Shelving EQ affects all frequencies above (or below) a hinge point; peaking EQ affects a band around a center frequency

Two fundamental EQ response shapes appear in console channel strips. A shelving equalizer boosts or cuts all frequencies above (high-shelf) or below (low-shelf) a ‘hinge’ frequency; the effect levels off to a constant amount in the shelved region. Shelving is appropriate for overall tonal balance adjustments (rolling off the low end, brightening the top). A peaking (bell) equalizer boosts or cuts a band of frequencies centered on the selected frequency; adjacent frequencies are progressively less affected, giving a bell-shaped response curve. Peaking EQ is used for surgical corrections, resonance control, and instrument tone shaping. Bass and treble tone controls are shelving types. Mid EQ controls are typically peaking types. The hinge frequency of a shelf and the center frequency of a peak are both called ‘turnover frequency’ or ‘knee frequency’ in different contexts.

Examples

Rolling off the low end of a guitar channel below 100 Hz uses a low-shelf EQ set at 100 Hz. Boosting the ‘presence’ of a vocal around 3 kHz uses a peaking EQ set at 3 kHz with moderate Q.

Assessment

A track sounds boomy and you want to reduce energy below 200 Hz without affecting 400 Hz and above. Which EQ type do you use? Now you want to add ‘punch’ at exactly 200 Hz without changing the overall low-end level — which type?