A shelving EQ attenuates or boosts frequencies above or below a specified cutoff point. Shelving equalizers come in two different varieties: high-pass and low-pass. Low-pass shelving filters pass all frequencies below a specified cutoff frequency, while attenuating all the frequencies above the cutoff. A high-pass filter does the opposite, passing all frequencies above the specified cutoff frequency while attenuating everything below. Usually, the frequencies beyond the cutoff are rolled off, following a predetermined curve, not cut off sharply, as with a “brickwall” filter. For more information on Equalizers, please refer to this article.