Guitar Wiring 102

Posted on by Richard Irons

Last week we got to the point where we had a guitar with one pickup and no controls. This week we’ll be taking more steps towards a full understanding of guitar wiring.

Cut That Out!

Assuming we don’t want to stop there, the simplest next step would be to add a ‘kill switch.’ This is a switch that silences the guitar in one position and allows the signal through in the other. You might think that we can simply add a mini-toggle switch in the hot wire to cut the output from the pickup, like so:

Pickup with simple toggle switch

However, when we use this switch to cut the signal, this scheme would actually cause the same noise we hear when we have a cable plugged into the amp but no guitar. We’re not ensuring that the two contacts are at equal voltage.

Instead, we need a switch that still completes the circuit, but cuts the pickup out of the equation, like this:

Pickup with working killswitch

With this switch, in the ‘on’ position, the hot jack contact is connected to the output of the pickup. In the ‘off’ position, it’s connected straight to ground (while the hot output from the pickup isn’t connected to anything at all). Now we have a kill switch that truly silences the guitar when engaged.

Turn It Up

A kill switch is OK, but even more useful is a volume control. A volume control uses a potentiometer, which is the component that lives behind the knobs on a guitar. This is what it looks like:

potentiometer

As you can see, there are three contacts on the pot. The outer two are connected to either end of a resistive strip, and the middle one is connected to a ‘wiper’ that moves across the strip as the knob is turned. By connecting our hot signal to the leftmost contact, and the rightmost contact to ground, we can give the middle contact a controllable ‘choice’ between being connected completely to the hot output, completely to ground, or anywhere in between. By connecting this middle contact to the jack, as in this diagram, we have implemented a volume control.

Pickup with volume control

In this diagram you can see that I’ve moved the ground connection from the pickup to the back of the volume control, and connected the ground connection to the same place as well as the volume’s third lug. It’s standard in guitar wiring that the ground wires are always connected to ground, for simplicity’s sake and to ensure that metal parts are grounded. It’s also fairly standard that the back of the volume pot is used as a grounding point for all wires to be grounded. There are pros, cons and exceptions, but a discussion of those is beyond the scope of this post.

Tone It Down

The last thing we’re going to look at in this article is adding a tone control. A tone control works differently to a volume control. It uses a pot and a capacitor together to ‘bleed’ the treble frequencies in the signal to ground. This works because putting a capacitor on a hot wire only allows treble frequencies to the other side. Once those treble frequencies are present on both hot and ground, the voltage difference is eliminated and the treble disappears from the audible output.

To attach a tone control to the circuit, we connect the input to the volume control (our hot signal from the pickup) to a second pot, at one end of the resistive strip. Then we connect a capacitor between the wiper contact of the pot and ground (for which we’ll use the pot casing). The other contact on the pot is unused, because we’re using it as a variable resistor in this instance, rather than as a voltage divider. Turning the pot down allows more signal to reach the capacitor, where the treble frequencies then leak through and are grounded. This is how it looks:

Pickup with volume and tone controls

That’s the last thing I’m going to explain in this post. We now have a guitar circuit with one pickup, and a master volume and tone control. That’s the exact circuit used in the prototype Fender Esquire.

In the next post in this series we’ll go into multiple pickups and switching. If you have any questions so far then please do post them in the comments, and I’ll do my best to answer them as quickly as I can.

Written on June 27, 2012, by Richard Irons

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Comments (33)

  • Richard Irons 6 years ago

    Looking forward to your next post I have an old Les Paul type gutiar in my basement that needs rewired

    • Richard Irons 6 years ago

      Glad you’re enjoying the series. The next article deals with pickup switching, to the point where you can understand how a standard Tele is wired – and then the one after that will bring you up to speed with the standard wiring for both a Strat and a Les Paul.

  • Richard Irons 6 years ago

    tnx! i’m interesting about HSH with 5-way switch, 1 vol and 1 tone control

  • Richard Irons 6 years ago

    I have a Kramer 300st which im messing with. Just recently added a Zebra Humbucker and a couple of SSL-5’s. The guitar has 1 Volume and 2 Tone pots with a 5-way switch and 1 Coil Tap mini. I would like to add a Concentric Pot for the Volume Pot so I could have 1 Volume and 1 Tone for both Single Coils together and 1 Volume and 1 Tone for the Humbucker. I have the original 300ST 5-way which has 3 legs on one side for each pickup, 3 legs on the other side used to send the signal to 1 of the 2 tone pots, and 1 leg in the middle to send the selected pickup signal to the Volume Pot then to the output Jack. If I use the Les Paul schematic and send the 2 single coil pickups to the Volume Pot first I will lose switchability between the two singles. I would like to keep switchability between all the pickups but I dont think ill be able to without buying 3 Concentric Pots (using each pot as a Volume and Tone) and designating each pot for a different pickup. The original Switch has no more output legs. Figured I would ask and see if their is a way to wire this configuration up using just one Concentric, as I saw no Diagrams on the SD website. Thanks

  • Richard Irons 6 years ago

    Probably the best explanation I’ve seen.

    Will you be going into stuff like coil switching, phase, series, etc?

    It would be interesting to see people wiring their guitars as you put these tutorials up.

    • Richard Irons 6 years ago

      Hi Luis – thanks for the compliment!

      The series will hopefully progress on to four-conductor humbucker wiring, series connections and so on, yes. First things first though – we’re still only on one pickup!

  • Richard Irons 6 years ago

    Stupid question. Why 500K pots on the humbuckers and 250k on the single coil? maybe answered my question humbuckers are 2 single coils. I’ve done a few home builds and always struggled with the wiring this is a great site and very helpful. Is there any difference apart from the mounting to a bridge and neck pickup.
    Photo of my build with jazz and 59’s great sound.

  • Richard Irons 6 years ago

    is it to much to ask for you to put technical schematics up….

  • Richard Irons 6 years ago

    What is the value of the capicitor? What the hell does .47 mean u fool? Uf? Pf etc. This is not electronically proper but some idiot crap

    • Richard Irons 6 years ago

      It means 0.47 picofarads,the capacitor value.Most wafer capacitors will have the capacitance value listed on one side.

      • Richard Irons 6 years ago

        I am afraid you are dead wrong on that Mr. Curry. “Picofard” values would have no audible tone control at all here. The value as written in the figure usually means microfarads, but can be confusing as other standards exist. There are other notations where the unit is in picofarads, but those would have “47k” stamped on it for this type of part. I agree that, unlike resistors, capacitor markings can be confusing. There is no reason to call someone a fool, Mr. Lacey, as people who work with these circuits a lot do not usually need to have the order of magnitude of the caps spelled out.

  • Richard Irons 6 years ago

    For reference, what kind of switch is that in the 2nd diagram in which both the hot and ground are wired to the switch? DPDT, DPST?

    Thank you, SD & Co., for creating this awesome site. I really enjoy it and appreciate that you have the initiative to share this information with the public.

  • Richard Irons 6 years ago

    why does Seymour suggest .047 caps but everyone else suggests or uses 22’s?

    • Richard Irons 6 years ago

      From GM Arts site (http://www.gmarts.org/index.php?go=236#bst_sc):

      “Manufacturers want you to hear a strong effect with the tone control, so they err on the side of being heavy handed by using capacitors as high as 0.047µF. These values were used on the first electric guitars, when they were envisaged doubling as a simulated bass guitar with no highs at all by rolling the tone right off. If you use and like that tone, there’s no reson to change, however, you
      can generally get sweeter tones with much lower capacitor values. I recommend starting with a much lower value around 0.0047µF then experiment within the range 0.0015µF to 0.015µF.”

      • Richard Irons 6 years ago

        That’s not entirely correct. Fender used .1µf for that bass sound, later reduced to .047µf and .022µf . Gibson used .022 capacitors in the 50’s and sometimes fitted higher value capacitors (and darker sounding potentiometers) in later years. I like .047 in my Fenders and 250k pots.

  • Richard Irons 6 years ago

    Hi,
    Is this blog still active?
    If so I have a quick question…

    Can you put the volume pot after the tone pot in the chain?
    If so, how does this change the wiring?

    Thanks!

  • Richard Irons 6 years ago

    Greenhorn question:
    Concerning the volume control sans tone control diagram:
    Each solder point for the ground connects separate wires, right? Meaning, 3 wires connecting pickup to pot casing, pot casing to lug, and lug to jack?

  • Richard Irons 6 years ago

    How do I eliminate the tone and add a blender pot? I have 2 les pauls with a single tone and I want to convert to a blender for the middle position using 2 pickups which for me is more useful since I never use the tone on the guitar
    Thanks

  • Richard Irons 6 years ago

    Hi Richard, I bought a prewired pickguard with a volume and tone control it has a metal bar on connecting the two post and then the capacitor is connected to the out leg on the tone pot to the in leg of the volume control. When I connect the hot and ground from the pickup I can get volume control but no tone control. I have attached a picture of what I have. I am not sure where to hook up the hot and ground from the pickup. Any insight would really be appreciated. Thanks, Gary B. gborelli@comcast.net

    • Richard Irons 6 years ago

      Gary, I also bought a pair of pots (volume / tone) pre-wired, and they are wired the same as your picture. I’ve been learning a lot about guitar wiring recently, but this pre-wiring does not tally in with what I have been learning. In theory, wiring this way bleeds the treble through the cap before it reaches the tone pot, therefore the slider will not adjust the amount of signal going through the cap and out to ground, but will probably reduce the volume, I don’t think it wouldn’t silence the volume completely, because you have some of the signal still going through the volume pot. But still, it’s seems daft wiring this way to me? It should be wired either as SD diagram above shows, or with the cap connected from one side of the pot to the top of the pot (out to ground) with the tone slider connected to the input on the volume pot

      • Richard Irons 6 years ago

        HI Luke,
        I agree with what you are saying. This one is made by gretsch guitars ( aka fender ) and is even used on one of the current models but they do not or will not supply a wiring diagram for it and the seller on Ebay is total jerk and was of no help. So I abandoned it and wired the pickup directly to the jack and for now it sounds fine until I have more time to work this out. I am going to try the wiring shown here and see what comes of it. If it works I will post the fix.

        Thanks,

        Gary

  • Richard Irons 6 years ago

    Novice here, just a music teacher trying to save $ and do it herself. I get most of the connections etc, but on the bass I have, there is also a red wire connecting the volume pot to the input jack. How does his relate to the other wires?

    • Richard Irons 6 years ago

      I believe this would be like the last pic in the article- that red wire is the one bringing the signal from the pickup to the volume pot to the output jack. The other wire coming off of the jack should be going to ground.

  • Richard Irons 6 years ago

    Hi, thanks for all this info, it is exactly what I need and explained very well, I wonder if you can help me with my project. I am going for a very simple setup, just a volume pot, no tone, can I add a capacitor somewhere in the circuit for the tone? I have seen a few diagrams with these orange drops added but they are all added to the tone pot, but I don’t intend to have such a thing.

    • Richard Irons 6 years ago

      You can permanently wire one, but it would always be cutting the highs (no control over how much). If you like guitars with no tone knob, don’t worry about having a capacitor at all.

  • Richard Irons 6 years ago

    Hello. for the
    “Turn It Up”
    version, do you should we strip the ground wire to weld it to the potter?

    • Richard Irons 6 years ago

      Yes, strip the end of the black wire, and solder it to the back of the pot or the 3rd lug (which then gets soldered to the back of the pot).

  • Richard Irons 6 years ago

    What will happen if I connect the third lug of the tone pot straight to the ground?
    Will I lose the signal completely or if I turn the pot halfway and then lose the signal?

  • Richard Irons 6 years ago

    What would happen if Id connect the hot to the wiper and the ends to ground/jack?
    Would it hum like not plugged in if I turned it to the ground side then?

  • Richard Irons 6 years ago

    Why not run the hot wire to the tone pot first, then to the vol pot? I don’t get how the signal is flowing to the vol hot lug and the tone ground lug simultaneously.

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