I was talking to someone the other day and she mentioned that the modulation formula she always used was simply to play ii – V – I into the new key. In other words, if moving from F to G, she would finish the song in F and then play Am – D7 – G to get into the new key.
That sounds pretty simple but here is my question: is it good enough? The answer is yes and here is why:
Modulations are about changing a tonal center in the minds of the listeners. When listening to a song, even music novices unconsciously establish a home plate in their mind which happens to be the tonic (first degree of the scale of the key). They then categorize all the other notes around home plate.
We musicians all know that the tonic is relative; there are 12 tonic possibilities because there are 12 keys. When you change keys, the tonic note changes. There is a new home plate and and all the other notes are categorized in relation to the new home plate but nothing about the music itself changes. There is still the exact same distance between the tonic and the dominant just like there is the same distance between home plate and first base regardless of the major league park you go to.
The whole point of a modulation is just to move home plate and have all the listeners move home plate with you and as it turns out, the ii – V – I progression is an effective way to move home plate. Once you play those three chords in the new key, every listener is going to be reoriented around the new tonal center.
I say this with a caveat and also a confession. The caveat is that while the ii – V – I works as a modulation, it is often going to be clumsy and is not ideal. The movement from the old key to the ii chord in the new key is often an awkward jump. That being said, my confession is that I use it too quite often in church. The reality is I am always doing modulations on the spot and I just do what is easiest.
The ii – V – I is like an adjustable wrench. You can make an adjustable wrench work for any size nut. Likewise, ii – V – I always works between any two keys. But no mechanic wants to use an adjustable wrench if they have the exact sized wrench. That is true for modulations too. Great modulations that fit a situation exactly take into account a lot of factors including the relationship between the two keys, the length the modulation needs to be, the style of the song, etc.
You don’t always need a great modulation but sometimes you need to go the extra mile. For example, I am writing a song right now that has a couple of key changes built into the tune itself. The B section jumps up a third for 4 bars and then up another third for 4 bars before returning to the original key and the A section. In that situation, I spend a lot of time on the modulations making them as smooth as possible. Certainly, a simple ii – V – I would not be appropriate.
So what I am saying is this: learn your ii – V – I progressions in every key and you will be able to modulate on the spot. That is a great start and certainly will work most of the time. You won’t win awards with it but it will get the job done. If you want to take modulations to a higher level though, you will need to work a bit harder refining a custom modulation for a specific situation.