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The Low Cut or High Pass Filter Switch

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.

Back To VC’s Brief Guide To The Mixing Board