The sound of any playback system - be it a home stereo or a huge sound reinforcement system - will vary greatly when used in different rooms. This is because each room has its own acoustic properties. A graphic equalizer can compensate for this difference.

YAMAHA GQ1031

• 31 Band (1/3 octave) at 20hz, 25hz, 31.5hz, 40hz, 50hz, 63hz, 80hz, 100hz, 125hz, 160hz, 200hz, 250hz, 315hz, 400hz, 500hz, 630hz, 800hz, 1khz, 1.25khz, 1.6khz, 2khz, 2.5khz, 3.15khz, 4khz, 5khz, 6.3khz, 8khz, 10khz, 12.5khz, 16khz, 20khz
• Range of Boost / Cut 0 ~ +12db / 0 ~ +12db

 EV EQ215

• Stereo Two-Third Octave Graphic Equalizer
• 15 2/3-octave filters on each channel for sound system equalization
• Switchable infrasonic filter and ground-lift
• Selectable (6 or 12 dB) range of boost/cut
• Active-balanced 3-pin XLR-type and TRS 1/4-inch inputs
• Space saving on rack space chassis with internal power supply with IEC connector