On a 425.......

[fireglo67]

with one pick-up, what does the switch do?

[jps]

it is a tone switch. Or it should be according to theory.

[tennis_nick]

with one pick-up, what does the switch do?

I think it acts like the switch on an Esquire, different capacitors and such altering the tone.

[sloop_john_b]

with one pick-up, what does the switch do?

This is the way I understand it - with the switch up, you get the full-on sound of the pickup. With the switch down, bass and output is decreased dramatically, which leads me to believe that it engages a bass cut capacitor.

[fireglo67]

But isn't there already a tone knob?

[tennis_nick]

But isn't there already a tone knob?

Re-Esquire

[jdogric12]

I'm not sure about the reissues, but I have a '63 900 (single pickup short scale) with V, T, and a 2-way switch. It's some kind of bass boost. Not quite a mud switch. I have a '67 900 with a 3-way: Tone knob in use, Equivalent of Tone at 10, Equivalent of Tone at 1 (mud).

Edit: late 50's early 60's these had a 3 way rotary knob instead of a bat switch.

[fireglo67]

So is it a 'useful' switch?

I guess most folks just leave it on the brightest setting?

[grazioso]

it is just bit of learning curve that is all, it is nice to go from dark tone to bright and back without rotation required.

[whojamfan]

I had a 425FG in the early 80s, and found the toggle to be quite usefull. It does a pretty good job of giving you 3 good tones, as well as the flipping the toggle thing that Townshend made so popular. Wish I still had that guitar.