A low-cut filter, also known as a high-pass, attenuates the lower end of the spectrum. A practical example of its use is the removal of microphone stand noise that transmits stage resonance. Another example: vocals are explosive, and one might think the problem can be resolved with an audio compressor. Well, no: you have to trim the signal and work on the dynamics afterward!

Classic equalizers from the ’70s and ’80s were often Baxandall-type. These aren’t selective in removing unwanted sounds. Such a filter acts progressively by attenuating or enhancing an entire frequency band.

Low-Cut Filter project main

At that time, the low-cut filter was only found in high-end mixing consoles. It wasn’t until the ’90s that it appeared in low-cost mixers such as the Soundcraft Folio, Mackie, and many others. For my part, I had installed this circuit in a mixer that didn’t have one, but had enough space to accommodate a small PCB and a switch. The solution for inserting this module at the mic preamp output without...