3 Band Fixed and Selectable Equalizer
The next one up from a 2 band, is of course a 3 band. Like the 2 band, they come in two varieties, fixed and variable. This enables you to cut or boost 3 separate frequencies simultaneously. 3 band equalizers tend to have Shelving Curves for the Low and High end, with Peak/Dip Curves for the mid section.
As you can see, two of the dials control fixed frequencies at 100hz and 10khz. The remaining dial can select one of three frequencies to cut or boost.