The Quick-Change Blues

In C major

C7 – F7 – C7 – F7 – C7 – G7 – F7 – C7 — busier, more urgent than the basic form, around 112 BPM.

1. Bar 1 I7 C7
   C · E · G · Bb
   ▶ Hear it
2. Bar 2 IV7 F7
   F · A · C · Eb
   ▶ Hear it
3. Bar 3 I7 C7
   C · E · G · Bb
   ▶ Hear it
4. Bar 4 IV7 F7
   F · A · C · Eb
   ▶ Hear it
5. Bar 5 I7 C7
   C · E · G · Bb
   ▶ Hear it
6. Bar 6 V7 G7
   G · B · D · F
   ▶ Hear it
7. Bar 7 IV7 F7
   F · A · C · Eb
   ▶ Hear it
8. Bar 8 I7 C7
   C · E · G · Bb
   ▶ Hear it

Why it works

In the basic form the first four bars sit on the tonic, which is stable but static. Moving to IV in bar two and back in bar three introduces motion before the ear has settled, so the opening phrase becomes an arc instead of a pedal. Everything after bar four is identical — the entire difference between the two forms is one bar, which is a useful reminder of how little it takes to change a groove.

Where you'll hear it

Call it before counting in; the band needs to know which one you mean. Generally preferred at faster tempos, where four bars of tonic feels like waiting.

I7–IV7–I7–IV7–I7–V7–IV7–I7 in every key

The same progression transposed. The roman numerals never change — that is the whole point of writing progressions this way.

Related progressions

• I7–IV7–I7–V7–IV7–I7 The 12-Bar Blues