Product spotlight - The CTS Push/Pull pot & coil split wiring
Push/Pull pots have been incredibly popular for guitarists for many years as they can help with alternative switching and tonal options without any real changes to the aesthetics of your guitar or the need to drill additional holes. They're regular pots but with an on/on DPDT switch mounted to the back casing allowing for some interesting wiring styles to be achieved.

If your control cavity allows (in regards to space available) then the CTS PCB Push/Pull pot is a superb, high quality option for your alternative switching needs. But does appear a little different to other equivalent push/pull pots on the market so I though it would be good to do a little spotlight on it and hopefully help explain those differences.

Push/Pull & Push/Push Guitar pots

The traditional DPDT push/pull pot
Perhaps the most common push/pull pots on the market are the ones shown in the photo above. These are made with mini sized pots, which do have their advantages in terms of the minimal space/footprint taken up within the control cavity for example but can often lack the overall quality of a full sized CTS pot. Whether that's simply due tolerances, rotation feel or construction/longevity. This style of pot essentially features a regular DPDT switch mounted to the back casing of the pot and is operated via a push/pull or push/push pot shaft. The switch lugs, although small, are easily accessible and simple to wire up.

CTS Push/Pull DPDT PCB pot

About the CTS Push/Pull pot
CTS produce a very high quality version of the push/pull pot which looks quite a lot different to these conventional versions mentioned above. You'll notice the overall size difference perhaps initially. That's because these are a full sized CTS pot instead of a mini sized pot and these ones in particular feature very similar specs to the high quality CTS standard pots I stock like the 'TVT' or '450' series, with brass pot shafts & +/-10% tolerance value. Which is one of the main reasons I really like these!
But instead of a traditional looking DPDT switch on the back like it's mini-pot counterpart, this has a large black casing with a PCB board mounted alongside the pot lugs. Here you have little numbered eyelets for your switch connections but they work very much in the same way once you have familiarised yourself with them. One little handy thing to note though are the slightly more traditionally laid out PCB lugs that look much more like the convension push/pull switch lugs. These are the ones on the PCB shown furthest away from the pot shaft on the photo below. These can be helpful if you're working with a wiring diagram that shows a traditional push/pull pot but you want to use this higher quality CTS push/pull instead for example, but also as the eyelets are numbered, things are pretty easy to follow here though once you get over the initial visual differences.

CTS Push/Pull Pot wiring

What do the numbered eyelets refer to?
Much like the standard DPDT Push/Pull, you have two 'common' eyelets, marked as C1 & C2. Those would be the same as the central two lugs on the regular DPDT push/pull. Alongside those are numbered eyelets 1 & 3, which correspond to the switch in it's pulled up location (the lugs that would be closest to the pot on a regular push/pull), and numbered eyelets 2 & 4 (the lugs that would be furthers away from the pot on a regular push/pull) which correspond to the switch in it's pushed down location. If you've ever wired up a regular push/pull pot then reading that will already likely start to feel more familiar. 

470k resistor mod

Switch purposes
You could use a push/pull pot for so many purposes, phase switching, multiple tone capacitor options, coil tapping etc. But one of the most popular uses for a push/pull is to achieve coil splitting for humbucker pickups so let's start off by looking at how you would wire the switch for this function. When you're 'splitting' a humbucker, you're basically putting the signal from one of the humbucker coils to ground, resulting in a 'single coil' so to speak.
Up until learning a little more about guitar wiring over the years, I'll be honest, I really didn't like the coil split sound. I couldn't help but feel that a humbucker rarely ever sounds as good split as a true single coil would. Often sounding thin, brittle or too bright for example. This, as with anything guitar tone related, is of course subjective, the examples I tried may simply have been pickup models that don't lend themselves well to coil split, or component choices that don't do it justice. So I'm not totally closed minded on the subject, just skeptical of it's benefits shall we say lol. Some may like it as is and find the position very useful so the best way to find out is to try it for yourself rather than take people's word for it on the internet! (Even I admit that, given the irony of writing a post about it!! Personal preference is best when it comes to guitar sounds).
Now I am going to throw a quick suggestion in here and that is to ultilise the trusty 470k resistor mod like on my popular Humbucker/Single coil Telecaster harnesses for example so let's have a look at what I mean..

4 conductor pickup wires

Coil splitting with the 470k resistor mod
There's a few reasons as to why coil splitting can result in a thin/brittle sounding single coil tone but one 'solution' that can very easily assist with it is what pot value the pickup 'sees' when it is split. A humbucker is most commonly paired with 500k pots. Due to it's design, humbuckers are a somewhat naturally darker sounding pickup so to sound it's best and allow more treble frequencies through resulting in a clearer tone and improved dynamics if you will, 500k pots are an optimal choice and most commonly used. But when you split the humbucker, essentially making it a single coil pickup so to speak, the single coil continues to have it's signal pass through a 500k pot which can result in a thinner or brighter tone for that application. But with using a 470k resistor, when you send one coil signal to ground via the resistor wired in parallel, that signal will 'see' closer to it's preferred 250k pot rating. Helping tame those highs and hopefully result in a more balanced split coil tone.

Coil Splitting a humbucker with CTS Push/Pull pots

You may be wondering why the numbers here don't make sense though, well firstly 500k resistors aren't commonly produced so 470k resistors are much more readily available and get you as close as possible to the desired value. But why would you not just use a 250k resistor? Well that's because it is wired in parallel, and this is how you calculate resistors wired in parallel - 

Resistance 1 (let's say the pot) x Resistance 2 (the resistor) divided by resistance 1 (pot) + resistance 2 (resistor) = Final value

500k (pot) x 470k (resistor) divided by 500k (pot) + 470k (resistor) = 242k

So to summarise, instead of putting one coil to ground as normal, do so via a 470k resistor so the single coil 'sees' 242k pot value and therefore closer to it's optimal/preferred value for a more balanced single coil tone. There are other resistor values you could use too and some manufacturers even ultilise a partial coil 'tap' instead of a full coil split, meaning you don't put a full coil's signal to ground, but instead only some of it resulting in a chunkier 'split' sound. I might touch on that in another article to save going too off topic here (granted, I already have I know, thanks for sticking with it lol).

Wiring a CTS Push/Pull Pot for coil split

Wiring it up
Here we go then! For ease of translation I have simply decided to refer to Seymour Duncan's 4 conductor colour coding. They're perhaps the most widely used wiring colour codes and the easiest to find conversion diagrams so figured it would be simplest to use their colour coding for this diagram.

You could use either the C1 or C2 eyelets here, for the sake of this example I have shown it on the C1 side. It may simply come down to convenience within the control cavity to which side you use, you might have easier access on one side of the pot to the other within the cavity, so I'll keep the diagram simple and show it via C1 but will explain which number eyelets you would use if using C2. If you're coil splitting two humbuckers via one push/pull, then you may choose to make things a little less claustrophobic and use both sides of the switch instead of trying to fit multiple wires into one eyelet. Plenty of options!

Finally getting stuck in
First of all, I would prepare my ground, or on this example the 470k resistor to ground but if you don't want to use the resistor, just use a length of plain wire instead. This would be located in the number 1 (if using C1 side) or number 3 (if using C2 side) eyelet with the other end of the wire or resistor soldered to the pot's metal casing. There isn't much real estate of metal pot casing on these, as the plastic switch casing covers the majority of the pot, but just use the side of the pot casing here.
Why the number 1 or 3 eyelets? Well when the push/pull pot is pulled upwards, those eyelets would be selected via the PCB causing the signal from the common eyelets to find it's way to ground and be removed from the live signal.
Which leads me now to the common connections, and the C1 eyelet in this example. Here you want to attach your pickups' 'series link' wires which are the north coil finish wire and the south coil finish wire. For Seymour Duncan, they are the red and white wires, which are put together and soldered to the C1 eyelet (or the C2 if using that side). 
Now simply solder the usual pickup's ground wires to ground, this could be on the metal pot casing, or another point of ground on your wiring harness. Again, for Seymour Duncan these are the Green and bare/silver wires. Then finally, you will have your main pickup 'hot' wire, which will need to be connected to the relevant connection on your harness depending on which position you intend on installing the push/pull pot, IE Volume or Tone. Usually one of the pot lugs or your pickup selector. There are so many guitar models and wiring styles so couldn't really go into full detail on this without showing loads of diagrams, so have just concentrated on how to wire the actual DPDT switch in this article.

CTS Push/Pull coil split wiring

& you're ready! That's the DPDT PCB switch connections made, and ready to achieve coil split tones. I hope the 470k resistor mod idea works for you too, it certainly makes me enjoy the split coil tone more. I recently released an Ibanez RG/Jem style HSH wiring harness that splits the coils in positions 2 & 4 on the 5 way switch, and ultilised the 470k resistor mod there too and was really impressed with the results. Achieved a great sounding single coil tone, or certainly as close as possible.

There are so many ways you could wire up a push/pull pot, but seeing as coil splitting is the most popular use I thought it would be good to highlight this first and maybe future articles look at alternative options. But I hope you enjoyed this read and found it helpful! Thanks for reading.

Want to order a CTS Push/Pull pot? I stock them here at James' Home of Tone and they can be found HERE

James

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