Tone knob wiring

[jeff]

As far as noise is concerned is there a difference between between wireing the cap to the hot and the pot to ground VS the pot to hot and the cap to ground? I realize that they are in series and either way won't affect the function of the tone knob but say the tone is full up. You have 500 resistance that's in a shielded pot attached to the hot and an unsheilded cap attached to ground. Isn't the cap more prone to pickup noise and therefore it's better to have it wired to ground than the hot of the jack?

[G._Hoffman]

As far as noise is concerned is there a difference between between wireing the cap to the hot and the pot to ground VS the pot to hot and the cap to ground? I realize that they are in series and either way won't affect the function of the tone knob but say the tone is full up. You have 500 resistance that's in a shielded pot attached to the hot and an unsheilded cap attached to ground. Isn't the cap more prone to pickup noise and therefore it's better to have it wired to ground than the hot of the jack?

In my experience, no, and as I understand the theory, no.  So, I THINK that should just mean, no.  I'm sure PRR will be along to explain why I'm wrong at some point, though.


Gabriel

[Willabe]

I'm sure PRR will be along to explain why I'm wrong at some point, though.

Yeah well, as Joe Walsh sang, "Join the Club". I love that song.       


                 Brad      

[HotBluePlates]

In my experience, no, and as I understand the theory, no.  So, I THINK that should just mean, no.  I'm sure PRR will be along to explain why I'm wrong at some point, though.

Theory is almost always based on experience, or modified/verified by experience. So I doubt PRR will say you're wrong.

Look at the attached diagram. It is a single pickup, with a tone circuit. I've ignored the pickup switch, showing just the complete circuit for the selected pickup.

Where's the ground? Where's hot? I've omitted any ground symbol, and connected the points that might have a ground symbol with a "wire" which is exactly what happens in the physical circuit.

Ground is just a reference point, not a magic black hole where noise disappears. You could choose to use a different point in the circuit (derived from the word "circle") as your reference. Would it make any difference in the possible noise where you placed your reference?

The way shielding works on an unbalanced circuit is that the shield, which is part of the signal-carrying circuit, is connected to your reference. The hope is that any noise induced in the hot conductor also gets induced in the reference, so both are altered the same way. Since there is (hopefully) no difference between the two except for the desired signal, there is no noise.

It's like you and a friend standing on a boat. If the waves cause the boat to bob up and down, you might notice when you look at the water or the shore. But if your only reference was the boat and your friend, you don't notice. You're both bobbling at the same time by the same amount.

[jeff]

I guess what got me thinking about this was reading the post about how there is a noisey way and a less noisey way to hook up a coupling cap in as far as inner foil outer foil. I don't know if tone caps are the same but it seems to me in a cap is likely to pickup noise, there would be a difference between hanging it off the tip or sleeve of the jack. The test for inner outer foil described hooking a cap to the hot of a guitar cord and touching the cap itself or placing it next to an AC source(lamp cord that's on). One way would be noisier than the other so to me that sounds like caps pick up noise/interferance.
I'm guessing though if you connected it to the ground of the guitar cord and touched it or put it next to an AC source, it wouldn't be as noisy as when it was connected to the hot/tip. If the noisy part(the cap) is connected to the hot with 500k to ground wouldn't it be more noisy than if the noisy part was connected to ground(and you) with 500K to the hot?
 Just as if your jack was reversed, it is more noisy when you touch the strings and are touching the hot then when it's wired right and you're touching ground???

[HotBluePlates]

I guess what got me thinking about this was reading the post about how there is a noisey way and a less noisey way to hook up a coupling cap in as far as inner foil outer foil.

This assumes the cap has an "outer foil" (or plate), which sometimes they don't.

When considering the orientation of an outer foil, the cap is always oriented so the outer foil is connected to the path with the lowest impedance to ground. The thought process is any external noise induced into the cap is shunted via the outer foil to the reference (ground). The outer foil is being used in a similar way as the shield of a guitar cable.

But honestly, if you have noise in your guitar, 90% of the time it's because you're using single-coil pickups (like me). You can minimize the noise by moving away from noise sources. The other 10% of the time, you are too close to a powerful source of radiated noise, like video CRT monitors, air compressors (or other motors), etc. You minimize that noise by moving away from it.

True, you can orient the guitar so the noise is minimized, somewhat like properly orienting power and output transformers.

I tried all the gimmicks way back, but you either want to play humbuckers (or other noiseless pickups), or you don't. And pickup noise dominates unless you have a major wiring error.