Chord progressions, often called the “melody” give trap tracks the unique feeling. Chord progressions are often a combination of the actual chords with a simple melody line appended on top of the sustained chords.
Trap chord progressions are often relatively simple. Here are a couple of common chord progressions In the key of A minor:
How long each chord gets played plays a vital role when capturing the essence of trap. Long syncopated rhythms are the key to the bouncy feeling. This means that chords don’t change at the end of the bar (one bar is 4 beats) but somewhere in between. Here are some of the common chord durations:
Here’s a nice video covering most common trap chord progressions:
A combination of the chords and the melody line is explained here: https://www.youtube.com/watch?v=nGYRf7nFRQE
Chord playback style
In trap, chords act as the support for the key elements which are the vocals, heavy 808 bass and hi hat rolls. Having long sustained notes playing throughout the chord is often a good choice, leaving space for the other musical elements.
Arpeggio is another approach that works fine. It naturally leaves more space as a single note is playing at a time compared to stacked notes playing at the same time, consuming more headroom from the mix.
Instruments and effects
Chords are often bended in the background. Acoustic piano can be heard on many tracks. Synth strings with short attack and plucked sounds such as bells are also used a lot. Modulation effects (phaser, chorus, flanger etc.) combined with reverb helps to push back the chords to the background.
Trap has taken lots of shapes and forms but it has started from relatively simple harmonic space. Today, lots of R&B and jazz influences can be heard on trap tracks. Stay tuned for a post about writing those!