Tone pot acting like a volume control.

[Jesse Slater]

I just installed a set of Phat Cat pickups. I followed the Phat Cats 2 volume 1 tone 3 way toggle diagram. The pickups sound great but the tone pot is acting like a volume control. This is not the first set of S/D pickups that I have installed. I can't figure out what is going wrong. Need some help please....

 

[JB_From_Hell]

Re: Tone pot acting like a volume control.

Post a few good pics of your wiring job (particularly the offending tone pot) and somebody will diagnose it pretty quickly.

 

[Artie]

Re: Tone pot acting like a volume control.

The #1 cause of this is missing a "zero" in the tone cap value. For example, using a .22 uf instead of a .022 uf, will cause this symptom. Check that 1st.

 

[Jacew]

Re: Tone pot acting like a volume control.

Another would be wiring tone pot to ground. There should be no ground connection from tone pot except through the cap.

 

[Artie]

Re: Tone pot acting like a volume control.

Another would be wiring tone pot to ground. There should be no ground connection from tone pot except through the cap.

Uhm. Sorry bro . . . but that's totally incorrect. Every tone control, within the context of a guitar, has two connections. "Hot" and ground. I always do my cap from volume pot to tone pot. Then, tone pot to ground. Somewhere, around here, I have my chart of the eight different ways to wire a tone control, that are all electrically identical. I'll try to find it, and post it, tomorrow.

 

[Artie]

Re: Tone pot acting like a volume control.

Let me elaborate. Unfortunately, we use the term "pot" to refer to a tone control. "Pot" is short for potentiometer. But that's an application of a mechanical device. The device is a variable resistor. If we wire it as a volume control, which is to say, a variable voltage divider, then it actually is a potentiometer. A device that varies the voltage, (potential difference), that is a potentiometer. But when we connect that same mechanical device as a tone control, we connect it as a rheostat. Totally different application. It's no longer a potentiometer. It's not a "pot". (Should we call it a Reo?)

The point being, a tone control has two connections. Hot and ground. Since it's a series connection, and we're dealing with an AC signal, it doesn't matter which comes first. Cap to ground, or rheostat to ground. Doesn't matter. This would make more sense with a diagram. But it's late. I'll post the pic, (diagram), tomorrow. Then, hopefully, this will be more clear.

I need a beer.

Artie

 

[freefrog]

Re: Tone pot acting like a volume control.

Uhm. Sorry bro . . . but that's totally incorrect. Every tone control, within the context of a guitar, has two connections. "Hot" and ground. I always do my cap from volume pot to tone pot. Then, tone pot to ground. Somewhere, around here, I have my chart of the eight different ways to wire a tone control, that are all electrically identical. I'll try to find it, and post it, tomorrow.

Artie,
I think Jacew was referring to a physical contact between the first leg of the cap (the one coming from the lug then going to the capacitor) and the grounded case of the pot.
In this case, the cap is shorted since its first leg becomes a mere jumper between lug and ground... and the tone control becomes a volume pot.
Pic below.



PS-the same problem will happen even with a properly mounted cap, if ever the lug itself touches the "ceiling" of the grounded cavity.

 

[Chistopher]

Re: Tone pot acting like a volume control.

But when we connect that same mechanical device as a tone control, we connect it as a rheostat. Totally different application. It's no longer a potentiometer. It's not a "pot". (Should we call it a Reo?)

If we did that, someone might go out and buy a rheostat.

 

[Jacew]

Re: Tone pot acting like a volume control.

Uhm. Sorry bro . . . but that's totally incorrect. Every tone control, within the context of a guitar, has two connections. "Hot" and ground. I always do my cap from volume pot to tone pot. Then, tone pot to ground. Somewhere, around here, I have my chart of the eight different ways to wire a tone control, that are all electrically identical. I'll try to find it, and post it, tomorrow.

What freefrog said.

Being strat guy I just assumed that cap is wired after the pot. Of course it doesn't matter which way they are wired, but there needs to be cap between ground and hot in any case.'

I think just calling it a potentiometer, or pot, is easier anyway. That's what the component itself is called everywhere.

 

[Artie]

Re: Tone pot acting like a volume control.

Well, I may have been feeling my oats last night. I do that sometimes.

Sorry.

Artie

BTW Chistopher, nice pic of a rheostat.