Changing Key using Diminished Chords

Hi,

Thanks to Corbind for suggesting this.

Here is a worked example to listen to:

http://mp3.moosoft.net/alan_green/Toothbrush.MP3

I have no shame, it's one of my own songs.

The song starts off in D Major - there's a short intro, two verses and a refrain. Then there's a guitar solo. Then comes the nifty key-change bit.

I start by playing the tonic chord - in this case the D Major - the I chord.

Then I play a I#dim7 - D#dim7. The notes in this chord are D#, F#, A and C - all a minor third apart. If you look at the A and the D#, and the F# and the C, you'll notice that you have two tritones. The D# is three whole tones from the A, and the C# is three whole tones from the F#. The impact of this chord is that it is hugely dissonant and is looking for somewhere to resolve. Because the chord uses the same notes whether you're playing D#dim7, Adim7, Cdim7 or F#dim7, you're suddenly not rooted to any given key - so you can see that the resolution we're trying to achieve could go anywhere.

Pick a target Key - I picked F

One of the most common sequences you'll come across is ii-V-I - check out Darrin Koltow's work if you don't believe me. http://www.maximummusician.com is the place to go.

So, I want to resolve to my new key, and the next chord I play is Gm - the ii chord in the key of F.

This leaves me with the V-I to complete - and this will be recognised by classical theorists as a Perfect Cadence. In F, the V chord is C - it's a dominant chord, and therefore wants to resolve to.......

F - which is the tonic - the I chord - of my new key. If you listen, you'll notice that as I first play the F chord, the next verse can come straight in because I use the I chord in the first bar of the verse.

And there you have it - I start in D, and come out in F using I - I#dim7 - ii - V - I where the ii is the first chord in the new key.

Best,

Alan :-)