Depending on the manufacturer (and the price you pay!) you may have a Low Cut filter switch (sometimes called High Pass), where you can cut out unwanted low frequency rumble –these are usually centered around 75Hz.
This is useful to vocalists in a recording environment to reduce low frequency hum from the outside world.
Keep in mind that, vocally speaking, there’s not much going on in that area, so when it comes to mixing, you can eliminate those frequencies to avoid clutter in the mix.
In a live situation this switch helps reduce stage resonance and some of the rumble you get thrown at your mic by the bass, drums and guitars.