What kind of chord is this?

Question

the notes are G, Bb, E, G and C#

from Bach's Prelude in C No. 1 Well-Tempered Clavier

Answer 1

This arpeggio occurs in bar 12. In the previous bar (11) you've played a G major arpeggio, V in the key of C.

In bar 12, the G is maintained as a pedal and also functions as a chord tone with the other four notes to form a full diminished chord on Bb. This ambiguous harmony then resolves to D minor in bar 13, with F in the bass, making that resolution a ii6 chord.

The diminished chord substitutes for and functions as a secondary dominant.

Think of it this way: If, in bar 12, the Bb had been an A and all the rest of the notes stayed as written, you would have an A2 chord (A major dominant 7th chord, third inversion with the 7th in the bass). That chord would be the dominant of d (V of ii) which is where the diminished chord is resolved in bar 13.

At least that's my analysis.

But, in any case, the chord you've targeted is a full diminished chord since, in its most compact form, it is constructed entirely of minor thirds.

Answer 2

I don't know it in the context of the prelude, but when I play it, it sounds like a 3 chord, an E-minor diminished 7th (I'm assuming the G is in the bass, so it's an inversion).







I'm going to try to find my copy of the prelude to see if I can see it in context.

Answer 3

You need to unsramble the notes:

C# E G Bb makes for a C# 7 diminished chord.

Answer 4

Spelled that way, it's a C# diminished 7th.



But because it's a fully diminished 7th, if you respell the C# as a Db, it's also a G diminished 7th and an E diminished 7th, and if you also respell the E as an Fb, it's also a Bb diminished 7th. It's the same pitches for all of them.

Answer 5

Sounds like it could be a 3 chord that resolves. The almost 5 and 7 should resolve to create a major 3 then resolving into 1 or 5??????

Answer 6

I'ts an "E diminished 7th". Made up completely of minor 3rds.

Answer 7

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