Jazzmaster
Oh how I love Jazzmasters! With all the funky switching and extra knobs, most people don’t even know what they’re all for. So a quick primer for the uninitiated: on the passenger side you’ve got two knobs that say volume and tone, and a toggle switch. The switch is your pickup selector. when it’s to the left, the left (neck) pickup is on, when it’s in the middle, both pups are on, and when it’s to the right–you guessed it–the bridge pickup is on. The volume and tone controls are both master controls, which means that they affect both pickups, instead of independently affecting each pickup like a Les Paul. That sure seems like all you’d need for a guitar to work, right? Then what in the world are those driver’s side controls for?
It’s best to think of them as working together as a “solo” switch. What happens is this: when the switch is down, the guitar works just as I already described, with the passenger side controls doing all the tone shaping and pickup selecting, but when the switch is up, no matter what those lower controls are doing, you’ll have just the neck pickup on, with the two finger knobs controlling the volume and tone. It bypasses the lower controls and just uses the upper controls. But why? Couldn’t you just select the neck pickup with the bottom switch and have essentially the same thing? Yes you could! But there is a subtle difference. The upper and lower tone knobs use different value capacitors, which makes their tonal shaping a little bit different.
The main advantage here is to be able to set two distinctly different tones and volumes and be able to switch between them with a single control–that also happens to be located in a pretty convenient place, accessible even while you’re using the tremolo! What a design! If only Fender had designed a halfway decent bridge for these things, no one would need to buy another guitar ever again. Mastery definitely solved the bridge problem, but that’s for another post!
Ok, why are we looking at the guts of this glorious beast? because, as you can see, there are a couple problems with the unique design. The biggest one is that the signal (white wire) coming out of the pickups has to go up and down and all over the place multiple times before it finally gets to the output jack. This is a bummer because unshielded signal wire is very susceptible to interference from nearby electrical sources, like fluorescent lighting, TV or computer screens, box fans, WiFi, you name it. In our ever more electrically connected society, guitars are the unfortunate recipients of all kinds of noise from a variety of ambient fields. And this Jazzmaster was no exception. With some of the longest unshielded signal runs I’ve seen in a while, it made so much noise! Good thing there’s a solution. (also, for any of you nerds out there, notice that the output jack isn’t connected to ground. Another culprit in the generation of loud noises!)
That was quick! Now all the signal runs are shielded, there are no ground loops (and all the grounds are connected), and this puppy should be dead silent. I plugged it in to find out, and aside from 60Hz mains hum, which you can’t avoid (without some serious intervention) with single coil pickups, this guitar is as quiet as it’s ever going to be! Some of you may have noticed the treble bleed circuit on the master volume too. I like to leave mods like this easy to change/uninstall/reuse, hence the longer leads!
And just for fun, here’s some detail of the driver’s side solo controls in process. Thanks for reading! See you next week!