You’re a songwriter/producer and you want to know how to write sexy bass lines? Here’s 3 pro tips:
1. Monophonic vs. Polyphonic (Low Interval Limits)
Keep your bass parts monophonic (one note at a time). Do not write chords for the bass guitar, even if it’s just octaves or fifths.
The reason why you don’t want to write polyphonic chords for your bass player is that the bass plays in a very low range. And the lower you get, the muddier the sound. In fact, each interval has an official “Low Interval Limit” at which point it stops sounding good. For the third for example, this low interval limit is around d below middle c.
The more complex the interval (= the higher in the overtone series), the higher the low interval limit. In other words, simple intervals like the octave or fifth can be played very low, whereas a seventh should be played fairly high in order for it to still sound good.
As a general rule, do not ever write any intervals lower than f below middle c. This of course with the exception of the fifth and octave – those can be written pretty much as low as you want.
Still, it is rather uncommon to let the bass play chords, even if its intervals are played above their respective low interval limits.
If you want an octave or fifth sound, let your bass player ALTERNATE your desired note with the root note. This way, a 4/4 bar of 1-1-1-1 becomes 1-8-1-8 (alternating with octave, often heard in Funk) or 1-5-1-5 (often heard in Latin music).
Besides the octave and fifth, there are few notes that lend themselves to this approach, again because of their low interval limits. That means that even if you don’t play both notes at the same time, when you play a third in the bass make sure it’s above its low interval limit.
If you want to let your bass player play chords or intervals, let them play higher up on the neck and on the higher strings. This way, they stay away from their low interval limits and the intervals sound strong and clear.
(Want to learn how to write for drums as well? Check this)
2. Which Notes Do I Play?
In 99% of your songs, let the bass play root notes. It’s the strongest note you can play and it gives a warm sense of clarity to each chord.
Here’s a couple of examples when you could decide NOT to use the root note:
- Pedals. Listen to the bass in the chorus of Katy Perry’s “I Kissed A Girl” – the bass doesn’t move. This is what’s known as a bass pedal (the term comes from church organs, where the bass is played with the feet). Pedals were very “in” in 80’s Rock music, but we still hear them every now and then. What usually happens is that the bass stays on the tonic of the song while the rest of the band moves through different chords. Very rarely does the bass play any other note, but you can experiment with the fifth as well.
- Voice Leading. This has a rather classical sound, but instead of jumping around with the bass, you could decide to move it stepwise to another chord tone in order to create a step-wise line. For example, in a ii-V-I in C (Dm – G – C), instead of writing d – g – c (root – root – root), you could write a – b – c (fifth – third – root).
- Tension. Not playing the root note can create quite a lot of tension. Make sure you’re not going below low interval limits, because anything harmonically challenging should at least sound clearly. But watch out: Playing anything but the root, third or fifth of the chord changes its function and what you’re left with is a completely new chord. For example, if your keyboarder plays a C and you play the a, you’re left with an Amin7 (a – c – e – g).
In Rock, always phrase with the guitars. When the guitars start, you start, when the guitars stop, you stop. Simple.
If you don’t have any guitars in your song, or if the guitars are not playing rhythmically, the interaction between kick drum and bass guitar becomes vitally important. I will not go into this here as this concept is really rather complex but if you want to learn more about this, there is a long, long section just about this very subject in this masterclass here (and it’s easily my favorite part of the program).
- Do you regularly check your Low Interval Limits?
- What other examples can you think of where you don’t let the bass guitar play the root note?