Applied Research and Technology (ART) 451, 455, 441 Owner's Manual

441 DUAL CHANNEL 15 BAND 2/3 OCTAVE GRAPHIC EQUALIZER

451 SINGLE CHANNEL 31 BAND 1/3 OCTAVE GRAPHIC EQUALIZER

455 DUAL CHANNEL 31 BAND 1/3 OCTAVE GRAPHIC EQUALIZER

The new ART 400 Series of Precision Graphic Equalizers have been designed
and engineered to exceed extremely high standards for audio performance and
functionality. These innovative, high-quality equalizers are perfect for virtually any
audio application where precision frequency tailoring, reliable performance, rug­ged design and extremely silent processing is of the utmost priority.

Active Filter Sections

The 400 Series of Precision Graphic Equalizers
feature active filter sections, which incorporate a
constant-Q design. This constant-Q design, with
accurate precision center frequencies, ensures
that the bandwidth of every individual filter will be
narrow enough to prevent unnecessary interaction
between filters, yet still create an equalization curve
wide enough to produce the exact and precise
processing of audio frequencies the user seeks.

Precision Slide Potentiometers

The 400 Series of Precision Graphic Equalizers
utilize two x thirty-one 20mm oil-damped precision
slide potentiometers. These center-detented,
precision faders are graphically positioned at 1/3­octave ISO frequencies between 25Hz-20kHz.

Independent Variable Hi and Low Pass Filtering

In order to deliver superlative performance and
control, the 400 Series of Precision Graphic Equal­izers incorporates independent variable Hi Pass
(low cut) and Low Pass (high cut) filters. Having
separate and variable precision control for both
the Hi Pass and Low Pass filters allow the user to
custom tailor the audio signal to perfection.

Many competing products only feature shelving
switches which have a fixed frequency point.
Others do not have separate filtering for both high
and low frequencies. These designs do not offer
the precision or control of an ART 400 Series
equalizer.

Automatic Relay Bypass

The 400 Series of Precision Graphic Equalizers
also feature automatic relay bypass of audio, an
essential function if power to the unit is lost.
Rugged construction and solid audio performance
make these equalizers particularly well suited to
fixed installation as well as touring live sound
systems.

Additional Controls and Indicators

The 400 Series of Precision Graphic Equalizers
utilize a variable input level control, clip level
indicator, ground lift switch, and selectable line
voltage.

Additional features include selectable Scale Switch­ing - (High Slider Resolution +/-6dB - or Normal
Resolution (+/-12dB), active balanced and unbal­anced input/output connectors, and RFI filtering.

A passive Bypass switch allows for direct compari­son between the equalized and non-equalized
signal for each channel.

Multiple Connectivity

The 400 Series of Precision Graphic Equalizers are
connectable with a wide variety of audio devices
and each unit has three sets of input and output
connectors wired in parallel. These connections
include XLR, 1/4" phone, and RCA phono connec­tors.

Durability by Design

The 400 Series of Precision Graphic Equalizers are
designed and engineered to be durable and rug­ged. They are an ideal choice when the need for a
robust equalizer is of paramount concern, are
designed for mounting in a standard 19" equipment
rack or one of the many rack type portable cases in
existence. The vertical height is 1.75 inches for the
441 and 451, and 3.5 inches for the 455. The depth
is 7 inches.

Precision and Quality

When considering quality equalization, the ART
400 Series of Precision Graphic Equalizers are an
excellent choice. They deliver extremely precise,
powerfully flexible and simply great sounding
equalization, with the quality features and reliable
design criteria necessary for top-level audio per­formance.

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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. Rugged construction and solid audio performance make these equalizers particularly 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 441

and 451, and 3.5 inches for the 455. The depth is 7 inches.

POWER CONNECTORS

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

50-60Hz mains supply. Power consumption is 7.5 watts. 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 400 series graphic equalizers have 3 sets of input and output connectors wired in parallel: XLR,

1/4" phone, and RCA phono 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 phone cable, this will

automatically ground the ring to the sleeve.

RCA connections are always unbalanced.

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SIGNAL LEVELS

Signal levels from -10 dBu to +4 dBu are considered normal with maximum levels of approximately

+19dBu. Do not connect microphones directly to the equalizer. Microphones require a preamp.

CHASSIS GROUNDING

The equalizers are equipped with a rear panel Ground lift switch. After setting up your system, if the

system exhibits excessive hum or buzzing, the problem may be a ground incompatibility between

your equalizer and other equipment in the same system. There are several combinations that can be

tried. NOTE: ALWAYS TURN YOUR AMPLIFIERS DOWN BEFORE CHANGING GROUNDS. Try

different combinations of lifting grounds on units that are supplied with ground lift switches or make

sure all chassis are connected to earth ground, either through the AC Power cord ground or by the

front panel rack mount screws.

If the 400 series equalizer is mounted in a grounded rack of equipment, the ground to the case of the

equalizer may be lifted to prevent multiple ground paths, which may cause a ground loop to occur.

OPERATING INSTRUCTIONS

Before starting to equalize your sound system there is some information you should know and proce-

dures you should follow. Your equalizer is equipped with a bypass switch. The bypass switch, when

activated, lights the LED and cancels all equalization settings while allowing signal to flow through the

unit at unity gain.

Also included is a range selection switch with LED indicators, 6dB =green, 12dB= yellow. In addition

to the range selection switch there is an output level control potentiometer. The level control operates

between off and +6dB. Note: If there is too much gain, your equalizer has a red LED Clip indicator

that illuminates when signals are within 4dB of clipping. If the Clip LED flashes occasionally, this is

okay, but if this LED is steadily on you must readjust the level control.

INITIAL SET UP

Here are some tips to help you with the initial set up:

1. Set channel levels to the center detent 0dB on the front panel.

2. Select the Bypass switch to bypass the equalizer (Note: The red LED is on).

3. Set the frequency slide controls to the center detent (or 0dB).

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