Of course, today, Separate Rhythm & Lead Circuits, or heck the "poker chip" on a Les Paul does not mean much, but there is a lot of untapped potential in this wiring scheme, however, adding some traditional methods of adding humbuckers with multiple switching options, or wiring in an active circuit that has an effect on one or both circuits, can be a tricky endeavor if you don't understand how these circuits work.

STOCK JAGUAR/JAZZMASTER CIRCUITS

The Stock Jazzmaster circuit introduced in 1958 consists of a single double-pole,double throw slide switch,a nd the rest of the guitar revolves all around that switch. That switch is located on the bass-side horn above two little roller wheels for the rhythm circuit. The two components that are ALWAYS connected to it are the output jack hot post, and the hot-lead of the neck pickup.

When the slide switch is slid toward the bass side, the neck pickup is fed into a 1MEG ohm Linear potentiometer for volume, and a 50K Ohm Linear potentiometer for "tone", giving it a murky and dark guitar tone suitable for playing chords and smoothing out the highs. This circuit, while the pot spacing is different, the wiring is almost identical on both guitars. The audio is then fed out of the pots and back to the output jack en-route to amplifier.

When the slide switch is put toward the "treble side" of the guitar, the lead circuit becomes active. The neck pickup is then fed into either a 3-way Gibson-style toggle switch (Jazzmaster), or it's own individual SPST slide switch (Jaguar). The Bridge pickup wires straight into the toggle as well (Jazzmaster), or it's own SPST toggle (Jaguar), with the output signal from each sharing a common wire with a third switch on a Jaguar, the "Strangle Switch". This then feeds the signal down into a pair of 1MEG pots, one Logarithmic and one Linear (Jazzmaster), or 2 Logarithmic (Jaguar) - these control volume and tone just like any other electirc guitar. THen the signal is fed out of the circuit back to the output jack to the amplifier.

Now let's discuss what the "Strangle Switch" actually is, because this is the #1 thing people mess up when describing the Fender Jaguar's complex tone circuitry. The Strangle switch is really simple - it's a .01uf capacitor that runs the hot-lead signal through it when it's on. It's not a phase change, it's not a high cut or a series-parallel switch - it's a BASS CUT, or what we call a "Hi-Pass Filter" - which let's treble frequencies come over. And it's effect as "Strangle Switch" is really quite subtle, sometimes VERY subtle depending on the amplifier. It also can be quite useful, especially for things like Funk, or a clean part of a song, or somewhere where you want more of a "sharper" punctuation. It also only affects the Lead Circuit.

It's not hard to see what Fender was going for here with this circuit. Basically, you preset your rhythm sound with the rollers, and your lead sound with the lead circuit, and then, you just use the one switch to toggle back and fourth between your "presets", and that's about it.

The thing you have to understand is these guitars have 2 "GLOBAL" Constants - to use programming language terms - these are the output jack, and the neck pickup. Everything else is unique to a specific circuit.

Anything you carry out on the bridge pickup will only affect the lead circuit (assuming you're keeping the wiring stock otherwise). So say, if you had a coil split on a bridge humbucker on a Jazzmaster - you don't need to really change much of the wiring - the pickup goes into the lead circuit selector just like a regular one circuit guitar, and thusly, can be pretty much treated as such.

However, the Neck pickup - which is also my faovirte one to put all the various switching options on anyway because I tend to pick bridge pickups that I like the sound of straight-up - presents a special challenge.

You will need to do ALL tonal mods BEFORE the Rhythm/Lead Circuit Switch. So that means, if you are doing phase reverse, the hot and ground leads need to go to that phase switch BEFORE the switch even goes to the rhythm/lead selector switch - and then the ground goes to ground, and the hot goes to the 2-way slide switch on the upper horn.

Things like coil splits are going to be independant of the switching scheme for the most part, however, this does mean that you will need to keep in mind that when you change from Rhythm to Lead, and if you want to change to a Single coil on the lead circuit and a humbucker on the rhythm circuit - you'll need to change TWO switches now instead of one to carry that change out.

Now, let's talk about another bit of wiring mods. It is possible to put BOTH pickups on the rhythm circuit by instead - by instead wiring both pickups to the toggle/slide switches, and then wiring the output of said switches to the rhythm/lead switch. This expands on Freddie Tavarez idea of the preset circuit, giving more tonal options in the rhythm side. This is something I have yet to experiment with.

Another common reuse of the Rhythm circuit switching, for those who don't like/use it, would employ this, and instead, uses the roller wheels and rhythm circuit area as a enclosure for various devices you could add, and allows you to switch them in or out of the circuit. This could include putting an entire pedal in the guitar. Maybe you want a fuzz built in, or a built in treble booster. Maybe even just a 2 band active EQ, or a preamp. All you'd have to do is feed the output of the lead circuit into the switch, then on the other side have a wire guiding the output from the lead circuit into whatever device you installed, and then the second wire that connects to the output would go to the output jack with the switch up. Basically, it's turning the rhythm circuit into a send-return for onboard devices instead, and you could use the two roller wheels to control whatever device you installed.

So when Freddie Tavarez came up with the Rhythm/Lead circuit concept, the whole idea was to make 2 volume presets on the same guitar for the purpose of rhythm and lead guitar tone. In the 1960's, there was no "free Way" selector, and of course, even Strats were using a 3-Way switch, not a Five Way (that did not come fact'ry till' 1979). My idea is, retain the same two circuits, and instead, do the circuit switch using the Free-Way switch, not the DPDT Slider on the upper horn. So with the switch in the down three positions, you get neck, neck+bridge, and bridge alone, on the brighter lead circuit,a nd then in the upper 3 positions you get neck, neck+bridge, and bridge alone on the rhythm circuit. That economizes the player's switching options down to ONE switch that does it all. And on top of it, on a stock Jaguar (with a Cobain Control Plate) or Jazzmaster - you can use that DPDT switch for something else - like maybe the phase of one of the pickups, or even as a blower/boost switch for solos! Plus it adds at least 2 more sounds to the guitar's tonal pallette.

And now, on a stock Jaguar or JAzzmaster with this scheme enabled - you'd have one more switch to play with - a DPDT slide switch. You could change the phase of one of the pickups allowing out of phase options, you could make a series/parallel switch out of it. Another idea would be to wire in some kind of preset preamp for a solo boost or a preset effect unit you use often embedded in the guitar somewhere. The possibilities are endless. You could even just replace it with a pushbutton for a kill switch - or even relocate the freeway up there, and put a kill switch where the lead toggle is. Quite a few ideas.