"This is a 2 channel equalizer, it's basically two 551E's stacked one above the other. There are 5 identical bands of parametric EQ each with a gain knob providing 15dB of cut or boost, a Q (bandwidth) knob with a range from .05 to 2 octaves and a frequency knob. The frequency knob covers the full spectrum in three ranges that can be selected by each bands three way switch. The available ranges are 10Hz to 200kHz, 100Hz to 2kHz and 1kHz to 20kHz. In addition to the parametric there are high and low cut filters operating at 12dB per octave in ranges from 3kHZ to 65kHZ and 260Hz to 6Hz respectively."


http://www.symetrix.co/kb/551e_552e_ds.pdf