Tone control value help

Hi,

This is not tele centric.
Recently I bought one of the Gibson Melody Maker SGs. Equipped with a single humbucker and a volume pot, no tone pot. Without modification with a router, there is no way to put in a seperate tone pot. My thought was to change the volume control to a tone control.

I found this diagram:

http://i280.photobucket.com/albums/kk163/pchilson/Single_Tone_Wiring.jpg

I am now running with wide open volume (this is ok) and this tone control.
I used a 500k CTS linear pot that I had on hand, an .047 cap and a 500k resistor from the pickup input to ground to maintain the volume a 500k volume pot would. This is schematically working fine. However the tone rolloff occurs mainly at about 4 down to 0. That, I guess is ok as well. The problem lies in the amount of rolloff at the end just decends into mudville.

I'm thinking I should maybe try the 300k audio pot that was in the guitar for the volume control, ground a 300k resistor from the input and then possibly a .02 cap but I'm guessing at values here.

Its somewhat tedious to do the trial and error swapping so I thought I'd get some input from the membership.

The pickup is a Gibson 491T which is a ceramic and quite hot. Clean it is quite high mids and fairly bright. It sounds very good clean. When you kick in the overdrive/distortion it goes into this brash sound cause you can't roll off anywhere near enough of the highend with a volume pot alone. Hence the experiment with the swap from volume to tone.

A pickup change may be in order but I want to first control the rolloff and then I can evaluate that. If I can get acceptable results from this experiment then I will do the routing and install a dual concentric pot providing both volume and tone in one control location.

What values would you guys suggest for pot, cap and resistor? Audio or linear taper?

Thanks

The value of the pot won't change the muddiness when the tone is rolled all the way down, since the pot is zero ohms to the cap at that point. It will change the taper slightly, which might work out for you. Try a smaller cap (maybe .022 uF) for less mud. Make sure you're using an audio taper pot, a linear will often make the tone control ineffective till you have it most of the way down.

I'd go with the concentric volume/tone pots that will mount in your single hole, this way you could have both controls without hacking your guitar...

http://www.guitarpartsresource.com/electrical_concentricpots.htm

What's the resistor for?
Otherwise, here's my advice: First, always use audio taper for a tone control.
Cap value, I'd suggest 15 to 22nf.
Pot value, 250k should be fine, and I would also modify it to be no load (easy to do, I like the nail varnish method best).

But are you sure you want to lose the volume control? With a push pull pot you could add a fixed bassy sound, with concentric pots you'd have tone and volume, though it would be a bit fiddly, and finally you could maybe drill a second hole, no?

I'd go with the concentric volume/tone pots that will mount in your single hole, this way you could have both controls without hacking your guitar...

http://www.guitarpartsresource.com/electrical_concentricpots.htm

In order to use a concentric I will need to rout wood out of the bottom of the control cavity. There is not enough depth for a stacked pot as is.

http://i280.photobucket.com/albums/kk163/pchilson/Gibson_Melody_Maker_SG/1.jpg

http://i280.photobucket.com/albums/kk163/pchilson/Gibson_Melody_Maker_SG/2.jpg

What's the resistor for?

Otherwise, here's my advice: First, always use audio taper for a tone control.
Cap value, I'd suggest 15 to 22nf.
Pot value, 250k should be fine, and I would also modify it to be no load (easy to do, I like the nail varnish method best).

But are you sure you want to lose the volume control? With a push pull pot you could add a fixed bassy sound, with concentric pots you'd have tone and volume, though it would be a bit fiddly, and finally you could maybe drill a second hole, no?

My understanding is you add the resistor to create the resistance that a volume pot would have placed.

In order to use a concentric I will need to rout wood out of the bottom of the control cavity. There is not enough depth for a stacked pot as is.

My understanding is you add the resistor to create the resistance that a volume pot would have placed.

Yeah, I looked at the diagram again after posting and noticed that :-).

I'm going to swap out what I've got in there now with the original 300k audio pot, 300k resistor and a .022 cap and see if that is more in line with what I'm looking for.

The concept works I just need to nail down the values.

Thanks

The 300k audio pot measured out to 321k. I use a 320k resistor to ground from the input. I used an .022 cap from center lug to ground.

This combination has given a wider range to the tone sweep and has now made the guitar useable with overdriven tones.

Now to spend some time with it and see what I think about the pickup.