EQ or Filters

EQ stands for equalization, but really it refers to filtering. Filters can lessen or remove certain frequencies vs. others. They are used to a very large extent throughout the guitar signal, with tone knobs, stomp pedals, amps, mixing boards, and DAW's all performing some filtering.

Cutting vs. Boosting

Good advice is to try to use EQ to cut frequencies instead of boosting. Filters cannot add frequencies - what they do to boost is to cut all other frequencies, then amplify the resulting signal. All filters reduce the signal level relative to the noise floor, reducing SNR. Boosting a small range of frequencies is actually cutting most frequencies and thus dramatically raising the noise level.

Also, the way we perceive volume we often mistake volume for SNR. In other words, we tend to prefer a louder signal over an identical but softer one. By boosting with EQ, you increase the volume while decreasing SNR. You may initially perceive this as an improvement, but it may sound better to simply turn up the volume without filtering. By restricting yourself to cutting, you do not run this risk.

By boosting with EQ you also run into the risk of clipping the signal, even subtly.

Digital EQ

Digital EQ's use phase-shifting to perform the task of analog filters. While this gives more control over exactly how you EQ the sound, it can also lead to artifacts such as transient-smearing, depending on exactly how the EQ operates.

Common EQ's

• Band-Pass/Band-Stop
• Low-Pass/High-Pass
• High/Low-Shelf
• Parametric EQ
• Graphic EQ
• Notch EQ

Common Guitar EQ

Most amps have Bass, Mids, Treble, and Presence controls, or BMTP. The exact ranges for each control depend on the amp, and often they actually interact with each other, shifting the shape and center frequency of

Common EQ Techniques

Scoop Mids Low Pass High Pass