Foundations of Tone
A Primer on Electric Guitar Systems
Foundations of Tone
A Primer on Electric Guitar Systems
Whenever guitar players get together to talk about things, everyone brings in their own opinions informed by their musical preferences and their personal experience. Here’s some information, opinions, and ideas about electric guitar tone, informed by my musical preferences (I like Pink Floyd, Smashing Pumpkins, The Cure, U2, and brash, noisy, experimental rock) and experience (most of my live playing has been praise and worship in a church environment). I hope you find some of the information helpful, although always bear in mind: “Your mileage may vary!”
Basics of tone
The foundation of an electric guitar player’s tone is the instrument, the amp, and the player’s technique. It’s important to never lose sight of these three legs that are the foundation of your tone. Discussion of tone often starts and ends with effect pedals or other tone-shaping tools. But remember: those tools only shape the tone that’s already there. At the fundamental level all you need to sound great is a quality instrument connected by a good cable to a quality amp. Instrument Not all electric guitars are created equal.
Apart from the cosmetic differences in how guitars look, and the ergonomic differences in how the components (switches, knobs, tremolo arm, etc.) are arranged, the components of a guitar also affect the tone. Factors include the body style (especially solid body vs hollow body), type of wood used in the neck and body, the type of finished applied to it, the neck shape and design, the strings used, the type, rating, and quality of the tone and volume controls, and the type and configuration of the nut, frets, and bridge. There are far too many options for each of the factors listed above to go through them all here, and many players like to have more than one guitar type available to take advantage of different instruments’ features. However, there are two aspects of instrument selection and maintenance that bear strongly on shaping tone, so I’ll discuss them here.
The first is the instrument’s “set up.” “Set up” refers to the process of setting the adjustable features of your guitar (such as bridge saddle, neck tension, etc.) to achieve the best possible intonation at all points on the fretboard. Setting up a guitar is part science and part art. Because setting up a guitar sometimes requires specialized tools, many players take their guitar to a reputable technician or luthier to get their instrument set up. Note that if you change the gauge of your strings more than one gauge up or down, you will likely want to set up your instrument to accommodate the different string gauge.
The instrument’s second major contribution to your tone is the pickups. Pickups are basically just magnets surrounded by coiled wire. Pickups sense the vibration of the strings, and convert those vibrations into an electrical signal. There are many different types of pickups, but here are the three most common used in electric guitars. “Single coil” pickups have a thin wire wound hundreds of times around six separate pole magnets set into a frame. The six “pole piece” magnets are frequently mounted at varying heights to account for different frequency ranges associated with the different strings. Many people (including me) love the chime and sparkle that defines single coil pickups. But… single coil pickups are more susceptible to picking up electromagnetic interference (resulting in unwanted hum or hiss, known as “60 cycle hum” because the frequency being detected is at 60Hz). “Humbucker” pickups are really a pair of single coil pickups wound in different directions around a single bar-type magnet. This reverse winding tends to cancel out the effect of electromagnetic interference (thus “bucking” the “hum” it can cause.) Humbuckers tend to be “hotter” pickups, meaning they produce a more robust electrical signal, which is easier to distort and provides more sustain. However, humbuckers’ extra punch sometimes comes at a cost in clarity and definition compared to single coils. “P90s” combine some features of single coil and humbucker pickups. They are single coil pickups, but the pole pieces are not themselves magnetic but are set in a single bar magnet, like a humbucker. P90s are, in my view, a uniquely voiced compromise solution between single coils and humbuckers. There are other types but these are the broad categories. And within each category the materials used and the winding pattern (including number of times the wire is wound around the pickup, and the pattern of the winding) combine to create the pickups’ output which can be expressed in electrical measurements, but is for most players a very subjective thing.
Many guitars, especially Stratocaster and Telecaster variants, will combine pickup types. You’ll commonly see H and S used to denote pickup configuration (for example, a “super strat” model Stratocaster is H-S-S, denoting a humbucker in the bridge position, and single coil pickups in the middle and neck position). Many Telecasters now offer a single coil in the bridge positions, with a P90 or a humbucker in the bridge.
Tone tends to be brighter and hotter from pickups near the bridge, and darker and warmer from pickups near the neck. Many vintage guitars have identical pickups in different positions but in modern guitars many pickups are designed to be used in either a bridge, middle, or neck position. Most modern pickups are “passive” meaning they produce signal based only on the potential energy contained in their magnets. However, some modern pickups are “active,” and require battery power to function. Active pickups are less susceptible to electromagnetic interference because they use active electric current to amplify the vibration detected by the pickups, and lower the impedance of the resulting signal before it leaves the guitar (more on that later, as the impedance presented to certain effect pedals can impact their tone.)
Amplifiers turn the vibration of a guitar string into a much louder sound. The vibration you create when you pluck a string is detected by a magnet in the pickup; the pickup discharges that vibration as a faint electrical signal through the wires and controls of your guitar and cable into the amp; the amp uses electrical circuitry to magnify (or “amplify”) that signal, and output it to the magnet of a speaker. The varying wavelengths presented to the speaker magnet causes the magnet to pulse. By attaching a speaker cone to the magnet, the speaker cone discharges the magnets pulsing wavelengths as physical vibration. That physical vibration causes the air to vibrate at the same wavelength, and that vibration of the air travels as sound waves through the air until it reaches your eardrum. The vibrating air causes your eardrum to vibrate; that vibration is received by nerves in your body which relay the information to your brain which interprets the information and produces a sensation of awesomeness….
Early amplifiers (like early TV sets, radios, and computers) were powered by vacuum tubes, which were used to magnify the signal received by the amplifier. Later, the development of solid state electrical components like diodes and transistors (“solid” as distinguished from empty “vacuum” tubes) allowed amplifiers – and many other electronic devices – to be produced much more cheaply. Tube amps tend to be more expensive to produce, but many players find the tone of tube amps to be warmer and more satisfying. However, solid state technology is so advanced these days it’s possible to get great tone from tube or solid state amps. Many amps combine tube and solid state technologies. Some amps have the actual amplifier circuit in one enclosure, and the speaker in a separate enclosure (referred to as the “head” and the “cabinet” respectively). Other have the entire amplifier system in a single enclosure (referred to as a “combo” amp.)
Different amp manufacturers tend to produce amps with common characteristics, including signature tones. Vox amps tend to be bright and jangly, evoking a “British invasion” sound. U2’s The Edge is a well-known Vox user. Fender amps tend to have deeply resonant clean tones with well-defined bass and treble response, with less emphasis on middle frequencies, and mild breakup when they begin to distort. Many American blues rockers rely on Fender amps. Marshall amps have great low-end sounds, and tend to break up quickly making them popular with hard rockers from Jimi Hendrix to the Smashing Pumpkins. All these companies offer tube or solid state amps, and there are tons of other great amp manufacturers.
When you push any speaker past a certain threshold it will be unable to perfectly reproduce the signal, and the sound wave will start to become distorted. Many early guitar players liked this distorted sound, and thus pushed their amps hard – and loud – on purpose to get that sound. At some point, people started to experiment with other ways to distort, modify, and otherwise alter the electrical signal between your guitar’s strings and the amplifier’s speaker cone. Let’s talk about these “effects….”
After the first effect – distortion – was discovered by accident, players started experimenting with other ways to shake things up. The earliest effect developed deliberately was tremolo, which is nothing more than the rise and fall of the amp’s volume at a specified speed and depth. Later on, manufacturers attempted to re-create that cool space and echo you get when you play loudly in a big space by using springs to cause the amp’s signal to reverberate, producing “reverb.” Tremolo and reverb became relatively common features on amps, and remain so today. Eventually, manufacturers began developing effects housed in their own enclosures: you see them today as effect pedals, rack-mounted effects, or options included in amplifiers or instruments themselves. Today, it’s common for players to have a few different effects, often secured together on a pedalboard for convenience. Before I talk about individual effects, a few foundational concepts: power, patching, impedance, and effect order.
Most guitar effects require electric power, and it’s important to power your effects correctly. Early effects were powered by batteries and most still can be. More recently, effects included an option to use AC power via an attached or external power cable. Most effects these days have a port for an external power source. It’s important to use the correct power for two reasons: safety and tone.
Safety first: there are numerous problems (including dangerous electrical shock and the risk of an electrical fire) that can occur if you don’t use the correct power. Here’s how to tell your power source is correct:
Be sure you use the right one, or you’ll fry the effect and possibly the power source! Some effects use other form factors for their power sources: be sure you understand the polarity before plugging it in. (In this image, the dot in the center refers to the interior of a barrel-shaped power supply tip; the c-shaped figure in the center refers to the outside surface of the power supply tip.)
How you power your effects can also affect their tone. Electric current flows to a common ground, and ideally there is only one path to ground. If a system has multiple paths to ground, you run the risk of creating a “ground loop” where the current cycles back on itself instead of flowing to ground. This can happen when effects’ power supplies are “daisy-chained” together from a single power source. This “ground loop” acts as a powerful antenna that receives electromagnetic interference, but cannot discharge it to electrical ground… it circles around and around your signal path in a “loop” and results in hum or other undesirable impacts to your tone.
The solution is to ensure that each of your power sources is ground-isolated from the others. You can do this by powering your effects with batteries, by using separate individual power sources for them, or by using a multi-port power source with isolated power ports.
Note that not all multi-port power sources have true isolated ground (meaning each port on the power source has its own, separate transformer). Unhelpfully, many power supplies are marketed as “isolated power” when in fact the differing ports share a common ground, and are NOT ground-isolated. (Generally, these power supply vendors want to leverage the marketing power of “isolated power,” but what is really happening is internal switching to share max available amperage between all available ports… not separation of the electrical ground). If the power cable for a power source terminates in a “wall wart” (large, block-type transformer where the AC plugs are located) that’s a good indication the ports of that power source are not ground-isolated from each other. Most multi-port power sources from Voodoo Labs, Cioks, Walrus Audio, and the Fuel Tank series are properly ground-isolated. These power sources can be a bit pricey, but they’re essential to retaining the good foundation of your tone.
The worst possible power supply options are “daisy chain” power adapters, which have multiple tips powered by a single power source. These invite ground loop problems. If you do choose to use one of these, be aware that in addition to ground loop issues, one must also be mindful of the combined current draw of all of your pedals. For example, if I use a single 9V DC power source providing 200mA to power a SuperEgo (requiring 140mA at 9v) and a Memory Man (requiring 140mA at 9v), I’m exceeding the capability of the power source by trying to draw 280mA from it. The pedals may malfunction, and the power source may overheat.
Patching: This refers to how you physically incorporate effects into the signal path between your guitar and your amp. Technically, it includes the instrument cables as well. Your tone is only as strong as its weakest link, and some players who have amazing instruments and top-flight effects cheat themselves by connecting them together with poorly constructed cables. Cables which are poorly shielded tend to pick up electromagnetic interference which creates hiss or hum in your tone. High-quality shielding in a cable doesn’t act as a barrier to electromagnetic interference as such; rather, it functions more like a drain by creating a path of low impedance path to ground that allows the electromagnetic energy to follow a path of least resistance to ground (where you want it). This keeps the electromagnetic interference from reaching the wire carrying your audio signal (located at the center of your cable) and thus out of your signal path. Mogami cables are great pre-fabricated options for shielded instrument cables and patch cables; you can also get kits from George L or Lava to assemble your own instrument and patch cables without needing to solder.
If you assemble cables yourself, be sure you do it correctly. Some players disfavor solderless cables citing a high failure rate: however, these cables function as reliably as soldered cables if they are assembled correctly. I use George L’s in my rig, so I can explain their use their use the best. Here’s a quick tutorial on using George L’s patch cables. (This will move to its own section, with pics and a demo video, later this summer):
Impedance refers to the amount of resistance an audio signal faces as it passes through cables and circuits. Assuming your instrument uses passive pickups, your signal leaves the guitar as a “high impedance” signal, meaning it is easily “impeded” in its path. This matters for your tone because a high impedance signal passing through a long path (either a long cable or a large effects rig) degrades as it transits. The first element of the signal to degrade is the high frequency range of your tone; this makes your tone sound relatively darker or muddier as it passes through more and more cable; the phenomenon is often referred to as “sucking tone.” There are two cures for this: keep your cables and effect chain very short, or introduce “buffers” into your signal path.
Buffers lower the impedance of your guitar’s signal, letting it traverse longer signal paths without losing any sound quality. Buffers can be standalone devices, or more commonly many pedals (such as those offered by Boss) are “buffered” in bypass mode. (Other pedals are “true bypass” meaning when the effect is bypassed, no buffer is applied; rather the signal passes another few inches of signal path contained in the pedal switch and enclosure).
Two considerations when using buffers: some buffers are low-quality and can themselves hurt your tone, and some effects only work properly with an un-buffered high-impedance signal. In particular, fuzz does not generally respond well after a buffer. My preferred method of impedance management is to have a “master buffer” which is always on, ensuring that my signal is always buffered by the same high-quality buffer no matter what effects I have on. High quality master buffers include the Empress Buffer+, and the Radial Tonebone series of switchers.
The effects you use shape your tone, and the order in which your signal passes through effects matters. Different effects interact differently with each other, and with your guitar/amp pairing, depending on the effect order. Unlike principles of power and grounding, there are no hard and fast rules about effect order. In fact, you can use effect order switching tools to change up effect order while you play, and achieve a more diverse range of tone options. However, a widely used framework for effects is as follows: filter > distortion > modulation > volume > time-based effects (more conventionally, delay followed by reverb). Some effects like boosters and compressors are used in so many varying ways there is no convention for placement. I’ll discuss individual effect types in the order I just listed.
Filter effects include phase shifters, wah wah pedals, and envelope filters. Each of these applies a variable “filter” to the guitar signal, letting different frequencies pass through a constantly changing filter. The basic idea of all filter effects is the same, and at the right settings can produce similar sounds. The biggest difference is the method used to shift the filter:
Filters are usually first in the chain, although (especially for phasers) it’s worth experimenting. In almost all cases, filters act very differently before distortion versus after distortion.
Distortion is the easiest effect to understand, but actually exists in a wide range of tones. All distortion works by “clipping” the audio signal, i.e. forcing it to exceed a threshold somewhere in your chain. You can do this by driving your amp beyond certain parameters, or you can do it at lower volumes through a distortion pedal, which pushes the signal through electrical components designed to clip the audio signal. There is no formal taxonomy of distortion sounds, and some distortion effects could be classified different ways. Sometimes the term “gain” is used interchangeably with “distortion” and through they aren’t technically equivalent concepts, when used in a guitar overdrive or distortion effect “more gain” means “more distortion.” However, here is a generally accepted list of distortion types:
Designed to achieve the sound of an amp pushed to the point where the sound naturally breaks up and distorts. Because natural amp breakup often only occurs at very high volume, overdrive effects can achieve this sound at a more manageable volume level. Overdrive is used in all types of music. Popular families of overdrive include the Tube Screamer, Blues Driver, Blues Breaker, and KLON variants… multiple versions of each circuit abound. Overdrive families are generally distinguished by their range of gain or distortion (high, medium, or low), and by their tone characteristics (flat EQ, mid-boost, or mid-scoop). There are too many overdrive builders to hope to list here, but outstanding overdrives can be found from big name companies and boutique builders.
Designed to clip at a much harsher level. You can get distortion sounds from an amp pushed very hard, and like overdrive distortion pedals mimic that sound. Popular variants include the MXR Distortion +, Boss DS-1, and ZVEX Box of Rock. But there are thousands of others… Outstanding distortion tones can be found from big name companies and boutique builders.
Fuzz was one of the first guitar effects to be produced for commercial use. Fuzz is a harsh destruction of the guitar’s signal and can be an unruly effect. In the 60s you heard it in Jimi Hendrix and Iron Butterfly; today it pervades alternative rock. Personally, it’s my favorite tone shaping tool but it’s not for everyone. Some great fuzz builders today include Analogman, Monsterpiece, and Devi Ever.
Big Muff and Rat:
Two types of distortion deserve special mention because they are so prevalent, and because they span distortion types. The ProCo Rat is a dirty, flexible distortion pedal that can get into fuzz territory but can also be dialed down to serve as an overdrive. The Big Muff from Electro-Harmonix has existed in several circuit configurations, and has been cloned by multiple builders. It can produce tones that range from smooth violin-like lead lines to raspy, spitty fuzz. Well-known users include Pink Floyd/The Wall (early 70’s “Rams Head” circuit Big Muff), Smashing Pumpkins (late 70’s “Op Amp” circuit Big Muff), Pink Floyd/Division Bell (90’s “Russian” circuit Big Muff), and Jack White (2000s-present “NYC re-issue” circuit Big Muff). Lots of builders offer Big Muff clones and derivatives, and none are finer than those offered by Matt Pasquarela at Stomp Under Foot.
Modulation effects change a guitar’s sound by bending, shifting, or multiplying it. Here are some common modulation types:
There are four basic volume effects:
There are two basic time effects: The first is delay or echo, a somewhat self-explanatory effect. Delay and echo effects can be very straightforward, or highly tweakable. One prominent feature in many delay effects is tap tempo, which lets a players “tap” a switch in time with the music to shift the delay time from song to song. This is very useful for live use. The biggest distinction between types of delay/echo effects is whether the effect is analog or digital. Many players feel analog delay is warmer and more “natural” sounding; however digital delay is often much more affordable and with today’s digital technology can sound very similar to analog. Some players prefer the pristine tone and tweakable options of digital delay. Some well-known delay effects include the Electro-Harmonix Memory Man, the Ibanez DE-7, Boss DD-7, and the MXR Carbon Copy. Higher end delays with tap tempo include the Strymon Timeline, Empress Superdelay, and Eventide Timefactor. A new delay pedal by Free The Tone (called Flight Time) actually has a small microphone and sets the delay to correspond to the beat it hears from the drummer. Some of the most famous use of delay effects are heard on U2’s Joshua Tree album.
The second is reverb. Reverb can be understood as mimicking a sound produced in a particular space; thus some reverb types are described as “hall,” “church,” or “room” to replicate those spaces. However, other reverb types can achieve spacy, ambient sounds. There are many outstanding reverb effects available. Reverb is another effect commonly incorporated into amplifiers. Great reverbs include the Electro-Harmonix Holy Grail, the TC Electronic Hall of Fame, the Neunaber Wet series of reverbs, and the Strymon Blue Sky and Big Sky.
Stuff Many other effects which achieve quirky or limited purpose type effects. I’ll mention one by way of example: the Electro-Harmonix Super Ego synth engine. This effect takes a momentary snapshot of your guitar’s signal and sustains it indefinitely. It also has the option to pass the sustained signal through an effects loop that modifies the sustained signal while letting your continued playing pass through unaffected. The practical effect of this is to produce keyboard synth/pad type sounds under which you can continue a lead or rhythm guitar part.
Effects: Multi-Effect Units
In lieu of a pedalboard physically assembling separate effects together, many players opt for a single digital multi-effect unit. These are available from many manufacturers. Budget models are available from Digitech and Zoom; more advanced devices are available from Line 6 and Boss; and high-end professional gear is available from Fractal and other companies. These devices often include many of the tone effects discussed above, with several foot switches to toggle particular effects or banks of effects. Tones are often shaped via menu-based editors, or commonly via computer or tablet interface. In general, the effects in a multi-effect unit shape your tone the same way as separate pedal units. There are pros and cons to using a multi-effect unit vice separate pedals. Maybe I’ll write more about that another time.
Putting it all together: Here are some “rig rundowns” of players’ electric guitar rigs, offered by way of example to synthesize all these concepts.
P&W Rig Rundown: http://www.toddpennington.com/node/105.
Andy Prickett Rig Rundown: andyprickett.com. (Andy plays guitar for several of my favorite bands, including CUSH, The Black Lantern, The Prayer Chain, The Violet Burning, and One Republic).
Jeffrey Kunde rig rundown: jeffreykunde.com. (Jeff plays guitar for Jesus Culture and a bunch of other P&W artists).