In the previous article we looked at on-on switches, and on-off-on switches. There’s one more kind of toggle switch for us to look at.
The last type of DPDT switch we’re going to look at is the on-on-on switch. This is another three-position switch, and the connections it makes in the three positions are as follows:
You’ll see there are two types possible. It’s important when wiring one of these switches to be sure which type you’ve got. You can check this with a multimeter (I strongly recommend getting a multimeter if you’re going to be doing any guitar wiring at all – they’re cheap and extremely useful). In this article I’m going to use Type I, as it’s far more common. However, when reading diagrams on the internet it’s important to ensure that when an on-on-on switch is shown, you know what type it is, and how to adjust your wiring accordingly.
I’m going to show you two examples of wiring we can do with an on-on-on switch. The first is a series/split/parallel switch. This gives you a choice between a standard humbucker, a single coil, and the two coils wired in parallel – as if they were two separate single coils selected to run together on a single-coil guitar.
Here’s the wiring diagram:
Looks complicated? It’s not really. Firstly, the yellow line across the switch is a “jumper” – a short cable we use to connect two terminals on a switch. And in all switch positions, the green and black are grounded and the black goes to hot.
When the switch is in the “down” position, the red and white terminals will be connected to each other, through the jumper, and no other connections are changed. This gives us our normal series humbucking mode.
In the “middle” position, the red and white are still connected to each other through the jumper, but there is now also a connection from the white to ground. This is our normal way of splitting the humbucker to the slug coil.
Finally, in the “up” position, the red and white are no longer connected to each other. The red is connected to the hot output, and the white is connected to ground. This means that the path from ground to hot now splits in half, goes through both coils, and joins together again at the hot output. This means that both coils are wired in parallel. This gives a single-coil-like sound that is still hum-cancelling.
Another thing we can use an on-on-on switch for is to choose between three separate pickups, using only a mini toggle switch. To achieve that, we would wire the switch as follows:
Again we have a jumper on the switch. We take the hot outputs from three pickups A, B and C to the switch, and only one of them is ever connected to the output. In the “up” position, pickup C is connected, in the “middle” position it’s pickup B, and in the “down” position it’s pickup A.
You now know about the main types of switch used in guitar wiring, and have seen some examples of how we can use them. This gives us yet another tool we can use to achieve the combinations and sounds we dream up.
This video shows the difference in tone between series, split and parallel wiring:
Next time we’ll take a break from wiring and gain an understanding of how hum-cancelling works.