The Tone Control Capacitor
The tone control capacitor is often one of the most misunderstood components of the electric guitar. In this short guide, we’ll discuss how it works and how to choose the one that’s best for your instrument.The tone control capacitor resides in the control compartment of the guitar, where all of the electronics are stored. This component is usually attached to the tone control, and it’s the only difference in construction between the tone control and the volume control.
Tone Control Capacitor Types
Quite often, the capacitor will be the “ceramic disc” type, resembling the image in Fig 1.
However, most high-end guitar makers will opt for a better quality capacitor. These manufacturers will use a Mylar or “poly-film” capacitor, as seen in Fig 2.
What is a Capacitor?
A capacitor is a useful device common in electronics, and serves several purposes, including storing electricity like a battery and acting as a filter. In our tone control circuit, the capacitor is used for its filtering ability.
You can build a capacitor yourself by placing a strip of cardboard between two sheets of aluminum foil and rolling them up. One layer becomes the positive and the other becomes the negative. Homemade capacitors don’t work as well as manufactured ones — store-bought versions have higher standard or “tolerance” than a DIY one would.
How Does it Work?
The capacitor is a filter in our tone circuit, which has a value. The higher the value of the capacitor, the stronger the filter it is. A stronger filter will remove more high-end frequencies, which will result in a warmer, sometimes “muddier” tone.
How Do You Choose the Right Value?
There is only one sure way to choose the right value, and that is to listen to your guitar when you use the tone control. These are the things you want to listen to while you are playing:
- Your Tone – Does it get too dark and muddy when you turn down the tone; maybe it doesn’t get dark enough?
- Tone Control Travel – Does the tone change a lot when you turn down the knob a tiny, bit but then stay pretty much the same the rest of the way, or is there smooth travel from bright to dark?
If you’re disappointed by the way you respond to those questions, you might want to take a look at the value of your capacitor.
Standard Capacitor Values
There have been several standard capacitor values over the years, and two are still very popular today: the .047uf, and the .022 uf. To a lesser degree, you might find some guitars that have a .1 or a .033uf capacitor.
The Importance of Using Your Ears
There are plenty of guitar players who feel that all of the standard values are too high. They say the standard values result in a tone that’s too warm, and that the tone goes from bright to dark too quickly when turning the tone control up and down. A lower value capacitor in the .01uf range could result in a more usable tone with more tone control travel between the brightest and darkest tones.
The bottom line is that there are too many tonewoods, pickup models, foot pedals, amps, etc., that affect your tone to give a general answer. If you’re entirely at a loss, we recommend starting with the .022uf capacitor to see what you think and go from there. If the tone is too dark, try a .015 or a .01uf capacitor instead. If your tone is too bright, try the .033 or .047uf capacitor.
Choosing the Capacitor That’s Best for You
There are many types of capacitors available to the guitar player, including ceramic disc, mylar, paper in oil, aluminum, and more. Unfortunately, there are just as many heated battles over which type works the best. Once again, we recommend that you use what’s available to you, and to use your ears to make the final decision.
Ceramic disc capacitors are often used in inexpensive guitars because they are cheap. Higher-end guitars typically use the higher quality mylar capacitors. The real difference between the two is the tolerance. Tolerance means how close the component is likely to be to its listed value.
Cheap ceramic disc capacitors have a high tolerance (20% or worse). High tolerance means when you buy a .022uf capacitor, you might instead get a .03 or a .015. High tolerance leads to a very unpredictable tone from one guitar to another because the actual value of the capacitor can vary wildly. The chance of getting the correct value is low when using capacitors with a high tolerance.
More expensive capacitors have a low tolerance (5% or better). Low tolerance means you are likely to get a tone control capacitor with a value pretty close to what you are expecting.
Mylar Capacitors and Other Considerations
We recommend to use higher quality mylar capacitors or any tone control capacitor with a low tolerance. There are a few other things that we would like a guitarist to keep in mind, though:
- The tone control capacitor is in the path to ground. You don’t hear any sound that goes through it, only the sound that doesn’t.
- The guitar only works with a small voltage, so there is no need to buy a capacitor rated for 400 volts. Higher voltage has nothing to do with the operation of the capacitor, and will only add cost and size to the component.
- You can test the actual value of a tone control capacitor with a voltmeter. Testing means you can make sure you are using the exact value you need regardless of tolerance. We contend that all types of capacitors will sound the same if they have equal value.
We hope you’ve found this guide on tone control capacitors helpful, and we hope this information will aid you in improving your sound. Remember to use your ears to guide your tone, and make changes accordingly. If you enjoyed this article, please feel free to share it on Facebook and Twitter. Also, take a look around humbuckersoup.com for more articles on guitar electronics.