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Tone Pot Issue - master luthier electricians needed - WY

Right now, I have a 6 string electric, 2 humbuckers that can split between single and dual coil, a set of switches to control them, 2 tone pots, one 'blender' pot and one volume pot.

The issue is with the tone pots: I get no change in tone until a certain point then the tone drops to mud. kinda like the tone just falls off a cliff. Here is the wiring:

Again, everything works except the tone simply cuts out at a certain point. The pots are 500K and the caps are .047uf. This is driving me NUTS. This diagram is based off Seymour Duncan: 2 Hums, 1 Vol, 2 tones, 3way switch diagram. The blender is taking the place of the 3 way and I included the SPDT O-F-O switches to control the single/dual tap. I have even grounded Lug 3 on the tone pots.

Any insights as to what might cause the tone pots not to work correctly? Would I want to put in a 100K resistor in with the tone cap like this (at the tone pots, not volume pots):

The above is a low-pass filter in essence.

-WY

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Permalink Reply by Josh Gayou (SmokehouseGuitars) on October 12, 2011 at 4:05pm

Okay, here is the section from one of my reference books copied here word for word:

A linear pot is usually marked with a B or Lin and will reach 50% of its total resistance at 50% of its total rotation. Humans do not perceive volume as a linear scale, however, so these pots sound like they are doing very little for the first three-quarters of their rotation. Audio taper pots are usually marked with an A or Audio and have a logarithmic scale of resistance that increases volume in accordance with human hearing.

Moreover, all of the wiring schematics that I base my designs on always use a B pot for volume and an A pot for tone.

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Permalink Reply by Ted Crocker on October 12, 2011 at 7:00pm

Try not grounding the 3rd lug on the tone pot. I hate blend pots, way more control with a 3 way switch and 2 volume pots. Infinitely more. In the hand drawn sketch the tone pots don't look wired right. Looking from the bottom it should look like this:

No ground on the 3rd lug and the cap from the middle lug to the back of the pot to ground. I use audio taper pots.

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Permalink Reply by Roosterman on October 12, 2011 at 10:18pm

Try using 2 A pots instead of an A and B pot Wes.

B pots are linear and and give the impression of nothing happening for most of the rotation.

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Permalink Reply by Wes "I'm Baaaaack" Yates on October 12, 2011 at 11:44pm

Right. Hmmmm. I think its a wiring issue rather than a pot issue.

-WY

Josh Gayou (SmokehouseGuitars) said:

Okay, here is the section from one of my reference books copied here word for word:

A linear pot is usually marked with a B or Lin and will reach 50% of its total resistance at 50% of its total rotation. Humans do not perceive volume as a linear scale, however, so these pots sound like they are doing very little for the first three-quarters of their rotation. Audio taper pots are usually marked with an A or Audio and have a logarithmic scale of resistance that increases volume in accordance with human hearing.

Moreover, all of the wiring schematics that I base my designs on always use a B pot for volume and an A pot for tone.

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Permalink Reply by Wes "I'm Baaaaack" Yates on October 12, 2011 at 11:48pm

Yup. Had it that way originally.

Ehhhh, well, a 3-way only has three selections per se -- neck/neck-bridge/bridge. The switches I have can control not only each pup, but if its single, off, or dual coil.I just can't find a good single switch to control each pup individually.

Now, what I REALLY need is a true blend pot.

Ted Crocker said:

Try not grounding the 3rd lug on the tone pot. I hate blend pots, way more control with a 3 way switch and 2 volume pots. Infinitely more. In the hand drawn sketch the tone pots don't look wired right. Looking from the bottom it should look like this:

No ground on the 3rd lug and the cap from the middle lug to the back of the pot to ground. I use audio taper pots.