software

I want to get a little better understanding of how tone pots really work. I tried to Google up some help, but didn't find what I was looking for.

Here it goes:
With the tone control on 10, there is the least amount of signal/treble leaking off to ground through the TP (tone pot). Set at 10, signal leaks out that the rated tone pot resistence will allow, 250k, 500k, 1M, or whatever. With the TP on 1 it is allowing a the maximum signal/treble bleed as the TP will allow. Let me see if I am getting this part right. On a relative scale when set on 10, the TP of 250K still allows a little bit of bleed. The 500k permits less, and the 1M lets the least bleed. A no-load, TP allows absolutely no bleed off the signal. With the TP on 1, how much signal loss does the pot allow.

Now, am I understanding tone pots correctly? Thanks for your kind help.

I would like to see a graphic illustrating what the guitar signal looks like with the tone on 10 versus 1. What does treble really mean to a tone signal? Do yo think I would learn anything from this kind of information? I think I might.

the size of the cap in the tone circut has alot to do with what frequencies you are rolling off.

you pretty much have it there. i have no idea where to find the graphic but id be curious to see it

Think of a capacitor as a frequency dependent resistor. As frequency goes up, the cap's resistance goes down. In other words, they pass high frequencies. The smaller the cap value, the less lower frequencies it passes; the higher the cap value, the more lower frequencies it passes.

Now, add in the tone pot, which is wired up as a variable resistor added to the cap. A 250K tone pot on 10 will swamp the effect of the cap at the higher frequencies. On 1, the cap dominates the resistance at most of the frequencies because the pot's resistance does little to the resistance of the unit.

The pot will start to roll off frequencies at the top end, and as the tone pot is turned down to the middle ranges, there will be a leveling off of the upper frequency rolloff where the pot's resistance again begins to dominate the cap's resistance, and eventually at zero, you have a big ole' cap rolling off your top end.

The (free) duncanamps.com tone stack calculator might be able to show you some of that if you tweak around with some of the values. Or if you want to calculate the numbers by hand, the equations are:

R = 1 / (2 pi C f) with C in Farads and R in ohms...my shorthand is

R = 160 / C f with C in uF and R in Kohms

...and don't forget that the calculated R is in parallel with the volume pot in standard wiring or with the lower part of the volume pot in the 50's mod wiring.

HTH!

A tone control is basically an RC (resistive/capacitive) low-pass circuit, that is variable. The quot;graphicquot; you are speaking of would be difficult to produce, because there are really three variables:
1.Frequency
2.Capacitor Value
3.Resistance (Variable)

A Bode plot works nicely if you have a set value for R and C, it lets you see the roll-off of frequencies. Here's a link that let's you set the R, C, and freq. (Use 47nF for .047uF, somewhere around 500K Ohms for Tone at 1 and 0 ohms for tone at 10, then select the frequency.

from : localhost/ interesting thing to note is that even if you are playing a note (say A 440Hz) it's the overtones that actually give the guitar it's tone. You can see that there really isn't much roll-off at the fundemental (you want the same overall volume) but at higher and higher harmonics it's greatly reduced. (This program doesn't take into effect the bleed off when the tone is at 10, this only uses one R instead of 2 constantly variable R's like a pot really is.

EDIT - you beat me to it, Chill... I like your description better anyway. I'm terrible at technical writing. lol

Great stuff Chill and PFDarkside-You have provided some high quality information. Thanks for spelling it out for me so well. Those are some great contributions and terrific information sources you provided. The Bode plot is just what I needed. That's a lot for me to digest.

Let me rephrase it to see if I'm getting it...Very generally, higher frequencies have higher energy, therefore the caps and pots function as adjustable energy Hurdles. High hurdles only allows the higher frequencies to exit to ground. Lowering the hurdles allows lower energy frequencies out. I need to think and look at that low pass filter link to gain a fuller understanding between the pot resistence and the caps rating. I think I'm gaining ground on this thanks to you guys. It's greatly appreciated.

I can't improve much on what everyone else has said . . . but I hate to miss an opportunity to post a pic.

Sometimes it helps to look at a circuit from what we call an quot;equivalentquot; circuit. Strip it down to its basics, and show variable components as if they were hard-wired to one setting. So we get this with some random settings:
The volume control is a quot;loadquot; on the entire pickup. The tone control is a quot;selective loadquot; on only the high frequencies - with those frequencies determined by the value of the cap. The degree to which we dump them to ground, determined by the setting of the tone pot.

Artie

btw - For the sake of simplicity, I assumed linear controls.
One last edit: If I make my tone cap so high that it passes all frequencies, .1uf for example, it becomes another volume control.

I haven't been using these terms right: Volume is a load? I thought that signal/current from the pups was the load. Like this: a loaded circuit is a circuit with current. And that Volume and tone pots were variable gates, no?

And the tone CAP is really what determines which frequency get shed to ground?