What are some techniques for changing scale convincingly?

Question

I am having trouble changing scales smoothly when composing, it always seems that the two parts are not connected and the change is sudden.

I want to know some techniques so I can do that convincingly and smoothly.

Some things I tried are the following.

First, I tried just switching a chord a third apart from the last chord of the original scale, for example lest say I am in C minor and I play cGcA# then to switch to D# minor I would play d#, but this seems toobsudden of a change to me.

Second, I tried using rest between the two scales so the listener will forget the previous scale, but this doesn't always give me a result I want.

What other techniques for changing scale are there?

Answer 1

Firstly, don't conflate or confuse between scales and keys. The two are connected, but generally we write in a key, and use the scale notes basically from that key diatonically - but often other notes tend to creep in too, so it's not made from a scale any more.

Several ways work and are used regularly. Moving to the key either side of the existing one in the circle of fifths is subtle. Say we're in key C, moving to key F or key G involves changing only one note diatonically, so the other six still get main use.

Using the parallel key works well, because there's still the root note, or home. So, C major into C minor - or vice versa.

On the same tack, going modal, using the same root has been known to do the job. So, C major into C Mixolydian, etc.

As above, using the relative key is good, as most original notes are retained. So, C major into A minor.

Introducing diminished harmonies (which are usually not 'in scale'!!) is also a time-honoured device. Because diminished chords are not major nor minor, they have that certain uncertainty about where they might lead - a perfect opportunity to escape from the existing key.

There's also the 'truck driver's gear change - simply put, suddenly (or subtly with the dominant chord for the new key) changing up a semitone or even a tone. So, C major into C♯ major, or C major into D major.

There are several more ideas - why not study some works, and even pop songs, to find out other ideas?

Answer 2

It isn't clear what you mean by "convincingly" or "smoothly" change scales.

It sounds like you're using "scale" to mean "key." The technical word for changing keys is modulation.

The typical thing to do which is covered in most basic harmony textbooks is change to a related key, the dominant, subdominant, or relative. Or, change mode to the parallel key.

The idea is the changes either differ by zero or only one sharp or flat in the key signatures, or with a parallel change of mode, the tonic stays the same. The similarity of tones between the keys makes them "related."

C minor, three flats, and D sharp minor, which is more easily called E flat minor, has six flats. That's a difference of three flats and so is called a distant key.

You can apply the same principle to scales. Scales that have more common tones will sound similar. For example, C major and G major have six out of seven common tones. The difference is the F natural versus F sharp. Changing between two such closely related scale will be less noticeable than two scales that differ by many tones.

Keep in mind there are times when a composer wants to deliberately change key suddenly, and make the change very noticeable. That is called direct modulation. You could use it for surprise, a sudden change in "energy", to express an extreme emotion, etc.