To add a bass line to your song, first figure out the key signature of the passage, and then apply a phrase of notes based on an applicable scale while at the same time thinking about how you will execute dynamics, rhythm, phrasing, and most of all, the feeling of the song. So how does one go about adding a bass guitar line to a song anyway? In fact, this is one of the reasons why older recordings tend to sound tinny – they lack low-end. It’s hard to say that a song without low-end frequencies is a song at all. It brings richness and fullness to music that would otherwise be thin and tinny.īy adding bass to a song, you instantly change its dynamics and feeling. Bass is a beautiful, dynamic instrument that pulls melody and rhythm together to fortify the low-end and the feeling of the musical piece, whatever it may be.