool, but I wouldn't bother. A500k pots should be good with a dark pickup set like that (the neck pickup likely has a brass cover -- making it that much darker sounding. I would use a very low capacitance cable to get a peak on the bridge TS pickup above 4kHz when the tone knob is up. Sommer Spirit XXL cable is the lowest capacitance cable for the money now at 52pF/meter. I'd go with 10-12' of that with HICON noiseless plugs. I have 10' with those plugs and it's quality German-made stuff. The bridge pickup may be fairly bright, but should have a nice bell-like articulation and not be piercing. You can also brighten the neck pickup a bit by removing the cover if you want.

Lastly, the 1100 Gauss measurement is actually pretty high. An old Fender employee apparently told John Suhr they used a weaker/softer A5 magnet from some point in the early '60s on so they didn't have to bevel the edges to hide the chips. It might be worth weakening the poles to ~600G to get a sweeter tone with less harmonic modulations at higher pickup coil settings (which increases fundamental note strength = warmer note timbre). Here's a post on how to do that:

Degaussing, or "aging" AlNiCo pole pieces

I hope this helps clear things up. Maybe read it again later if it just makes your headache worse now.

[Chuck H]

BOOM!!!


That was Sea Chiefs head exploding. I hope you're happy with yourself :-/

[Sea Chief]

Fluoroscope 5000 very grateful for this. I will need all weekend to try digest it, not just reading twice.. morelike 10x as I do with Chuck's posts!

One thing I cant understand, is if we're talking tone pots, why the vertical axis' denomination is in dB. Vol knob, yes I understand this would be used vertically, because vol is relative to dB. But a tone pot.. has no bearing on volume, just the high & low frequencies differ. In that respect it should have only one axis then (this is my reasoning/ how my head works). And conversely, why a kHz designation along lower axis.. for a vol knob if this has not bearing on the pitch of notes.

So you see my head head has exploded.. before I even get onto the alien pink lines already!!

You see if I'm stuck on what & how & why the axis are, sort of 1st thing on pg1.. I'm not really in a fit state to understand anything further onwards surely.

The irony here not being lost on me too; the thread title being Vol Knob Basics.. & I seem to have gone into a wormhole of vol knob relativity theory! (but I can see all this being basics to many, yes I appreciate this is likely).

Chuck H no Im not happy w'myself- I feel thick & the shame makes me wail & my teeth to gnash. SC

[pdf64]

You understand a frequency response chart, right?
ie a flat horizontal line will be an even balanced tone. If it goes up or down at the right end, the tone will be brighter or duller. Up or down at the left end will be bassier or thinner.

So, the charts are the frequency response of the guitar’s signal.
The different control arrangements / settings elicit a different frequency response, and hence a different pink line trace on the chart.

I’m reminded of when I first started trying to play guitar, and just couldn’t grasp the concept of what was meant by the ‘key’ that a song was in.