High-Pass And Low-Pass Filters

High-Pass And Low-Pass Filters

What do those switches with the "bent line" icons do?

by Phil O'Keefe

You've probably seen them in a few different places - those switches with the "bent line" graphics on microphones, mixing boards, mic preamps and EQ plugins - but what are those switches for, and when should you use them? Well that's exactly what we're going to cover in this article.

What we're talking about here are filters, which are a type of equalizer. These are designed to change the frequency response of the signal passing through them.

A switch or button for a high-pass filter (often abbreviated as HPF) will usually be indicated by a symbol such as one of the ones shown in Figure 1.

Do you have questions about high-pass and low-pass filters, or comments about this article? Then please join the discussion in this thread in Phil's Studio Trenches forum right here on Harmony Central!

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Phil O'Keefe is a multi-instrumentalist, recording engineer / producer and the Senior Editor of Harmony Central. He has engineered, produced and performed on countless recording sessions in a diverse range of styles, with artists such as Alien Ant Farm, Jules Day, Voodoo Glow Skulls, John McGill, Michael Knott and Alexa's Wish. He is a former featured monthly columnist for EQ magazine, and his articles and product reviews have also appeared in Keyboard, Electronic Musician and Guitar Player magazines.