Hard rock

History and character

Hard rock is the heavier, louder, more distorted side of rock, born between the late 1960s and the early 1970s from British blues rock pushed to maximum volume: Deep Purple, early Led Zeppelin, Free, Black Sabbath (who would lead to metal), then Bad Company, UFO, Thin Lizzy, Rainbow, Aerosmith, Kiss, and above all AC/DC (from 1975 in Australia, then worldwide). In the 1980s Van Halen, Whitesnake, Def Leppard, and Guns N' Roses take it into the stadiums; in the 1990s it survives in bands like Aerosmith and in more alternative versions, and in the 2000s in bands like Wolfmother, Airbourne, Rival Sons, Greta Van Fleet.

Compared to classic rock, hard rock is more riff-centric: the song is born from a guitar riff in power chords or open strings, played through pushed tube amps (Marshall Plexi, JCM800), and has a solid, "square" midtempo groove. The solos are virtuosic (Ritchie Blackmore, Eddie Van Halen, Slash) and the vocals high and raspy, at the edge of a scream.

The genre sits halfway between blues rock and heavy metal: from the blues it takes the pentatonic scale, the shuffle, and call and response; from metal it anticipates volume, distortion, palm muting, and theatrical grandeur.

Scales and keys

Minor pentatonic ("box" position and open strings)

• Formula: 1 b3 4 5 b7 — semitones 3-2-2-3-2.
• Example in A: A C D E G; in E: E G A B D.
• Characteristic note: b3 over a major chord and b7; the 4→5 bend (D→E) is the "cry" of the hard rock solo.
• Chords: A5 C5 D5 E5 G5.
• Use: riffs (AC/DC play almost always in A, E, G with open strings), solos by Angus Young, Slash, Joe Perry.
• Real example: AC/DC — Highway to Hell (riff A–D/F#–G, open voicings); Aerosmith — Walk This Way (riff in C minor pentatonic with a b5).
• Common mistakes: using too much gain and losing the notes of the riff; out-of-tune bends.

Blues

• Formula: 1 b3 4 b5 5 b7. In E: E G A Bb B D.
• Characteristic note: b5 (Bb) as a chromatic passing tone.
• Use: riffs with an A5–Bb5–B5 passage or solos with the b5 in triplets (Slash, Ritchie Blackmore).
• Real example: Deep Purple — Smoke on the Water.

Mixolydian

• Formula: 1 2 3 4 5 6 b7. In E: E F# G# A B C# D.
• Characteristic note: b7 (D) → bVII chord.
• Chords in E: I E, ii F#m, iii° G#dim, IV A, v Bm, vi C#m, bVII D.
• Use: E–D–A choruses, open riffs in the AC/DC and Van Halen style.
• Real example: AC/DC — You Shook Me All Night Long (G–C–D with a Mixolydian approach in the riffs); Van Halen — Panama.

Aeolian

• Formula: 1 2 b3 4 5 b6 b7. In E: E F# G A B C D.
• Chords: i Em, ii° F#dim, III G, iv Am, v Bm, VI C, VII D.
• Use: darker riffs (Rainbow, UFO), minor power ballads, melodic solos over VI–VII–i.

Harmonic minor and diminished (virtuosic solos)

• Harmonic minor: 1 2 b3 4 5 b6 7. In A: A B C D E F G#. The raised 7 gives the dominant arpeggio E–G#–B–D and the diminished arpeggio G#–B–D–F (a substitute for V7).
• Use: Ritchie Blackmore (Rainbow — Gates of Babylon) and neoclassical guitarists; in hard rock only for moments of virtuosity.
• Common mistakes: playing the scale from beginning to end; better to use arpeggios of Am, Dm, E and diminished passages over the V.

Major / composite pentatonic

• Formula: 1 2 3 5 6; composite = major + minor. In A: A B C C# D E F# G.
• Use: solos over major progressions (Slash in Sweet Child O' Mine, Angus Young in the boogies), licks with b3→3.

How to choose

• Riffs: minor pentatonic/blues, with open strings in the keys of A, E, D, G.
• A chorus that "opens up": Mixolydian. Dark verse or minor ballad: Aeolian.
• Solo: pentatonic as a base, composite for sweetness, harmonic minor/diminished for a virtuosic passage over the V.

Harmony

Function

Hard rock harmony is built on the riff: the notes of the riff define the implied chords and the power chords keep the third out of the sound, so the same song can have a "minor" verse (pentatonic) and a "major" chorus (Mixolydian). The cadences are plagal (IV–I, bVII–I), with the V–I reserved for blues turnaround passages or power ballads.

Loops and riffs

• 1–2 bar riffs repeated in the verse; the chorus changes riff or moves to full chords.
• Open chords against an open string: the quintessential AC/DC voicing (A5, D/F#, G5, D-shape and C-shape chords over the open A string).
• Harmonic rhythm: one chord every half bar in the riffs, one per bar in the choruses.

Borrowed chords and colors

• bIII–IV–I (C–D–A in A) and bVI–bVII–I (F–G–A): the minor degrees inside the major.
• Sus4 and add9 chords that resolve (Dsus4–D).
• In the bridges, a move to the relative minor or to the bVI for an "epic moment".

Power ballad

• Pop progressions (I–V–vi–IV), clean arpeggios with chorus, add9 chords, a whole-step modulation in the final chorus.

Voicings

• Power chords with the octave (A5: A–E–A) on strings 6-5-4 or 5-4-3; open chords; triads on the G string for the second guitars. No jazz extensions: at most sus2, sus4, add9, and dominant seventh chords in boogie songs.

Typical progressions

Rhythm and groove

4/4 with a very heavy backbeat, straight eighth notes and an almost always midtempo pace (90–130). Hard rock lives on simple, unshakable grooves: the model is Phil Rudd of AC/DC, who plays eighth-note hi-hat, kick on 1 and 3, and snare on 2 and 4 with almost no variation. The accents come from the riff, with rests (stops) and syncopations of the guitar on "2&" and "4&". Many songs have the shuffle (boogie) or half-time sections. The typical microtiming: precise rhythm guitar, snare slightly behind, vocals free on top.

Drums

Role

Solid, powerful, no-frills drums: they are the "floor" on which the riff can move. Fewer fills than classic rock, more weight on every hit.

Kick

• On 1 and 3 (steps 1 and 9), doubled by the bass; variations with "2&" or "3&" only where the riff asks for it.
• Sound: 22"–24" kick with a peak at 60–70 Hz and moderate attack.

Snare

• 2 and 4 (steps 5 and 13), always rimshot, constant and high velocity (110–127).
• Medium-low tuning, with a tail and a bit of reverb (plate or room).
• Very few ghost notes (except in the funkier songs, e.g. Aerosmith).

Hi-hat, ride, and cymbals

• Half-open hi-hat in eighth notes (the AC/DC sound), or closed in the verse and open in the chorus.
• Crash on the 1 of each section and on the accents of the riff, ride in the solo.

Interaction with the riff

• The drums play the stops with the band (accent + rest) and leave gaps where the riff has its rests.
• The bass plays continuous eighth notes: kick and bass form a single block.

Sections

• Intro: often just guitar, then the band comes in with a crash. Verse: tight groove. Chorus: open hi-hat and crash every 2–4 bars. Solo: ride or open hi-hat, kick more present. Ending: repeated stops and a long roll.

Fills

• Few and short: 2–4 sixteenth notes on the snare, a run around the toms before the final chorus. In 1980s hard rock (Tommy Lee, Alex Van Halen) more spectacular fills with double kick.

Sounds and programming

• Kits with very present room mics (Back in Black is famous for its drum sound that is both wide and dry).
• When programming: snare velocity 115–127 with small variations (±5), alternating hi-hat 100/80, snare 5–10 ms behind.

Typical mistakes

• Too many fills; double kick where it is not needed; "metal" drums with click and triggers; hi-hat always closed.

Bass

Sound

Precision Bass with pick or fingers, Ampeg or Marshall amp; round sound with a bit of grit in the mids (600 Hz–1 kHz).

Role and notes

• Eighth notes on the root under the riff (Cliff Williams is the model: absolute simplicity).
• Doubling the riff an octave below in Deep Purple/Led Zeppelin-style songs.
• Short linking passages (2–3 note walk-ups) only before the choruses.

Relationship with the kick

Long, full notes that "fill" between one kick hit and the next; attack aligned with the kick on 1 and 3. The bass occupies the 70–120 Hz range, the kick 50–70 Hz.

Examples

• AC/DC — Back in Black; Deep Purple — Highway Star; Guns N' Roses — It's So Easy (Duff McKagan with pick and a bright sound).

Harmonic instruments

Guitars

• Rhythm: power chords, open chords with open strings, riffs with rests and accents. Malcolm Young (AC/DC) is the model: Gretsch with little gain and lots of volume, open chords played hard.
• Lead: Les Paul or superstrat (Van Halen, from the 1980s), solos with bending, vibrato, tapping (Eddie Van Halen), whammy bar.
• Amps: Marshall Plexi/JMP/JCM800 at full volume; for the 1980s modified amps and the first high-gain amps.
• Tuning: standard or a half step down (Van Halen, Guns N' Roses, Jimi Hendrix play in Eb: Eb Ab Db Gb Bb Eb).
• Layering: two guitarists, one per side; in the studio each doubles his own part.

Keyboards

• Distorted Hammond (Deep Purple, Uriah Heep), 1980s synth brass (Van Halen — Jump with Oberheim), piano in ballads.

Voicings

• Full chords (with the third) used sparingly in the distorted rhythm: the major third with a lot of gain creates beating. Better power chords or open chords with little gain.

Melody and vocals

Vocals

• High, raspy voices: Bon Scott and Brian Johnson (AC/DC), Ian Gillan, Robert Plant, Steven Tyler, David Lee Roth, Axl Rose (very wide range, from baritone to high screams), Paul Rodgers (more soulful).
• Pentatonic, rhythmic melodies, often "spoken" in the verses and screamed in the choruses.

Backing vocals

• Gang vocals in the choruses (AC/DC, Kiss): 3–6 male voices in unison or in fifths, heavily compressed.
• Third harmonies and countermelodies in power ballads.

Effects

• Plate or room reverb, slapback delay; heavily compressed and saturated vocals to sit above the guitars.

Instruments

• Two electric guitars (humbuckers, Marshall amps), acoustic guitar in ballads.
• Electric bass with pick or fingers.
• Acoustic drum kit (22"–24" kick, metal snare, hi-hat, 2 crashes, ride, 2–3 toms).
• Lead vocals and group backing vocals.
• Hammond organ, piano, 1980s synths (optional).

Drum patterns

Synths and sounds

• B-3 V — Distorted organ: Jon Lord-style: full drawbars, Leslie fast, high amp drive, chords in fifths in unison with the riff.
• OP-Xa V — 1980s synth brass: The synth from Jump (Van Halen, Oberheim OB-Xa): doubled, slightly detuned saws, open filter with a short envelope, big chords in close position.
• Piano V — Piano: Boogie and power ballads: grand piano, compression, and a cut at 200 Hz.
• Jup-8 V — Power ballad pads: Soft, wide pads under clean guitars with chorus; attack 200–400 ms, release 1–2 s.
• Mini V — Lead synth: 1980s-style monophonic leads for intros and keyboard solos.

Song structure

Form (3:30–5:00)

Arrangement

• The riff is the protagonist: it comes in alone and returns between sections.
• The crescendo comes from the backing vocals and the cymbals, not from new instruments.

Mixing and mastering

Sonic goal

Powerful but open: "big" guitars with pronounced mids, drums with lots of room, aggressive vocals above everything. Less saturated and less scooped than metal. References: AC/DC — Back in Black (1980), Guns N' Roses — Appetite for Destruction (1987), Van Halen — Van Halen (1978).

Kick

• EQ: HP 30 Hz, +3 dB at 60–70 Hz, −4 dB at 350 Hz (Q 2), +2/+3 dB at 3 kHz.
• Compression: 4:1, attack 15–25 ms, release 80 ms, 3–4 dB.
• Level: a bit below the snare.

Snare

• EQ: +2/+3 dB at 200 Hz, −3 dB at 800 Hz if "boxy", +3 dB at 5 kHz.
• 1176 compression: attack 5 ms, release 100 ms, 4–6 dB; parallel at 30% heavily compressed.
• Reverb: room 0.8–1.2 s or plate 1.5 s, pre-delay 10–20 ms.

Room and overheads

• Very present, compressed room mics (up to 10 dB of reduction in the parallel).
• Overheads HP 200 Hz, shelf +1 dB at 10 kHz.
• Drum bus: 4:1, attack 30 ms, release auto, 3 dB; tape saturation.

Bass

• EQ: HP 35 Hz; +2 dB at 80 Hz; −2 dB at 250 Hz; +2/+3 dB at 800 Hz–1 kHz (pick grit).
• 1176 4:1 + LA-2A compression, 6–8 dB total.
• Parallel drive filtered HP 300 Hz.

Guitars

• Layering: 2 rhythm parts (one per guitarist) L100/R100; if there is only one rhythm guitarist, double the part (two different takes) L100/R100. In the choruses a third track (open chords or the same part with another amp) at L60 or R60.
• EQ: HP 80–90 Hz; −2/−3 dB at 250–400 Hz; +2 dB at 1–1.5 kHz (body of the crunch); +1/+2 dB at 3 kHz; −2 dB at 6 kHz if it "fizzes"; LP 10 kHz.
• Microphones: SM57 at the edge of the cone + ribbon at 15–30 cm; amp in a room with a room microphone for the ambience.
• No compression on the rhythm; on the lead a light 2–3 dB.
• Lead: center or slightly off-axis, dotted-eighth delay (feedback 20%, filtered HP 300 Hz/LP 5 kHz, −15 dB) and plate.

Vocals

• Chain: EQ (HP 100 Hz, −3 dB 300 Hz, +3 dB 3–4 kHz) → 1176 4:1 fast (5–8 dB) → LA-2A (3 dB) → de-esser → saturation (Decapitator/Saturn 2 light).
• Space: plate 1.5 s, slapback 100–120 ms.
• Automation: raise the key words, lower the breaths.

Backing vocals and gang vocals

• Stack of 4–8 tracks, alternating L/R, heavy compression, HP 150 Hz, longer room or plate, 3–6 dB below the lead vocal.

FX

• Plate (vocals, snare), room (drums), tempo-synced delay (lead and vocal throws).

Buses and groups

• Guitar bus: compression 1–2 dB, light saturation; mix bus: 2:1 glue.

Sidechain

• Optional: dynamic EQ −2 dB at 2–4 kHz on the guitars when the voice sings.

Master

• Chain: EQ → bus compressor (attack 30 ms, 1–2 dB) → saturation → limiter.
• Target: −10/−8 LUFS integrated, short-term −8/−7 in the choruses; true peak −1 dBTP.

Common mistakes

• Too much gain: the riff turns into a hiss.
• Metal-style guitars scooped in the mids: hard rock lives between 500 Hz and 2 kHz.
• Triggered drums without ambience.

Reference tracks for the mix

• AC/DC — Back in Black (1980); Guns N' Roses — Welcome to the Jungle (1987); Van Halen — Panama (1984); Aerosmith — Walk This Way (1975); Airbourne — Runnin' Wild (2007).

Reference listening

• Deep Purple — Highway Star (1972)
• Aerosmith — Walk This Way (1975)
• AC/DC — Highway to Hell (1979)
• AC/DC — Back in Black (1980)
• Van Halen — Panama (1984)
• Guns N' Roses — Welcome to the Jungle (1987)
• Guns N' Roses — Sweet Child O' Mine (1987)
• Wolfmother — Woman (2005)