Guitar Tone Capacitors are capacitors used in the tone circuits of electric guitars.
Rationale
Why should you replace your tone cap?
- Because if you can solder and like to tinker it's a cheap <$20 project that can have a major impact on your tone.
Function
What does the capacitor do?
- The capacitor is for use in a low pass filter to process the signal between the pickups the output jack. It allows high frequencies to pass to ground rather than to stay with the signal. The range of frequencies it cuts varies depending on the capacitor value and how high you have the tone knob adjusted. The tone knob, a potentiometer, varies the amount sent to ground by reducing the resistance to ground.
If all it's doing is letting part of the signal go to the ground, then how does it have any effect on tone?
- Conservation of energy. If the signal isn't being sent to ground it has to be sent somewhere, i.e. to the amplifier.
Values
How are capacitors labeled?
- In microfarads. "µF" or "mfd". Occasionally nano or pico farads as well. (micro is 10E-6, nano is 10E-9, pico is 10E-12.)
- Sometimes in a three digit code in picofarads. e.g. 223 = 22,000 pF = 22 nF = 0.022 µF.
What value capacitors are popular in guitar tone circuits and why?
- Most popular are 0.01 µF, 0.022, 0.047, and 0.1.
- Lower values retain more high frequencies and are less likely to sound muddy.
- Higher values affect a broader range of frequencies and sound warmer.
What about Stratocasters vs. Les Pauls?
- Single coil guitars like Strats typically have 0.022 or 0.047
- Humbuckers like Les Pauls typically have 0.022 or 0.01
How have values changed over time?
- 1950's and pre-CBS 1960's strats all had 0.1 µF capacitors.
- Newer strats have 0.022 or 0.047 for the most part
Do certain pickups sound better with certain values?
- Yes. In general, brighter pickups sound better with higher values. Low output pickups (e.g. vintage) sound better with higher values.
What about tone pots?
- Tone pots are usually 250K or 500K. The latter sound brighter and are more often used with humbuckers.
How do I know what's in my guitar now?
- Look on the manufacturer's website or call them. Have the guitar's serial number ready if you call.
What's a no load tone circuit?
- One that takes the low pass filter out, so that all the signal is sent to the amp. Dick Dale uses one.
- These exist because even with the tone knob at 10, some signal is lost to ground.
Materials
What types of capacitors are there?
- Polypropylene (e.g. Orange Drops 715 and 716)
- Mylar, a.k.a. Polyester (e.g. Orange Drops 225, Mallory, little green Chicklets, most plastic caps in guitars)
- Paper in wax (stock in the earliest Stratocasters, now being remade by Ampohm.)
- Paper in oil (e.g. Vitamin Q. Used in guidance systems for ICBMs)
- Ceramic (disc shape)
What is metallized plastic?
- Mylar and polypropylene can be manufactured with metal to make a single sheet, commonly experienced as snack food wrappers and pretty balloons.
- Plastic capacitors can also be made with separate layers, known as film/foil capacitors.
What's the cost factor?
- You can get any of them for under $20, so get what you like.
What's the size?
- Large value caps can get big, and this can be problem with everything except ceramic.
What's the deal with voltage?
- Guitars run less than 1 volt. Most capacitors are rated 50 volts or higher. There is no advantage to higher voltage ratings than 50 volts.
- Acme Guitar Works sells an Orange Drop 716 with radial leads in a 100V size, nice because polypropylene caps tend to run big and are more often 400V.
Are there disadvantages to higher voltage ratings?
- It makes the cap bigger, harder to solder in and harder to get into the electronics cavity of the guitar.
How consistent are they?
- Capacitors are usually rated 1%, 5%, 10%, or 20%. You can measure with a meter or order ones with a low tolerance if you want to know what you're getting.
What kind of lead materials to they have?
- Steel or plated copper (nicer, on Orange Drop 716).
How are the leads arranged?
- Axial - on the ends, or
- Radial - out to the side
What's an Orange Drop?
- Brand name for a line of capacitors originally manufactured by Sprague, then Vishay Sprague, currently SBE (SB Electronics).
- Made in USA.
- They are film/foil or metallized plastic, and polypropylene or polyester (Mylar).
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