The experience producer can easily define the base key from a song to remix. By listening the vocal they already know where the key at (Major or Minor). Later on customize it on DAW.
For beginners, there is a simple way to achieve a base key of a song. After we define the key we can make a progression chord from it. Let say the basic theory of this using the “Bass Note”.
What on Earth is the Bass Note?
Simply says: Bass note is a note with 1 bar to 8 bar length or more depends on vocal note that make to ease the bass key from a vocal or others. Or let say its your chord mark on the song.
Usually the bass note use a long bass sound instrument that we can find on many VST instruments. The length itself follow the bars we make. For example, if we use Harmor inside the FL Studio plug in use the “simple bass” preset. If you play that preset will produce a long sound of bass. Try it inside piano roll.
To find the bass note from a song you can use this preset and practice it. This is the view of a bass note:
As you can see, that is a simple bass preset from Harmor that use to make a bass note. The position of the note depends on the note of the vocal. This only an example of 1 bar per each note from a song.
So how to find the right base key from a bass note?
1. First of all put the song into FL Studio playlist, do not forget to beatmap it (sync) with the bpm to make the song align with the tempo. So when you drop the first note right on the first part of a bar not on the ½ bar but between bar 1 to bar bar 2 and so on.
2. Make patterns for the bass note, use Harmor and choose Simple Bass preset, put it under the vocal (track 2 or 3 on the playlist). Make a long note about 1 or 2 bars on the piano roll before we place it inside playlist. To make it easy check this picture below:
3. Play the vocal (Press Space on Keyboard) and then go to the bass note pattern (Double click on pattern) listen to the bass is it match with the vocal or not. If not, try to change it to another note to make the both of the sound harmonic. This process need multiply stop and play the song in the playlist.
4. After you get the base note from the vocal find another note that match to the vocal on the next bar. For example, a song with base note on G usually follow by A, E, C, B, D, F note.
We can find a base note from a song use the bass note to define the next note of a song. And we can make a progression chord from that note.