Equalizers work by running an audio signal through a series of filters which can be adjusted to increase or decrease the volume of a particular frequency. Equalizers (commonly referred to as "EQ") can be used to fine-tune the sound of a particular instrument when being recorded or may be used on a full mix to add more presence to a mix or remove some of the upper mid-range frequencies which might have a tendency to sound harsh or "nasal". An equalizer may also be used to remove the inaudible frequencies in the 20 to 40 Hz range from being amplified. Musician's Friend has over 70 equalizers to choose from including Behringer Equalizers and dbx Equalizers. As with everything we sell, all our equalizers are supported by our price & satisfaction guarantees and free standard shipping applies to all orders except heavy items.