Zähl EQ1, Parametric 4-Band Stereo EQ, API 500 format, Amplification range for all bands between +/- 5 dB and +/- 15 dB switchable, Treble: Frequency adjustable from 2 - 20 kHz, characteristic switchable Shelf / Bell, Mid-range: fully parametric, frequency adjustable from 600 Hz to 6 kHz, frequency range switchable to 1.8 - 18 kHz, Mid-range: fully parametric, frequency adjustable between 200 Hz - 2 kHz, frequency range switchable to 40 - 400 Hz, Depths: Frequency adjustable from 30 - 300 Hz, characteristic switchable Shelf / Bell, High pass filter adjustable from 25 to 250 Hz, Input impedance:> 30 kOhm, Output impedance: 50 ohms, Maximum level: +26 dBu, Reference level: +6 dBu / + 4 dBu, Power supply: +/- 15-17V, <250mA@+*Note:* Requires 500 rack with at least 2 empty slots.