Operating instructions

GENERAL INFORMATION

Congratulations on the purchase of your new ART equalizer. This professional equalizer is perfect for

virtually any audio application where frequency tailoring is needed. It’s features include: constant Q

circuitry with accurate center frequencies, selectable 6dB or 12dB range, active balanced and unbal-

anced 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. The unit also features automatic relay bypass of audio if power to the unit

is lost or too low. Rugged construction and solid audio performance make these equalizers particu-

larly well suited to fixed installation as well as touring live sound systems.

INSTALLATION

This series of equalizers are designed for mounting in a standard 19” equipment rack or one of the

many rack type portable cases available on the market. The vertical height is 1.75 inches for the

HD131 and HD215, and 3.5 inches for the HD231. The depth is 7 inches.

POWER CONNECTORS

These equalizers have internal power supplies and are designed for operation with 120 or 240 volt

(as determined by the rear fuse block orientation), 50-60Hz mains supply. In new installations and

portable sound systems, or any situation where the mains power is in question, it is wise to confirm

the voltage and select the appropriate line voltage setting BEFORE connecting the equalizer to power

sources.

INPUT/OUTPUT CONNECTIONS

The HD series graphic equalizers have 3 sets of input and output connectors wired in parallel: XLR,

1/4" phone, and Euroblock barrier strip connectors. Only one of the 3 inputs should be used per

channel. Any combination of output connectors may be used.

XLR connections are balanced where pin 2 is High (+), pin 3 is Low (-), and pin 1 is ground.

1/4" Phone connections may be used balanced or unbalanced. When balanced, the tip is High (+),

the ring is Low (-) and the sleeve is ground. To use unbalanced use a mono ¼” phone cable, this will

automatically ground the ring to the sleeve.