How Do Volume and Tone Pots Work For Guitar?
Volume Pots and Tone Pots are an integral part of your guitar’s tone and setup. By understanding your Volume Pots and Tone Pots a little more, you can make sure you pick the right Pot type and value for your guitar.
A Potentiometer (or “Pot” for short) is a type of variable resistor. By turning the Pot, you are changing the way electricity flows through it. Inside the Pot, there is a circular resistor strip or “element” that gets wiped by a “sweeper.”
Turning your knob changes the position of the Sweeper on the resistor strip. The Sweeper allows you to choose how far the electricity has to travel on the strip until it reaches its output.
A Pot is an “L-Pad,” which is an electrical device doing two things at once. It’s introducing Series Resistance and a Short across the signal. The Short is what dampens the high frequencies of the signal, even when the Pot is on “10”. For instance, if you have a 250K pot, you can choose any value from 0 – 250K.
To illustrate this further, take a look at the diagram below:
As you can see in Example A, the Pot has a Resistance Strip, made of resistive material, and a Sweeper. The Sweeper will sweep across the resistor strip to achieve the resistance you want.
For a 250K pot, the resistance of the Start of Sweep (Lug 1) and End of Sweep (Lug 3) is roughly 250K. The Middle lug is the Sweeper. This is how you get your variable resistance!
It’s important to note that manufacturers have tolerances – in reality, it might be 243K. You can check the resistance of your Pot by taking an ohm reading of the two outside lugs.
The Pot is the foundation for all the possibilities you can achieve. From Volume Pots to Tone Pots – let’s check out a few variations to see how we get many uses from one pot:
WHICH POT TO CHOOSE? 250K OR 500K?
Single Coil pickups and brighter-sounding pickups (think Strat, Tele) use 250K Pots.
Darker-sounding pickups (P-92, 43-Gauge Big Single, P-90’s, and Hum-Cancelling P-90’s) use 500K Pots.
The higher resistance pot won’t send your high frequencies to ground as quickly as 250K pots do. They sound brighter and allow more high frequencies to pass through the Pot. 250K Pots will send more high frequencies to ground, making the pot sound a tad darker.
Using the correct pot value is pleasing to the ear – we don’t want muddy sounding humbuckers, or piercing single-coil pickups. So, our pots help compensate and shape the tone right from the get-go.
There are Pots in the middle – we sell 300K Pots as well, which are a little brighter-sounding than 250K pots.
“The correct pot is the one that sounds the best.” Use your ears! You might like 500K pots on your single-coils, depending on what you are trying to achieve.Lindy Fralin
LINEAR VS. AUDIO TAPER?
We get asked about Linear and Audio Taper pots a lot. Despite choosing which resistance of Pot to go with, there are two types of Pot “Tapers.” Taper refers to how the sweep acts and sounds. Is it smooth and gradual? Or, quick and abrupt?
Linear pots are, well, linear. Imagine a straight line on a graph: electronically, your wiper and taper is just like that – a straight line. You would think that this is the end-all, be-all of pots, right? Well, the human ear doesn’t hear that way (there’s a thing called the Weber–Fechner law).
What happens? 90% of your perceived signal change is found in the first 25% of the turn. That means you turn your Pot a little bit, and the bulk of the change happens right there. Not very useful for specific applications.
AUDIO TAPER POTS:
Audio Taper pots are different from Linear pots as they are logarithmic. Imagine that straight line, only curved in the middle. The result is an exponential increase or decrease in resistance as you turn the Pot.
What happens? You experience a smoother change when you turn the Pot. This means that you can perceive a 50% loss in volume at the “5” mark!
We prefer Audio Taper Pots for Volume and Tone, but you can always experiment!
SPLIT SHAFT OR SOLID SHAFT?
This is all about the knob! If you have plastic knobs like a Strat, those require Split Shaft – you can simply slip the plastic knobs on.
Metal knobs with a set screw require Solid Shaft pots. For Metal knobs, you have to tighten the set screw onto the post.
Consequently, this is really hard to do with a Split Shaft, and you might break part of the shaft doing so. A quick fix is to use a “sleeve” which is a metal tube that goes over the Split Shaft, basically converting it to a Solid Shaft pot.
VOLUME POT BASICS:
Now that we’ve covered some of the most frequently asked questions, let’s dig into how pots work. Let’s start with Volume Pots:
On a Volume Pot, a basic set-up is this for a Gibson®, Strat® or Tele®:
- Input = Lug 1
- Output = Lug 2
- Ground To Casing = Lug 3
The third lug connects to ground. That means as the sweeper moves towards the grounded lug, more of your signal is sent to ground. When the pot is turned all the way counter-clockwise, all of your signal is being sent to ground, thus, no volume!
In Ex B, The Sweeper moves towards the grounded lug – which means some of your signal is being sent to ground. If the sweeper was turned all the way counter-clockwise, no signal would come through your amplifier.
In Ex C, your input and output are basically connected – zero resistance. Therefore, all of your signal is passing through the output lug.
If you didn’t ground Lug 3, your volume pot won’t work correctly. It will never give you zero output. In Examples B & C, the Output Jack is being Grounded. This works for 1 Volume guitars, like a Strat or a Tele.
WHAT IF YOU HAVE 2 PICKUPS AND WANT TO TURN DOWN THE INDIVIDUAL PICKUPS THEMSELVES?
To accomplish this, you change the order of the Lugs. Instead of Lug 1 being the input, Lug 1 is the output. The sweeper will be the Pickup itself, instead of the Output Jack. So, instead of connecting the Output Jack to Ground, the Pickup connects to Ground. This works well for Jazz Basses or P-J Basses. See Below Ex. Ba and Ca for a diagram for this type of wiring:
TONE POT BASICS:
A Tone Pot is nothing but a regular pot, with a capacitor soldered to it. A Tone Pot will work the same way as a Volume Pot, but just a little different.
Instead of sending the entire signal to ground, the tone cap helps by sending only a part of the signal to ground. Tone caps only let high frequencies pass through it – they resist, or reject low frequencies.
TONE CAP VALUES:
The value of the tone cap (.0025mfd, .02mfd, .1mfd, etc.) will determine the cut-off point for the highs. A smaller value (.0025mfd) will pass the least amount of highs. When rolled off, you will notice a subtle change in your high frequencies – you can only get your guitar to sound so dark.
A higher value of tone cap (.1mfd) will roll off the most amount of highs, getting into your high mids. You will get the darkest and deepest roll-off with higher value caps.
HERES HOW IT ALL COMES TOGETHER:
- You turn your Tone Pot counter-clockwise.
- Your signal starts to pass through the Tone Cap, which connects to ground. (Example D)
- The Tone Cap will reject the low frequencies, allowing the high frequencies to get sent to ground, thus making your tone sound darker.
SEE BELOW FOR AN ILLUSTRATION:
As you can see from Ex. D and Ex. E, the tone pot works pretty similarly to the regular Volume Pot. This time, we have our Tone Cap to help us fine-tune our tone!
WHAT IS A NO-LOAD POT?
Before we get into No-Load Pots, let’s talk about “Load”:
The definition of Load in terms of electricity is anything in a given circuit that “consumes” energy as opposed to sourcing (providing) energy.
Even on “10”, your tone pot is still “sucking up” electricity. The Sweeper (Middle Lug) is still technically on the Resistance Strip, which draws power from the Volume Pot.
On a No-Load pot, there is a break on the Resistance Strip where the Sweeper is taken completely out of the circuit. Using a No-Load Pot will make your pickups sound a little more “full-throttle”. They might sound a little bigger, fuller, with added bass and treble. This is all personal taste, and we can take them or leave them, depending on the guitar.
WHAT IS A BLENDER POT?
Lindy has installed a Blender Pot on almost every 3-pickup guitar he owns. A Blender Pot is a type of No-Load Pot that will “Blend” between two pickups that it’s wired to.
It’s a useful mod that allows you to get a lot of tone options – like Telecaster tones out of your Strat. While the Bridge is selected, turning the Blender Pot will blend in the Neck.
To illustrate a simple installation of a blender pot, check out this wiring diagram here.
Whew. Now you have a grip on the basics. I hope this article has been helpful. Now use your guru knowledge to create your own unique tonal combinations, and make sure you choose the pots that will work best for you.