Pickups Loading a Circuit

[andy]

Now, I don't want to sound like I know what this means, but I have heard it is an issue with multi-pickup circuits.

My issue is that I have a 3 pickup SG (see www.guitarnuts2.proboards45.com/index.cgi?board=music&action=display&thread=3434) with a slightly dodgy selector switch. I had planned to remove it altogether and have just three volumes and a master tone ...BUT... I have noticed that when the switch is in position 1 or 3 (bridge/middle or neck/middle) the tone of each pickup is clearer (more treble and mid-detail) than any selection in position 2 (all three). This setup obviously relies on the use of the volume knobs to select any pickup alone, but the sound still changes for a single pickup when the switch is moved. Could this be to do with the pickups loading the circuit as they are introduced by the switch, even with their volume down? Or are the all constantly 'in' the circuit as they are all physically attached anyway?

More's the point, if I got rid of the switch, and had just three volumes running to one master tone, running to one output, would the fact that there are more pickups affect the tone of each other one? Or do I just have a rubbish switch or poor quality circuit to be making these kinds of odd tone changes?

Cheers, Andy

[ChrisK]

In position 1, the bridge and middle are selected, or rather their volume pots are selected.

In position 3, the neck and middle are selected, or rather their volume pots are selected.

And, in position 2, the neck and middle and bridge are selected, or rather their volume pots are selected.


Their volume pots are selected!

In position 1 & 3, two pickups are driving two volume pots, unless one pickup is turned all the way down (reverse LP wiring one presumes) and the other is then driving two 500K pots (250K + amp input).

In position 2, three pickups are driving three volume pots, unless two pickups are turned all the way down (reverse LP wiring one presumes) and the other is then driving three 500K pots (167K + amp input).

[andy]

Thanks Chris, I see how that works.

So that must mean that losing the switch altogether is more likely to end up sounding like position 2 than 1 or 3. Correct? Or does the lack of a switch change the equation (I'm thinking pickup -> volume -> shared tone -> output)?

[ChrisK]

So that must mean that losing the switch altogether is more likely to end up sounding like position 2 than 1 or 3. Correct?

Yep, you get it.

Or does the lack of a switch change the equation

Don't second guess, you see things just fine.