Understanding Guitar Pots and Caps
Guitar Pots and Caps Explained
Guitar potentiometers (pots) and capacitors (caps) are perhaps the least understood components in electric guitars, bass guitars. Learn what they are and how new pots and caps can improve the sound of your instrument.
The terms “pots” and “caps” are abbreviated terms for potentiometers and capacitors respectively. Pots and caps are part of the electrical system in electric guitars and bass guitars. They are located in hollow cavities in your instrument’s body, underneath control knobs. Your control knobs are installed on the shaft of the potentiometer thereby enabling you to make changes to tone and volume.
Guitar Pots Explained
What Do Guitar Pots Do?
A potentiometer is basically a component that allows you to progessively change what it controls. A light dimmer switch (which is technically a variable rheostat) is an example of being able to incrementally adjust power. The website ResistorGuide.com states this definition, “A resistor of which the ohmic resistance value can be adjusted. Either mechanically (potentiometer, rheostat) or electronically (digital potentiometer)”.1
Guitar pots are used to affect and control volume and tone. Volume control speaks for itself. Tone control enables you to change the sound, including how you mute or blend the signal from guitar pickups.
Types of Guitar Potentiometers
At a top level there are mini-pots and full-size pots. Potentiometer designs are short-shaft pots, long-shaft pots, and push-pull pots. Potentiometer designs also have split-shaft design, solid-shaft design. All pots shafts have splines (the rib-type grooves that run the length of the shaft). The shaft length, diameter and type of splines does affect the fitment of control knobs. When replacing pots you should note these critical dimensions. Some pot replacement jobs require modifying mounting holes and buying new control knobs.
For more detailed information you can read a great article on the PremierGuitar.com website. Of particular interest is a comment by author Dirk Wacker concerning Imperial vs. Metric installation issues. Mr. Wacker commented, “Now it’s time to discuss some typical pitfalls you might encounter when replacing pots or knobs on your guitar. The first scenario is a hot topic in guitar repair shops worldwide: installing U.S. pots (measured in inches) in a guitar that sports metric electronics.”2
PRO TIP: If your knobs are loose on split-shaft pots DO NOT try to pry open the gap in the shaft to make it wider! One side will shear off and you will have then ruined your new potentiometer.
Mini-pots vs Full-size Pots
Generally speaking, mini-pots are inferior to full-size pots. Using mini-pots is one-way manufacturers cut costs of making new guitars. While mini-pots (Alpha pots) are usually associated with low-end guitars, however; you sometimes find them on higher-end brands like Ibanez and Spector. If your guitar has mini-pots it’s not a huge problem: however, when it’s time to change your guitar pots you should look into upgrading to full-size guitar pots.
Mini Pots are recognized by their case (body) which is about the diameter of a dime. Mini-pot shafts usually have coarse splines and need 5/16″ round mounting holes.
Full Size Pots are recognized by their case (body) which is about the diameter of a quarter. Full-size pot shafts usually have fine splines needing 3/8″ round mounting holes.
500k vs 250k Tone Pots
Both 250k pots and 500k pots have their place in making a guitar sound great. Some guitar wiring circuit designs use 300k or even 1 Meg pots. Here’s what you need to know about choosing the right [pots for your guitar.
Generally speaking, to control volume, humbuckers should be paired to 500k pots, while single-coil pickups should be paired with 250k pots. A 500k volume pot offers twice the resistance to the current flowing from the pickup to the output jack versus a 250k pot when turned up to maximum.
When to Use 500k Pots
Humbuckers have far more windings than a single-coil pickup thus need a 500k pot (Gibson sometimes uses 300k pots). Because 500k pots are great for guitars with humbucker pickups they are the most commonly found in Gibson Les Paul, PRS, Dean, and Ibanez humbucker styled guitars.
When to Use 250k Pots
Because 250k pots are great for single-coil pickups they are the most common with Fender, Ibanez, Schecter, and similar guitars.
When to Use 1 Meg Pots
In some situations a 1 Meg pot can bring an amazing sound to a guitar. G&L uses 1 Meg pots for a bass roll-off. Telecasters, Gibsons, and others have used 1 Meg pots to greatly lift high tones. You may want to look at a different guitar (pickups) if you’re chasing a brighter sound.
When to Use 25k Pots
The use of 25k pots is typically found in smaller stringed instruments. It is often used in many instruments utilizing active electronics, in particular guitars using EMG humbucker pickups.
Volume Pots vs Tone Pots
Firstly, everyone wants to know if tone pots and volume pots are the same. There’s truly nothing made that is legitimately called a “tone pot” or a “volume pot”. This simply refers to where you choose to use any particular pot. However, there are best practices when choosing the type of pots you use for controlling tone and volume.
Industry experts such as the folks at Fralin Pickups recommend using audio taper pots for tone and volume controls.3
Linear Pots vs Audio Taper Pots
A great way of describing the difference between linear pots and audio taper pots can be found in a thread on StackExchange. Eric Gunnerson commented, “Very simply, with a linear taper, if you turn the pot halfway, the resistance measured on each side will be equal. With logarithmic (aka “audio”) taper, that is not true; the resistance follows a logarithmic progression. Log taper is used because it gives a more natural progression when used for volume control.”5
Linear Pots increase/decrease signals in a linear fashion. (“1” on your control knob equals 10%, “5” equals to 50%, etc.). Because of its predictability, many people prefer a linear pot for their volume control.
Audio Taper Pots, aka logarithmic pots, are non-linear potentiometers that deliver a more natural variance in sound when you turn your knobs. Audio taper pots compensate for the relationship between resistance and volume in a passive guitar circuit.
What Do Tone Pots Do?
The tone pots increase or decrease the flow of higher frequency signals to ground. The lower the resistance to this high-frequency sound loss the less shrill the sound. A high resistance tone pot can decrease the loss of high-frequency sound more than a low resistance tone pot.
What Are Push-Pull Pots
A push-pull pot is simply a potentiometer sitting on top of a switch. Fralin refers to this as, “…a DPDT (Double Pole, Double Throw) switch the switch has two separate poles.”4 The net effect is that it multiplies what you can do with the sound of your guitar.
Symptoms of Bad Pots
Signs of a bad potentiometer include a scratchy, static type noise (from your amp) when turning a knob or anything less than a smooth feel when you turn the knob.
You may not need to replace a pot that has signs of problems. Sometimes you simply need to clean the pot with a specially designed electronics contact cleaner.
PRO TIP: Always protect your guitar’s finish from possible harm when applying solvents, solutions, lubricants, and other foreign substances.
How Much Do Guitar Pots Cost
Guitar pots generally cost $6-$9 each. If you hire a guitar shop to install pots the labor should be about $30 for one and up to $75 for three. There could be an additional fee if a luthier needs to ream (enlarge) the mounting holes to accommodate the potentiometer’s shaft. Hollow-body guitars may be more expensive due to extra time required to pull and replace the circuit.
Tone and Volume Pots Wiring
There is a vast array of guitar wiring configurations. As you can imagine, multiply the number of pickup configurations by the number of knob configurations and you are well into the hundreds, if not thousands. Fortunately, there are some standard wiring configurations available online that work for almost any setup.
The best source we know for guitar wiring diagrams is at the Seymour Duncan website. They provide precise and accurate diagrams for a wide range of configurations.
What Are the Best Guitar Pots?
Ask people what is “the best” anything and you’ll get a lot of different answers. Identifying the best guitar pots is about the same. Below we have listed five guitar pots that consistently get good reviews. (We use DiMarzio, Emerson, and Seymour Duncan and always have stellar results.)
- DiMarzio (CTS) Potentiometers are always a solid contender for the best guitar pots. They are well made and competitively priced. They offer 250k and 500k pots ranging from $9-$15 each.
- Emerson Pro Pots (CTS) Potentiometers are custom made by CTS to Emerson specifications. Emerson Pro Pots are low torque and feature a proprietary custom audio taper that ware designed to maximize response (think turning down your volume to 2 and it’s the same effect as turning down your amp’s volume knob).
- Seymour Duncan (Bourns) Potentiometers are yet another example of the brilliant minds at Seymour Duncan. They make a YJM-500k pot, suitable for tone and volume controls, that will exceed your expectations. They 500k pots have a special lubricant that makes them ultra smooth for many years of use. These 500k pots cost around $14 each. They also offer their signature SD Pots, 250k or 500k, for only $9 each.
- Fender Stratocaster Potentiometers are obviously designed for Fender Strats. It’s a no-brainer that they are one of the best pots for a Strat guitar. Even better is you can buy a wiring kit with shielded wire, pots, input jack, 5-way switch and required installation hardware for under $120 from Artisan Luthiers. Go to the Fender website and you can buy individual pots for around $9 each.
- WD Music Potentiometers are really good and are reasonably priced. You can get a set of three for under $20 + shipping. They have a wide selection of Bourns, CGE, Alpha, and CTS pots from which to choose.
Guitar Capacitors Explained
What Do Capacitors Do?
Guitar caps are used to manipulate specific frequencies to shape tone. The tone pots and capacitors combine to create a low-pass filter. How you integrate it into your wiring plan adds another dimension to the manipulation of your tone.
When you opt to lower the pot your treble is throttled and your tone gets darker. Larger value caps reject less signal thereby allowing more to pass to ground. A larger cap value knocks down high frequencies faster which better exposes the midrange tones at lower volumes.
What Are the Difference in .022 vs .047 Tone Cap
The numbers assigned to a capacitor indicate its value. At lower volumes, the .022 cap will retain more highs than the .047 cap. What do the experts like? The sound experts at Seymour Duncan seem to have a strong preference for the .047 pot cap value. In fact, this is the most common choice for the vaunted treble bleed mod.
What Are the Best Guitar Caps?
In our opinion, the following are our top three caps for electric guitars (listed in no particular order).
- .047 Orange Drop Caps are very reliable and do a great job pushing mids at any volume level. These are often found in high-end guitars such as Fender, PRS, and Gibson. Sprague Orange Drop caps cost around $4 each + shipping.
- Black Beauty Caps Truly a vintage sound component, Black Beauty caps mute some high-end tones to soften tones that are smooth and rich. Black Beauties are best used with vintage cloth push-back wiring. Black Beauties caps cost around $25 each + shipping.
- Paper-in-Oil Caps Emerson still makes these amazing paper in oil caps that deliver a responsive warm, vintage tone. Emerson’s mod to sealed metal tubes means you get the sound with a much longer useful life. Paper-in-Oil caps cost around $18 each + shipping.
Pots and caps play an important role in sculpting your instruments sound output. If you want a lower-cost way to alter or improve your sound replacing or modifying your pots and caps may be right for you.
DISCLAIMER: The information provided in this article is for informational purposes. This information is not intended to be a guide or similar instructions. Guitar repairs and mods should be done by only qualified guitar techs or luthiers. Errors in installation and wiring will have negative outcomes. If you are uncertain about doing repairs or mods you should use the services of a local guitar tech or luthier.
- 1 ResistorGuide.com, “Variable Resistor”, March 15, 2014, Available from ResistorGuide.com
- 2 Dirk Wacker, “Mod Garage: Dealing with Knobs and Pots”, January 1, 2016, Available from Premier Guitar
- 3 Tyler Delsack, “How Do Volume and Tone Pots Work for Guitar?”, March 3, 2017, Available from Fralin Pickups
- 4 Tyler Delsack, “Push Pull Pot Power”, March 29, 2017, Available from Fralin Pickups
- 5 Eric Gunnerson, “Difference Between Linear and Audio Tapers”, November 30, 2012, Available from Stack Exchange