When working on a song with multiple instruments, often you have to think about which parts will be played by each instrument. With larger productions, you’ll tend to have more instruments than parts. In these cases, you’ll need to think about when two different instrument sounds should be combined, and when they should be kept separate. When combining the sounds of two instruments, the effect is of a single sound that is a composite of both instruments.
How to separate
Separating instruments can be achieved in a variety of ways:
- Different register (pitch range)
- Different rhythms
- Different tonality (notes in the scale)
- Different volume
- Different sound character
- Different space (panning, depth)
For best effect, you should separate instruments using several of the above techniques.
How to combine
Quite simply, the techniques for combining instruments are the exact opposite to those for separating them:
- Similar register (pitch range)
- Similar rhythms
- Similar tonality (notes in the scale)
- Similar volume
- Similar sound character
- Similar space (panning, depth)
And again, for best effect, you should use several of the above techniques when combining instruments.
Of course, simply knowing how to separate or combine sounds is just part if the story – you must also know when to do it. When should you make two instruments more separate from each other? When should you try to combine them?
When to separate
You’ll get the best results in separating instruments when the parts played by those instruments are already quite different. The best way to determine this is to think about the function each part has – what it’s contributing to the song or the mix.
For example, you might have two melodic or harmonic parts in your song. You would be better off separating them if one is playing long slow notes and is only heard during the climaxes of the song, and the other part is playing small repeated arpeggios throughout most of the song. Even if both parts are played with similar instruments, in the same pitch range and with the same tonality, the two parts are definitely performing different functions in the song. To further separate them, consider changing the instrument or sonic character, the pitch range, or perhaps the depth of one or both parts. This will bring more clarity to the overall song. In other words – you hear them as different parts, so make them more different.
When to combine
The opposite is true when deciding when to combine instruments. If two parts are performing a similar function in the song, they’re probably good candidates for being combined.
For example, you might have two parts that are playing short staccato rhythms (think of an arpeggio with gaps between the notes). The two parts might be played by different instruments, with different rhythms and different pan positions. Even still, they are both performing the same function in the song. To combine them, consider making the pitch ranges, pan position, or sonic character more similar. This will make your song more cohesive and and focussed. In other words – you hear them as similar parts, so make them more similar.
In applying these ideas, you’ll bring more focus and clarity to your music.