Reducing one frequency in song

1. How do I stop my frequencies from clashing?
2. What is the lowest frequency in a song?

How do I stop my frequencies from clashing?

Use instrument selection, level balance, EQ, panning and side-chain compression to reduce conflicting frequencies in your next mix.

What is the lowest frequency in a song?

Sub-Bass: 20 to 60 Hz

The sub-bass range is the lowest audible frequency range and home to the deepest instruments in the mix.