GENERAL INFORMATION
HQ-231 DUAL CHANNEL 31 BAND 1/3 OCTAVE GRAPHIC EQUALIZER WITH FDC™
Congratulations on the purchase of your new ART equalizer. This professional equalizer is perfect for
all applications and is also well suited for signal processing in situations where feedback is possible.
It’s features include ART FDC™ (Feedback Detection Circuit), and constant Q circuitry with a 3%
center frequency accuracy. It also features LED level metering, selectable range 6dB or 12dB, active
balanced and unbalanced input/output connectors, RFI filters, independent variable Hi Pass (low cut)
and Low Pass (high cut) filters, variable input level control, passive bypass switch, clip level indicator,
ground lift switch, and selectable line voltage switch. The unit also features automatic bypass if power
to the unit is lost.
FDC™ - ART’s FEEDBACK DETECTION CIRCUIT
FDC (Feedback Detection Circuitry – designed and developed by ART Engineering) instantly illumi-
nates the corresponding EQ band with the greatest signal. That is, if feedback occurs, FDC identifies
the band with the feedback frequency for quick correction.
During operation, various LED’s will illuminate as the signal passes. The loudest band will correspond
with the brightest LED. When you hear feedback, FDC (and it’s brightest LED) shows you where to
attenuate.
FDC confirms what you hear (feedback), and shows you exactly where it is. You’ll also know you
have properly attenuated the signal as the LED reduces its illumination. FDC - it is both precise and
simple.
FDC APPLICATIONS
FDC allows you to observe those frequency bands with the greatest energy when program material is
being played. In a live sound system where the HQ EQ is in the path between a microphone and
loudspeakers, dominant room modes may be seen as bands with a lot of energy when the sound
system gain is increased. These bands with excess energy will brightly illuminate the corresponding
led in the offending frequency’s fader. These frequencies will generally be the first where feedback is
likely to occur.
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