Need help understanding an RC high-pass filter

[McCreed]

Please be gentle and explain things as if you were talking to a six-year-old...

With my recent experience with a bass cut circuit with humbuckers, I've also been looking into simple high-pass filters.

I have used a passive RC filter before on neck humbuckers before but my understanding of how it works is rudimentary at best. My application is a parallel capacitor and resistor used in series with the pickup output.

I have experimented with the capacitor values and know on a very basic level that the lower the cap value, the more high frequencies will pass (or low frequencies filtered out).

What I would like help with is the role of the resistor in this application.
In very simple terms (remember I'm a six-year-old) what will increasing or decreasing the resistor value do to the operation of the circuit, and how will it effect the tone?

I've read something about "cut-off threshold" or something, but when I read that stuff, my vision gets blurry and my brain misfires...

Let me know if you need more info from me ie: pot/cap/resistor values etc.

[Cliff Rogers]

http://www.learningaboutelectronics....calculator.php

[Cliff Rogers]

If you play with it a bit you will see that the higher the value of the resistor, the lower the cutoff point and the lower the value of the resistor the higher the cutoff point.
If the resistor value is too high or infinite (not there) the cutoff point is so low you won’t hear any change at all.
If the resistor value is too low or zero, all the audible signal will be cut off.

[McCreed]

Thanks Cliff. I did come across that same site and calculator during my quest. (also added it to my bookmarks)

I can see what you mean about the changing values and how they change the outcome, but I'm still trying to wrap my head around how those numbers translate to real world sound and what my ears will hear.

Right now I'm using a .0068uf cap in parallel with a 500k Ω resistor. I've settled on that for today. I'm braindead now...

[Cliff Rogers]

Those values won’t make a lot of difference.

[Cliff Rogers]

The best trick is to have a couple of leads with alligator clips on them hanging out of the guitar or rig up a special guitar lead with the clips on it and try several different values and pick something to your taste.

[McCreed]

Those values won’t make a lot of difference.

Actually, they do. Subtle, yes, but noticeable and effective.

edit to add: The intent is just to brighten up the neck humbucker. It is often referred to as the "de-mud mod".

The best trick is to have a couple of leads with alligator clips on them hanging out of the guitar...

Yep. That's what I've been doing... and another reason why my brain hurts...

[Cliff Rogers]

Why do you have a 500K resistor in parallel with the capacitor?
What is the value of your volume pot?
The high pass filter is formed by the capacitor in line and the resistor going to ground, in this case, the volume pot.
All the resistor in parallel is doing is bypassing some of the signal around the capacitor therefore bypassing the high pass filter.

[Cliff Rogers]

Other ways to help ‘de-mud’ a humbucker are to reduce the height of the pickup, particularly the bass side, and you can just turn the mids up a bit on the EQ on the amp.

[McCreed]

Why do you have a 500K resistor in parallel with the capacitor?
What is the value of your volume pot?

I’m using 500k pots, and with a 4 conductor humbucker, the parallel RC is in series with the north and south coils.
With my limited understanding of electronic principles, I can’t tell you why what goes where, but I have followed schematics that show this configuration and placement.

I’ll post the drawing later. I’m away from my computer atm.