For a long time my key choice was largely arbitrary. It was usually whatever key I started writing the song in, which was almost always C major or A minor since I had little theory and keyboard skills. However, as my songwriting and arranging skills progressed, I began to realize just how important a song’s key is. Below I want to share some important points that I take into consideration when figuring out a good key for the song I’m writing.
Featured instrument(s)
When choosing a key, one of the first things you should consider is the instrumentation. Depending on the instrument you’re writing for, certain keys will sit better on it than others. For example, sharp keys lend themselves well to guitars because they can play more chords with open strings in these keys. Wind instruments (brass and woodwinds) generally prefer flat keys because it’s easier to play in tune, and the fingerings are less awkward. When you’re writing for vocalists, most of the time the key is decided by their range. While instruments such as guitar or saxophone have a standard range, it will vary widely for voice because each person has a unique set of vocal chords that will determine whether they’re a soprano or alto, or somewhere in between.
In a case where you have multiple instruments in your arrangment that perform better in different keys, my suggestion is to pick the key that feels best on the instrument(s) being featured most. In popular music, this is typically the voice, which means you should be picking the key that feels most comfortable for whoever is singing.
If you’re writing an arrangement that features multiple instruments equally, you may have to find a compromise. For example, “Sir Duke” by Stevie Wonder shows off both Steve’s voice and the horn section. If possible, I would try finding a key that feels good for both. For example, if I were the arranger and I narrowed down my options to B major and Bb major, I would choose Bb major because a semitone usually doesn’t make a big difference for vocalists, however it will make the fingerings immensely easier for the horn players.
For my final point, if you have any transposing instruments in your arrangement (eg. Bb trumpet, Eb alto saxophone, etc.) make sure that the concert key you choose feels comfortable on those instruments as well. I’ve seen it happen where an arranger puts a song in the key of concert A major, thinking they’re being reasonable by giving the musicians only three sharps, only to forget that A major transposes to B major for trumpet and clarinet, and F# major for Eb alto and baritone saxophone. If you play any of these instruments, you’ll know that concert A isn’t a fun key to play in. Of course every musician should learn to play in these keys, but truthfully, they’re annoying keys to play in regardless of skill level.
Melody range
When you write your melodies, make sure they are in a playable range! I know I’ve been guilty of writing a melody on piano, only to discover too late that it was way too high for my vocal range. If all you’ve written so far is the melody, then changing the key may not be such a big deal. However, if you’ve already written out other parts of the arrangement such as the chord voicings or string lines for example, you’ll likely have to re-write these parts to reflect the shift to a higher or lower key. This is why it’s extremely important to find a comfortable key for whoever is performing the melody before you start writing other parts of the arrangement.
If you’re writing a melody with a wide range, it’s even more crucial that you figure out the right key before you start writing other parts of the arrangement because a wider melodic range means less room to move it up or down to other keys.
As an example, when I was in my third year of my music undergrad I had to do a recital at the end of the year showcasing my original music. I decided to perform a fun disco tune I had written several years ago, and to fill out the arrangement more, I wrote in a brass section with backgrounds and solis in the intro and bridge section. Being a trumpet player, I took care to write brass parts that were fun and comfortable to play, but didn’t pay enough attention to the lead vocalist’s part. When I took the music to the rehearsal, it quickly came to my attention that the melody was uncomfortably low for the vocalist singing the melody. It was still in her range, but she had to stretch a bit to get down there, and she got completely buried by the band.
There wasn’t an easy fix to this because the melodic range in both the vocal and brass parts was wide, meaning if I were to move the song up to a higher key, it would be too high for the brass players, and if I kept it where it was, it was too low for the vocalist. In the end, I had to find a compromise and move the key up a few steps, but it wasn’t ideal because it was still a little too low for the vocalist, and now a little too high for the brass section. If I had made sure that the melody was in a comfortable key for the vocalist first before I started writing the horn parts, I could have avoided the headache I created for myself.
To be continued…
In the second part of this post we’ll continue looking at other factors to take into consideration when choosing a key, such as chord voicings and the unique “mood” of each tonal centre, as well as the importance of choosing your key early in the songwriting process.