This lesson outlines the second step in dealing with the keyboard reconstruction question (ABRSM Grade 8 Music Theory).

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Using Second Inversions

The inversion of the chord is created by the bass line (lowest sounding notes). You should follow the normal conventions. Avoid second inversion chords except at the places where they are allowed which are:

  • cadential 6-4s (Ic-Va at a cadence, 6-4 falls on a strong beat)
  • passing 6-4s (bass moves by step, and the 6-4 chord falls on the middle weak beat)
  • pedal 6-4s (the 6-4 chord arises because of an ongoing pedal)
  • arpeggio 6-4s (the 6-4 chord is played in an arpeggio or broken chord pattern)

In this extract, chord IVc is used – can you work out for which of the above reasons it is acceptable?

purpose of the second inversion

In this case, it is a pedal 6-4. The repeated tonic G pedal starts in bar 8 and continues for several bars, while the harmony changes above it.

If pedals are used in the given material, do attempt to use them in your own part of the composition too.

An arpeggio 6-4 is shown here, from Mozart’s piano sonata no.16:

arpeggio 6/4

The broken chord pattern is very typical in keyboard style music. It is known as an “Alberti bass”.

Chord Ic has an unusual property. Although it contains the notes of the tonic chord, it actually sounds more like an unstable dominant chord, because of its doubled dominant note. For this reason, Ic works after chords which are normally followed by V , for example ii7 or the augmented 6th chords,. However, it is not normally simply used instead of chord V – but as well as. So, the following progressions are quite common:

  • ii(7) – Ic – Va
  • Germ/It/Fr 6th – Ic – V