Newbie wiring questions

[bcbeak]

What is the difference between a Tone and Volume POT?
Aren't they both audio tapers? How is one made into a Tone pot?

Capacitors .. I can't read them. Is there an index somewhere that explains the values?

[Russinator]

Most tone and volume pots are identical, and yes, audio taper. What determines whether it's a tone or volume control depends on it's use and circuitry.

there are several codings or plain text on capacitors. Usually the code will look something like 473 which means 4 is the first significant figure, and 7 is the second, and 3 is the number of following zeros.

Offhand I don't know where a reference can be found. Try Google, or I'm sure someone else knows.

[Will V.]

Basically, there are two ways of measuring caps, those that are used in guitars- microFarads (uF or μF), and picoFarads (I just use pF, but I'm not sure if that's right). One uF equals 1,000,000 pF.

Capacitance measured in microfarads is usually expressed as a decimal, common values for guitars are .022 uF, .047 uF, .05 uF, and .1 uF.

Capacitance measured in picofarads is usually expressed as a base number, with a multiplier. The same values above, 223 (meaning, 22,000), 473 (47,000), 503? (not sure I've encountered that one before, 50,000), and 104 (100,000).

Voltage ratings are pretty irrelevant to guitar caps, except that the higher the capacitance and the higher the voltage rating, the larger the cap will be. They can get too large for control cavities.

[Kevin]

As noted before, both tone pots and volume pots are the same thing. The addition of the tone cap, and the wiring, itself, is what differentiates a tone pot from a volume pot.

A tone cap is a capacitor connected to a potentiometer on one end and a grounding point on the other. The capacitor serves as a sort of high-pass filter (i.e., it lets the high frequencies pass through, but blocks the lower frequencies). The amount of highs it allows to pass depends on the value of the cap.

"But, wait," you say. "I thought it killed the highs. Now you're saying it lets them pass." Yes; it allows them to pass, but they pass through to ground, effectively killing them.

Basically, you tap off your volume pot and send the signal to the tone control. The tone pot -- unlike a volume pot that sends the entire signal to ground as you roll it back -- sends only the high frequencies to ground as you turn it down.

The "proper" value for a tone cap is a matter of opinion. Fender used to use .05mf caps in teles and .1mf caps in strats. Now they use .022mf caps in the newer models and .the old values in the vintage reissues. Some people prefer the .022, some prefer the .047, and some go as low as .01. The higher the value, the more highs are rolled off. I tend to use .047mf caps with single coils and .022mf caps with humbuckers.

Another thing that some people do with caps is use a very small value (e.g., .001mf or lower) cap across the hot lugs on their volume pot as a treble bleed circuit. This will enable you to keep the high frequencies as you roll off the volume. The value is, again, subjective, and at times I've just used a cap and other times used a cap and resistor in series. I usually have to experiment with a bunch of different combinations until I find the one I'm looking for. This is a mod that some people love and others hate.