Sound and gear

An unplugged electric guitar barely makes a sound: a solid body does not amplify like an acoustic's hollow box. What makes it "speak" is the pickup, and its principle is one of the great discoveries of the 19th century: Faraday's electromagnetic induction.

1. Under each string sits a magnet (or a magnetised metal pole piece).
2. Being close by, the steel string becomes slightly magnetised and becomes part of the magnetic field.
3. When the string vibrates, the field passing through the coil (thousands of turns of very thin wire) changes hundreds of times a second.
4. A changing magnetic field inside a coil induces a voltage: an alternating signal that copies the string's motion at the same frequency.

Listen to the open sixth string: the pickup would produce a signal rising and falling about 82 times a second, exactly the rhythm of the vibration.

Play: Low E (82 Hz), E an octave up (165 Hz) and two octaves up (330 Hz)

There are two big families of magnetic pickups. The difference starts with a problem: the coil does not only pick up the string, it also picks up hum from mains electricity (50 or 60 Hz), screens and transformers.

We call them single-coils and humbuckers (literally, "the one that bucks the hum"). Neither is better: they are different colours on the palette.

Position matters as much as type

The pickup selector does not just change the volume: it changes which harmonics you hear.

• Bridge pickup: near the fixed end of the string, where every mode of vibration moves little but the high harmonics weigh relatively more than the fundamental. Result: a bright, nasal, cutting sound. Ideal for riffs and solos that must cut through the band.
• Neck pickup: closer to the middle of the string, where the fundamental swings widely. Result: a round, warm sound with more lows. Ideal for sweet melodies, jazz or soft accompaniment.
• In-between positions: blend the two and sometimes sound "hollow" because some harmonics cancel between pickups.

And on the acoustic guitar

An acoustic already makes its own sound; to amplify it there are two routes, often combined:

• A piezo pickup under the saddle turns the strings' pressure into electricity. It works with nylon and survives high volume without feeding back, but it can sound dry and "quacky".
• A microphone (inside or outside the body) captures the air the guitar moves. It is the most natural option, but it feeds back (that howl) at high volume or near the speaker.

A guitar amplifier has three parts, and each leaves its fingerprint:

Gain and volume are not the same thing. Gain decides how much the signal saturates (character); the master decides how loud it is (level). Low gain and a high master give you a loud clean tone; high gain and a low master, a distortion for late-night playing.

Clean, overdrive and distortion: it is all clipping

When the gain pushes the signal beyond what the circuit can reproduce, the peaks of the wave flatten: that is clipping. As the wave changes shape, new harmonics appear, which is why the sound becomes richer, longer-sustaining and more aggressive.

• Clean: the whole wave gets through. You hear each note of the chord separately.
• Overdrive: soft clipping, like a tube amp being pushed. It responds to the pick: play softly and it cleans up, dig in and it roars.
• Distortion and fuzz: hard clipping. Lots of sustain, compression and harmonics.

Hear it: the same riff clean, with overdrive and with distortion. You can switch effects while it plays.

Theory deep diveWhy the power chord rules with distortion

Distortion does not only add harmonics to each note: it also creates intermodulation products, new frequencies born from the sums and differences of the notes you play together. With a perfect fifth (a ratio of about 3:2) those new frequencies line up with harmonics of the root and the chord sounds tight. With thirds (5:4) the new frequencies clash and the chord turns muddy. That is why, with lots of gain, the two-note power chord sounds bigger than a full chord.

Hear the difference with distortion: the fifth stays tight and the third turns muddy.

Play: E power chord with distortion: root, fifth and octave Play: Full E major with distortion: with the third

Tubes, transistors and modellers

The equaliser raises or lowers frequency regions. To use it well, it helps to know where the guitar's notes are: fundamentals run from about 82 Hz (open sixth string) to just over 1,300 Hz (24th fret of the first string), and their harmonics reach much higher.

Play: Four Es: 82, 165, 330 and 659 Hz

An effects pedal changes the signal between the guitar and the amp. There are hundreds, but nearly all belong to six families:

The signal chain is the order in which the signal passes through all of that. There is a usual order, and it works because each effect processes everything it receives:

1. Tuner first: it gets the purest signal and usually lets you mute it too.
2. Dynamics and filters: the compressor evens out what you are about to saturate; the wah usually goes here.
3. Gain: the heart of the sound.
4. Modulation: modulating an already saturated signal sounds controlled; the other way round, distortion "flattens" the movement.
5. Time last: echoes and room should repeat the finished sound. Distort an echo and every repeat becomes as loud as the original note, smearing everything.

Hear the gain and time families on the same phrase, already in that order: delay and reverb repeat the sound after the saturation.

A delay whose repeats land on the rhythmic grid melts into the groove; one that lands at random smears it. The maths is simple, because a minute has 60,000 milliseconds:

$$\text{ms} = \frac{60{,}000}{\text{BPM}} \times \text{fraction of the beat}$$

The fraction is 1 for a quarter note, 0.5 for an eighth note, 0.75 for a dotted eighth and $\tfrac{1}{3}$ for an eighth-note triplet.

The dotted-eighth trick

Play quarter notes into a dotted-eighth delay and every echo lands three sixteenths after the note. The combined result is a sixteenth-note rhythm that sounds much busier than what you are playing. This is what you hear (note, echo, note, echo…):

And this is how it sounds with a real delay: quarter notes at 120 BPM with echoes at 375 ms, the dotted eighth at that tempo. Compare it with the dry sound.

Theory deep diveReverb and pre-delay

Reverb simulates thousands of reflections so close together that you cannot tell them apart. Its types (room, hall, church, plate, spring) change the size and colour of the space. Pre-delay is the time before the tail starts: about 20–40 ms separates the note from its reverb and keeps the attack clear even in a big space. In general, the faster and denser the part, the less reverb and delay it needs.

Play: A minor arpeggio with a large-hall reverb

Practice

Work out your delay and play it

90–120 BPM8 min

1. Cover the table above and work out the nine values. Check afterwards.
2. Set the metronome to 100 BPM. Play one note per beat on any chord and sing the imaginary echo three sixteenths later ("ta… ta-ta… ta-ta").
3. If you have a delay pedal or processor, set it to 450 ms, one clearly audible repeat, and play quarter notes: you should hear exactly the rhythm above.

Goal: Work out the quarter, eighth and dotted-eighth times at 90, 100 and 120 BPM without a calculator, and play quarter notes for one minute while counting the echo's counter-rhythm.

You do not need a studio to record yourself well. You need to understand four things.

1. The input: an audio interface with an instrument (Hi-Z) input turns your signal into digital. You can record the guitar direct (and use a modeller on the computer) or put a dynamic microphone close to the speaker, aimed between the centre and the edge of the cone: towards the centre is brighter, towards the edge has more body.
2. The level: recording at 24 bits, aim for peaks around −12 to −6 dBFS. Never hit 0 dBFS: digital clipping is not overdrive, it is an ugly click you cannot remove.
3. Latency: if you hear your guitar late, lower the buffer size (64 or 128 samples) while recording and raise it when mixing.
4. Monitoring: closed headphones to record; to judge the sound, also listen on ordinary speakers, on your phone and at low volume.

Listen back with the guitar silent and a critical ear: do the notes start on time? Do they end when they should? Are strings ringing that should not? In the Lifelong practice stop you will turn that listening into a habit.

Two guitarists with the same gear sound different. The pick, its angle, where you strike the string and how firmly your fretting hand presses change the harmonics as much as a pedal does.

Try this original phrase three times without touching the amp: picking by the bridge, in the middle and over the 12th fret.

Practice

Three tones without touching a knob

70–90 BPM6 min

1. Play the phrase picking 2 cm from the bridge, then in the middle, then over the 12th fret. Same pick, same strength.
2. Repeat changing only the strength of your attack: very soft, medium, hard.
3. If you play with saturation, roll the guitar volume down to 7 and hear it clean up. Roll it back up for the final bend.
4. Record yourself and listen blind (shuffle the order).

Goal: Record the phrase three times (bridge, middle, 12th fret) and have someone, or yourself blind, tell each version apart by ear.

Spending wisely

No names or brands, just the order in which money goes furthest:

1. A professional setup for your guitar (action, intonation) and fresh strings: they change more than any pedal.
2. An amp or modeller that sounds good at your real volume. A huge amp that never goes past "1" is no use at home.
3. Good headphones and, if you record, a simple interface.
4. One or two effects you use in every song (usually a saturation and a delay or reverb).
5. Everything else, when a specific song asks for it.

The second-hand market is your friend, and trying gear with your own guitar before buying is worth more than any review.

Self-assessment

How does a magnetic pickup produce a signal?

AThe string touches the magnet and closes a circuitBThe steel string disturbs the magnetic field and the changing field induces a voltage in the coilCThe pickup captures sound in the air like a microphoneDThe wood vibrates and the coil measures it

Why does a humbucker hum less than a single-coil?

ATo sound brighterBBecause it has one bigger coilCBecause its two coils receive the hum out of phase and cancel it, while the string signal adds upDBecause it uses weaker magnets

At 100 BPM, what delay time is a dotted eighth?

A300 msB450 msC600 msD750 ms

Which signal-chain order is the most common?

ADelay → distortion → tuner → reverbBReverb → compressor → delay → overdriveCTuner → compressor → overdrive → chorus → delay → reverbDChorus → reverb → overdrive → tuner

Listen to the chord. What is it, and why is it the favourite of heavy distortion?

Listen

AA full major chord, with a thirdBA power chord: root, fifth and octave, no thirdCA full minor chord

Your guitar sounds huge on its own but vanishes with the band. Which EQ move helps first?

ABoost the bassBTurn the treble all the way upCLower the gain and raise the masterDKeep the mids present

Optional reinforcement in the portalExperiment with waves, harmonics and filters in the sound lab(opens in a new tab) Optional reinforcement in the portalWork out delay times for any tempo(opens in a new tab) Optional reinforcement in the portalGo deeper: effects and the signal chain(opens in a new tab)