The Coleman Audio CA500EQ is a 4-band stereoequalizer.
 
The inputs & outputs are balanced on XLR connectors. There is an input level control so you can adjust the audio signal before equalizing to help prevent clipping, and an output level control to read just the gain of the signal with equalization.
 
The EQ in switch turns the entire equalizer on or off. The stereo/mono switch allows the CA500 to become a mono EQ unit. The audio passes through the left channel first and then through the right channel providing more EQ options.
 
The high frequencies (8 kHz, 10 kHz, 12 kHz and 16 kHz) can be switched between shelving or peak EQ with 10 db of boost or cut in 2 db discrete steps. The low frequencies (30 Hz, 60 Hz, 100 Hz, and 150 Hz) are shelving EQ with 10 db of boost or cut in 2 db discrete steps. The two mid bands are peak equalizers with frequencies overlapping by 1/4 octave and have up to 14 db of boost or cut in 2 db discrete steps.
 
The circuits are designed to musical scales, not to mathematical relationships and the variable "Q" circuits maintain the tonal balanceas the amplitude is adjusted.

The Features
- Level and frequency settings use stepped switches
- Two Balanced stereo inputs & outputs on XLR's
- Hard bypass & phase reverse on each channel
- Input & output trims for level control
- Low frequency shelving at 30 Hz, 60 Hz, 100 Hz & 150 Hz
- Hi frequency can select peak or shelf EQ
- Mid 1 & Mid 2 are peak EQ with 14 db of boost or cut in 2 db steps
- Independent Hi-pass filter cuts 18 db per octave 30 Hz to 300 Hz