Led Zeppelin

A debut recorded in 36 hours with the band's own money. It mixes blues covers with originals, but the band's grammar — the contrast between sheer volume and silence — is already fully formed.

• In "Good Times Bad Times," the opening track chosen as the representative song, Bonham kicks the bass drum in rapid bursts of three with a single pedal (triplet strokes). Isolate the thumping before and after the chorus and you'll understand why the drummers of the day were astonished.
• Page has said he recorded the guitar solo on the same song by plugging his guitar into an organ amplifier with a rotating speaker (a Leslie speaker). Listen for the texture of the sound, swaying as if in waves.
• At this time Page played the Telecaster he had received from Jeff Beck through a small Supro amplifier. The torn, thick tone (distortion) he got without a big amp came from pushing the small one to its limit.
• In the middle section of "Dazed and Confused" you hear the howling sound Page drew by scraping the guitar strings with a violin bow. Onstage this passage often stretched to nearly 20 minutes.
• "Babe I'm Gonna Leave You" alternates the quiet arpeggios of an acoustic guitar (playing a chord one note at a time) with eruptions of electric guitar. It is a model of how light and shade trade places within a single song.

The opening track of Led Zeppelin II, completed while moving from studio to studio in the gaps between tours. It was never released as a single in Britain, but it reached No. 4 in America and thrust the band into the mainstream.

• The short, insistent guitar riff of the intro (a short phrase repeated throughout a song) was played on the Gibson Les Paul Page acquired in 1969. Jones's bass doubles the same figure underneath, making the riff sound heavier still.
• In the long break midway through, an electronic instrument sounded by hand gestures near an antenna, without being touched (the theremin), mingles with Bonham's percussion. Page and engineer Eddie Kramer turned the knobs during mixing to swirl the sound from side to side, so it's best heard on headphones.
• Just before Plant cries out again at the end of the break, there is an eerie effect in which the echo of his voice arrives before the voice itself. It is the backward echo technique Page loved to use.
• Plant's vocal pushes the cries and moans of blues singers to the extreme. Kramer recalled that rather than erasing a voice from an earlier take that had faintly bled through, they kept it as an effect; in the quiet passages it sounds like a voice drifting in the distance.

An album holding both the songs written on acoustic guitar in a Welsh cottage and impressions of Iceland. It revealed for the first time that the band of the roar also had a quiet face.

• "Since I've Been Loving You," chosen as the representative song, is a slow minor-key blues. Jones played the Hammond organ while working the bass pedals with his feet, handling the bass line on his own as well.
• In the quiet passages of the same song you can clearly hear Bonham's bass drum pedal squeaking. It is a trace of recording almost live, and Page later said he was surprised to discover the sound during remastering.
• The guitar solo near the end is often cited as the most emotionally charged of Page's playing. Listen for the way he pushes short notes upward (bending) and makes them weep.
• On the record's second side, "Gallows Pole," "Tangerine" and "That's the Way" center on acoustic guitar·mandolin·banjo. Heard alongside "Immigrant Song" on side one, they bring the record's two faces into sharp relief.

The centerpiece of the untitled fourth album. Though it was never released as a single, it became the most requested song on 1970s radio.

• The opening is a duet of acoustic guitar and recorders. Jones layered the recorders in several overdubs, and this is where the medieval atmosphere comes from.
• The song builds as each section adds one more instrument. The electric 12-string guitar comes in, and Bonham's drums don't appear until well past the 4-minute mark. Listen while waiting for that moment, and the structure comes into view.
• Page has said he played the late guitar solo on a Telecaster given to him by Jeff Beck. Once the solo ends, the tempo noticeably quickens and Plant climbs to the very top of his range.
• After the explosion, Plant's voice alone remains to close the song. Onstage, Page played it on a Gibson double-neck guitar with two necks, one 6-string and one 12-string.

A remaking, in the stairwell hall of Headley Grange, of the Mississippi flood blues recorded in 1929 by Memphis Minnie and Kansas Joe McCoy.

• Bonham's drums, audible from the first bar, were set up in the stairwell hall of a manor house and captured by two microphones hung from the floor above. Engineer Andy Johns's recording later became one of the drum sounds most often sampled by hip-hop musicians.
• Plant's harmonica carries an effect in which the echo sounds before the original note (backward echo). That is where the sense of sound spreading thick and sticky, like a swamp, comes from.
• Page has said he adjusted the tape speed on some of the recordings to drag the sound down and make it heavier. That is why the whole song sounds slower and more ponderous than its original tempo.
• At the end of the song, which runs over 7 minutes, the many sounds swirl from left to right and blur. Listen on headphones and you can hear how spatial the mix is.

Plant's lyrics, born on a Moroccan desert road, met Page's alternate tuning to become the summit of Physical Graffiti. At the 2007 O2 concert, too, it drew the biggest roar.

• Page used an alternate tuning that retunes the strings, from the lowest up, to D·A·D·G·A·D (DADGAD). Notes from the unfretted strings keep ringing underneath, creating a hazy resonance.
• The guitar riff cycles in units of three beats, while Bonham's drums walk steadily in four. As the two cycles slip apart and lock back together, they create a tension that seems to keep pushing forward.
• The strings and brass in the refrain were arranged by Jones and recorded with session players. Listen separately for the string line that rises and falls with the guitar riff.
• Bonham's drums sound as though they carry an effect that slightly twists the sound so it undulates (phaser). Though the tempo barely changes over 8 and a half minutes, shifts in texture like this are why it never grows dull.

The opening track of Presence, made in 18 days in Munich in late 1975, when touring was blocked and the future uncertain. Page is said to count it among the work he is proudest of.

• In a single long session at the end of recording, Page layered guitar upon guitar (overdubbing). He called it a guitar orchestra. Listen for the passages where different guitar lines overlap across the left and right channels.
• Like a galloping horse, Bonham drives the same rhythm for more than 10 minutes. The relentless toms and cymbals are the engine of the whole song.
• Jones played an 8-string bass, with eight strings, adding a metallic doubled ring to the bass sound. Listen for the glittering upper notes above the low end and you will hear it.
• A lineup of guitar, bass, drums and voice alone, with almost no keyboards. Heard alongside the album's other songs, it lets you feel the sound of the band at its rawest.