Dead On Time

Composer: Brian May
Meter: 4/4
Key: f#-minor/ modally inflected F#-Major

Form:   Intro I-II (B'...A'AA) | Verse'(VAVA"...)| Chorus I-A-I-ext |
             | pre-verse (BBB')| Verse           | Chorus I-C-I-ext |
          | Solo I (BBBB") - II (VC'VC') - III - IV (B) | BBBBB' |
             | pre-verse' (BBBE) / thunderbolt |

This song together with "Let Me Entertain You" build the hard rocking core of the Jazz album. Half of the song is riff-driven, the other half is backed with chords. In the first half of the track we have two verse-chorus cycles intervened by a pre-verse. The second half of the track is acyclic. The pre-verse returns as the final vocal section. The arrangement is the usual, double tracked rhythm guitars (except intro II - as in "If You Can't Beat Them"), bass drums, lead vocal, harmony vocals, harmony guitars. The only exceptional feature is the final thunderbolt, "courtesy of God" as the album sleeve says.
The speedy main riff and the speedy lead vocal would suggest an unusual speedy (136bpm) quarterbeat.
The harmony is ambigous between Major and minor mode. Both main riffs ("A" and "B") are in minor pentatonic (blues) mode. The song is dominated by Major chords most of which are borrowed from f#-minor key, but the tonic (where the third is included) is also Major.

Intro I-II
The intro has two subsections the first of which consists of three seventh chords arranged for bent up guitar harmonies. The timing and relation to the homekey is not establied yet. Retrospectively seen we can that each three chords are suspended for four measures. These chord are going to close the song as well:

| A7       |
| bIII     |

| D7       |
| bVI      |

| B7       |
| IV       |

Beside the harmony guitars cymbals are played, and the bass work is changing chord by chord. First chord - single note, second chord - bluesy runs in fast triplets, third chord - single note sliding up an octave.
The second subsection of the intro reckless riff-work in solo (no double tracking, no drums and bass) which combines both main riffs "B" and "A" respectively.
The riffs are in minor (blues) mode. The "A" riff is repeated twice already scored for full ensemble. The bass plays a different riff in minor pentatonic mode.

The verse starts with two repeated vocal phrases both followed by the "A" riff. The lead vocal is minor mode pentatonic. The A chords behind the vocal phrases are ornamented with the D/A lick.  

 /| A   | -   | -   | -   |
 || bIII| -   | -   | -   |
 | A-riff:
 || F#1... | E1... | F#1...| C#1... |
 \\| 1st    | b7th  | 1st   | 5th    |
In the second half of the section we have three phrases AAA' (2+2+4). The lead vocal adds suspended 4th to the B7 chords scored for guitar harmonies. The final subphrase is doubled by the guitar in descending almost pentatatonic

The second verse adds lead guitar fills to the instrumental phrases. The rhythm guitar mixed to right plays "C"-riff instead of "A" here.
The last phrase is stripped down to vocals and machine gun-like combination of snare drum and rhythm guitar in 3+3+2 patterned grouping, more precisely:

/-------- 2x-------\\
| B7(sus4) | F#5   |
| IV       | I     |
| B7(sus4)| -    | -    | -    |
| IV      | -    | -    | -    |

1 2 3 4 1 2 3 4 1
****  ****  ****v

The chorus grows out directly from the end of the Verse. We have three vocal phrases the first two intervened by an instrumental phrase (A I A'A" 4+4+6). The first two measures with the title phrase of the vocal phrases are harmonised (see also "White Man").

| A   | E    | D    | B A   |
| bIII| bVI  | bVII |IV bIII|

The first phrase is followed by the "A" riff. In the second chorus this riff is replaced with the syncopated "C" riff featuring fourth powerchords. It is played just once here as the following phrase is replaced by a powerfull drum roll.

| A   | E   | D    | B Bb  |
| bIII| bVI | bVII |IV bIII|
| A   | E   | D   | B   | F#  | -   |
| bIII| bVI | bVI | IV  | I   | -   |

Before the second verse and outro we have a hard to determine section. It is dominated by the title words, but without the chorus flavor. The backing track is riff dominated (BBB') played in palm muted mode. The vocals jump an octave higher for the climactic third phrase.

/------------------- 2x ------------------\\
| E1 F#1    | -      | A1 B1    | A1 F#1  |
|b7th 1st   | -      |b3rd 4th  |b3rd 1st |
| E1 F#1    | -      | A1 B1    | -       | -      | Bm7    |
|b7th 1st   | -      |b3rd 4th  |         |        | iv     |

The closing subphrase is sung in harmony and enters on the 4th beat of last but one measure.

4 1 2 3 4 1...
*   * ** 

The Pre-verse is the closing section of the song. Note how the bass enters for the second phrase preparing the climactic third phrase, which this time is not altered compared to the first two except the higher vocals.
We have a final phrase reprising the intro chords without sevenths and using 3+3+6 syncopation before the thunderbolt hitting in. It was recorded before the Montreaux sudio and they used in for introducing live shows during the Jazz tour.

3+3+6 = three bars
| A   D   B      |... F#7   |
|bIII bVI IV     |...       |

The fermata ending with added seventh which is a clicheized gambit of rock/blues music.

The solo section has more subsetions. The first one stars with one phrase "B"-type riffing which is carried forward by the rhythm guitars. In the second phrase starts the speedy solo in 1/8 beats with lots of pulled off and hammered on notes mostly along the f# minor scale.
This speedy part is backed by further three "B"-type riff the last of which is altered and extended to six bars.

The second subsection of the solo uses the harmonic texture of the verse (VAVA). The solo itself switches to a canon-like harmony mode that moves exclusively along the B triad. The "A" phrases this time are backed with the "C" riff that we have ran into already in the second chorus.

From here the harmony is rising from bIII until the tonic in chromatic steps in the second phrase of the subsection. Along the chromatic ascent the lead guitar repeats the same fill each time transposed up.

| A   | -   | B   | -   |
|bIII | -   | IV  | -   |

| D   | D#  | E   | F   | | bVI      chromatic    |

when we finally reach the tonic the guitars play the "B" riff harmonised with triplestops on the treble frets.

| F#  | -   | B   | F#  |
| I   | -   | IV  | I   |

Following this the "B" riff is repeated four and hal times in the original form while Mercury singing along some semi-improvised phrases using 3+3+2 syncopation at "leaves you...".
In the final incarnation of the riff the second half of the phrase is segued into a guitar harmony with 3+3+3+3+4 grouping. It is repeated with seventh degree added and an extra measure of drums preparing the next section (pre-verse).

| B  | -  | -  | -   |
| B7 | -  | -  | -   | drums |