31 Bands Graphic Equalizer

The graphic equalizer shall be stereo (2 channels). Each channel shall consist of 31 bands centered on standard ISO frequencies at intervals of 1/3 octave and covering a frequency range of 20Hz to 20kHz. Individual bands shall be activated by linear slide faders with a 45mm travel, metal actuator shafts and a tactile center detent. The range of equalization per band shall be either ±6dB or ±15dB selected via a 2-position switch.

    The equalizer shall have a gain of unity with all sliders centered, and shall have a maximum in/out level of +22dBu. Frequency response shall be ±.25dB 10Hz to20kHz. Hum and noise shall be at least -92dBu and SMPTE intermodulation distortion or THD shall be less than .01% at full output. Input impedance shall be 20k ohm balanced, 10k ohm unbalanced. Output impedance shall be 200 ohm. Inputs and outputs shall be active (transformerless) balanced type on both XLR, 1/4" phone jacks and barrier strip terminals.


    Individual filters shall be Wein-bridge type and connected in a summing circuit optimized for minimum filter interaction and constant bandwidth at any slider setting. Boost and cut characteristics shall be fully symmetrical, with the filter being electrically removed from the circuit in the center (flat) position. Individual filters shall be accurate to within 3% of indicated center frequency and shall be non-adjustable to insure long term accuracy.


    The equalizer shall also include an 18dB per octave high pass filter tunable from 8Hz to 200Hz, equipped with a bypass switch. A 2 color bar-graph meter shall be employed to show overall output level and an LED indicator shall show overload conditions. Input gain shall be adjustable over -infinity to +6dB, and an overall EQ bypass switch shall be included.

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