There are two general types of analog equalizers
Passive
Active
There are two common types of filters in today's EQ
Fixed Bandwidth
Quality Factor
An EQ filter that carries a signal to a rise or dip and then levels off is called a 700HZ filter
A High Pasd sharply reduces signals at extreme frequencies.
When a high pass filter and a low pass filter are combined, we have what is known as a Band pass filter.
When parametric equalizer is adjusted so that only a narrow bandwidth is chosen and the cut is set to fill, it is called a Notch Filter.