Photo 1 shows the 4PDT switching matrix design for the "up" position, which will put the pickups half out-of-phase.
Let's start with what we'll need to get out-of-phase or half out-of-phase sounds:
- You will need to engage at least two pickups to get such sounds. A single pickup played by itself will always sound the same, no matter if you play it in phase or out of phase (more about this later). The magic starts when you engage two (or more) pickups with one in phase and the other one out of phase or half out of phase.
- In general, you'll need one switch for each pickup you want to put out of phase. This can be only one switch, like on the middle pickup of a Stratocaster, to cover both in-between switching positions (bridge+middle and neck+middle), or three phasing switches, like on Brian May´s "Red Special," with one switch for each of the three pickups.
My design of a multi-phase switch that we'll cover today can be used to expand already existing out-of-phase switches in a guitar or to design a new wiring of your choice, integrating such a switch. With this switch, you'll be able to cover all three possible phasing options: in phase, out of phase, and half out of phase.
The magic starts when you engage two (or more) pickups with one in phase and the other one out of phase or half out of phase.
All you need for this mod is the switch, plus a capacitor and a resistor for the half out-of-phase option. So, let's start with the switch itself. For this mod you need a 4PDT on-on-on switch, which means a switch with three switching positions (up-middle-down) and a total of 12 lugs, arranged in four independent sections. Such switches are on the border of being exotic, but they're still available. Since every manufacturer uses a slightly different switching matrix for such switches, you'll need to get one with the same switching matrix I used, which is more or less the quasi-standard for it. It's possible to use 4PDT switches with a different switching matrix, but you'd have to adopt the wiring to it. I've provided three photos of the switching matrix and the switch design for each position. Photo 1 shows the "up" position, which will put the pickups half out-of-phase. Photo 2 shows the "middle" position, which will give you the full out-of-phase option. And Photo 3 shows the "down" position, which is just the normal in-phase operation.
Placing such physically large-sized switches on a pickguard or control plate can be a challenge, so you'll have to be creative. There is no way around such a switch when you want this mod because there are no existing push-pull or push-push pots with on-on-on switches. If you can find a 4P3T rotary switch, you can use it to substitute the switch by replacing one of the pots with it. There are also 4PDT slider switches available, but they're physically about the same size, and therefore, not a real alternative.
Photo 2 shows the 4PDT switching matrix design for the "middle" position, which will give you the full out-of-phase option.
Image courtesy of singlecoil.com
Here we go with the wiring of the switch, shown in Fig. 1. With the lever down you have the normal in-phase operation, with the lever up the pickup is half-out-of-phase, and in the middle position you have the full out-of-phase option.
Anyway, there you have it, all in one switch as shown in Fig. 1. On the left side of the switch, you see a capacitor in series with a resistor for the half out-of-phase option. A good average value is using a 0.01 uF capacitor with a 6.2k-ohm resistor in series as an additional serial attenuation of the system, preventing an impedance peak.
When looking at the switch, you'll notice that one switching stage is not populated at all. You might ask: Why don't we use a 3PDT switch for this if we only need three switching stages? This is because of the asymmetrical switching matrix of the 4PDT switches in the middle position (Photo 2) and there's no way around it. If the on-on-on switch had a completely symmetrical switching matrix, then three switching stages would be enough, but such switches aren't available today.
Photo 3 shows the 4PDT switching matrix design "down" position, which is just a normal in-phase option.
Image courtesy of singlecoil.com
In general, you add a controlled degree of reversed phase of the pickup when using the half out-of-phase option, which is great to mimic Stratocaster in-between "quack tones" on a Telecaster, like on the Jerry Donahue Tele models or with the Bill Lawrence Telecaster wiring.
Phase differences are measured in degrees. Totally in-phase sounds have either 0 or 360 degrees of difference, meaning none. Totally out-of-phase sounds have a 180-degree difference. So, half out of phase is either 90 or 270 degrees of difference. That's the reason why you can only achieve a fully out-of-phase effect when using two pickups together with one wired out-of-phase. (When both pickups are wired out of phase, they sound the same as both pickups in phase, because there are still 0 degrees of phase difference between them.) When a signal passes through a capacitor, the voltage leads the current by 90 degrees, so when a pickup's signal gets routed through a capacitor, it shifts the phase by 90 degrees—exactly half of 180 degrees—and therefore half out-of-phase ... in simple terms.
The cap connected to the switch is the phase-shifting cap mentioned above. A 0.01 uF cap is a great starting point, but you may try caps between 0.005 uF (5000 pF) and 0.022 uF. The smaller the cap, the sweeter the sound will be, but this really depends on your particular pickups. I recommend experimentation and fine-tuning to get as close as possible to a Strat's in-between tones.
As for the attenuation resistor, a 6.2k-ohm resistor works pretty well with the 0.01 uF cap and standard single-coil pickups. As a simple guideline, you can follow this rule by choosing and experimenting with this resistor: The higher the value, the more attenuation in the system, the smaller the impedance peak. A good starting point is the DCR of the pickup that's connected to the switch. For example, if your pickup measures a DCR of 6.8k ohms, you should start with a 6.8k-ohm resistor on the switch for a balanced sound and experiment from there. A good option is to use a small trim pot first so you can experiment until you find the value you like best. You can measure the trim pot and solder a fixed resistor with the measured value on the switch, or simply leave the trim pot where it is. A 10k or 15k trim pot is perfect for this.
That's it for this round. In honor of Fender's 75th Anniversary, next month we'll take a deeper look into Fender's history, busting some myths, misunderstandings, and urban legends, while celebrating the man behind the company that started it all: Mr. Clarence Leonidas Fender, or Leo Fender, as the world calls him.
Until then ... keep on modding!
Photo 1
To resume from the first part, please remember that the goal is to connect an individual part or piece in the circuit to ground, and the quality of a ground connection inside a passive circuit is not dominated by the gauge of the wire that's used. So, the more the merrier may look cool, but it's simply not necessary to overdo it here. Personally, I use a silver-plated, solid core AWG24 copper wire that looks nice and shiny and is also a joy to work with.
Let's start with version #1, the method that started it all: soldering the lug directly to the casing of the pot. This is the version Leo Fender used (remember: Leo didn't waste time on anything that wasn't necessary), but Gibson and all others used it as well. I like to call it the "cowboy version," or, for you Trekkies: This is the version James T. Kirk would have chosen when he would be into guitar-circuit soldering.
The handle of the cage is used to connect all three ground wires from the pickups individually, so it's easy to remove only one when you need to without adding any more heat to the case.
This is the most basic version and it's simply about bending the lug towards the casing of the pot and soldering both parts together as shown here in our example on a Stratocaster volume pot from 1965 (Photo 1). This sounds easy but it isn't. When you're not restoring a vintage guitar, I recommend using one of the other versions that follow. Depending on the pot, chances are good that you'll break the lug easily while attempting to make it touch the casing. This isn't the end of the world, but avoidable trouble.
Let's assume you managed to bend the lug towards the case without breaking it. You'll need a really hot soldering iron to connect both parts with each other, and soldering time will be a little bit longer than usual. The chance of overheating the pot is something to consider. With a good and quick soldering technique that comes with experience and the right tools, it's doable, but avoiding overheating is important to not kill your pot. If you're working on a vintage guitar, be very careful to not break the lug while bending it. Take care to clean both contact points and use a heatsink wherever possible. For more tips about soldering to pots, please read this column I wrote last year: "How to Install and Maintain Your Guitar's Pots."
Photo 2
Courtesy of singlecoil.com
All following versions are the "Gentleman versions," or, for the Trekkies out there: These are the versions Jean-Luc Picard would choose. Version #2 involves extending the ground wire. This is easy and neat to do when you're running a bare ground wire from pot to pot. Instead of soldering it directly to the case of the pot, run the wire though the lug of the pot you want to ground and solder it as shown here in a Stratocaster wiring example using a shielded output wire to the jack (Photo 2).
Photo 3
Courtesy of singlecoil.com
Version #3 is a kind of variation of version #2, using the grounded lug as the ground connection for the output jack, as shown here on a vintage-style Stratocaster wiring (Photo 3). Simply extend the ground wire for the output jack though the lug and solder it to the case and the lug, and you're done. I really like to use this version for a clean wiring, and as long as all pots are grounded this one works pretty awesome.
Version #4 is using a ground strap. When you're using a ground strap from pot to pot, you already must solder it to the case of the volume pot. Instead of heating up the case for a second time to connect the lug to ground, it's much more reasonable and easier to connect the lug to the ground strap. For this you have three choices:
1. Leave some slack on the ground strap so it touches the lug.
2. Bend the lug upwards so it touches the ground strap. Do not break it!
3. Solder a piece of wire to the lug and the other end to the ground strap.
Photo 4
Courtesy of singlecoil.com
In our example, shown in Photo 4, I used the slack method, so soldering was easy.
Photo 5
Courtesy of singlecoil.com
Now let's have a look at how to connect the ground wires of the pickups to ground, starting with the method Fender used right from the start on the Stratocaster: soldering all three wires side by side on the case (Photo 5).
Here you can clearly see: The lug is directly soldered to the case and the additional black wire you see is the ground wire from the output jack, so this case had to stand a lot of heat during the installation process. The advantage of this method is it's easy to change only one pickup if you need to by unsoldering only its individual ground wire. The disadvantage (besides the large amount of heat to the case) is that you need some practice to master this method because you must hold all three wires in place while soldering and usually need three hands for this (another one of those "alien tasks" in lutherie).
Photo 6
Courtesy of singlecoil.com
A really good alternative is to twist and solder all three ground wires together, so you only have one small soldering spot on the case (Photo 6). This is quick and easy to do, looks neat, and saves you some time, nerves, and exposed heat to the pot's case. You can also extend the twisted part to the lug you want to ground, similar to version #3 above, only the other way around. The disadvantage is that it's not so easy to change only one of the pickups if you need to. You'll have to unsolder all three ground wires, cut off the twisted part and pull out the wire you need.
Photo 7
Courtesy of Mark Foley/mfguitarproducts.com
In closing, I want to show you a really cool version that brings it all together that my friend Mark Foley, from MF Guitar Products in the U.K., is using.
Foley builds a kind of cage on the volume pots, connecting the lug with a piece of wire to another piece of wire (Photo 7). The intention and advantages are clear to see: Bending a lug downwards is much easier than upwards and the chance of breaking it is very minimal. Besides this, you only have two small soldering spots on the case that are quick and easy to do, saving a lot of heat on the case. So, what is the "handle" running across the case of the pot for? Is it only for connecting the wire coming from the lug? No, the best part is yet to come.
Photo 8
Courtesy of Mark Foley/mfguitarproducts.com
The handle of the cage is used to connect all three ground wires from the pickups individually, so it's easy to remove only one when you need to without adding any more heat to the case (Photo 8). It's also the perfect connection point for any other ground wires in the circuit, like the ground wire from the output jack, the string grounding wire coming from the tremolo claw, etc. And it's also a great guide for the hot wires from the pickups on their way to the pickup selector switch, so you don't need to use any additional tape, cable ties, or whatever else to bundle the wires. Is that a cool and clever solution, or what?
That's it for the topic of grounding. Next month we'll explore our next guitar mod, so stay tuned. Until then ... keep on modding!