ART EQ300 Series Graphic Equalizers User Guide
- June 17, 2024
- ART
Table of Contents
USER’S GUIDE
EQ300 Series Graphic Equalizers
EQ341 DUAL
CHANNEL 15-BAND 2/3 OCTAVE EQUALIZER
EQ351 SINGLE CHANNEL 31-BAND 1/3 OCTAVE EQUALIZER
EQ355 DUAL CHANNEL 31-BAND 1/3 OCTAVE EQUALIZER
IMPORTANT SAFETY INSTRUCTIONS – READ FIRST
This symbol, wherever it appears, alerts you to the presence of uninsulated
dangerous voltages inside the enclosure that may be sufficient to constitute a
risk of shock.
This symbol, wherever it appears, alerts you to important operating and
maintenance instructions in the accompanying literature.
Please read the manual.
Read instructions
Retain these safety and operating instructions for future reference. Heed all
warnings printed here and on the equipment. Follow the operating instructions
printed in this user guide.
Do not open
There are no user serviceable parts inside. Refer any service work to
qualified technical personnel only.
Power sources
Only connect the unit to mains power of the type described in this user guide
or marked on the rear panel. The power source must provide a good ground
connection.
Power cord
Use the power cord with sealed mains plug appropriate for your local main
supply as provided with the equipment. If the provided plug does not fit into
you outlet consult your service agent. Route the power cord so that it is not
likely to be walked on, stretched or pinched by items placed upon or against.
Grounding
Do not defeat the grounding and polarization means of the power cord plug. Do
not remove or tamper with the ground connection on the power cord.
Moisture
To reduce the risk of fire or electrical shock, do not expose the unit to
rain, moisture or use in damp or wet conditions. Do not place container of
liquid on it, which may spill into any openings
Heat
Do not locate the unit in a place close to excessive heat or direct sunlight,
as this could be a fire hazard.
Locate the unit away from any equipment, which produces heat such as: power
supplies, power amplifiers and heaters.
Environment
Protect from excessive dirt, dust, heat, and vibration when operating and
storing. Avoid tobacco ash, drink spillage and smoke especially that
associated with smoke machines.
Handling
Protect the controls from damage during transit. Use adequate padding if you
need to ship the unit. To avoid injury to yourself or damage to the equipment
take care when lifting, moving or carrying the unit.
Servicing
Switch off the equipment and unplug the power cord immediately if it is
exposed to moisture, spilled liquid or the power cord or plug becomes damaged
during a lightning storm or if smoke odor or noise is noted. Refer servicing
to qualified technical personnel only.
Installation
Install the unit in accordance with the instruction printed in the user guide.
OVERVIEW
The ART EQ300 Series of graphic equalizers have been designed and engineered
to 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 important.
Active Filter Sections
The EQ300 Series of graphic equalizers feature active filter sections, which
incorporate a constantQ 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 EQ300 Series of graphic equalizers utilize 20mm precision slide
potentiometers. These center-detented, precision faders are graphically
positioned on ISO center frequencies between 25Hz-16kHz for the EQ341, 20Hz to
20kHz for the EQ351 and EQ355.
Independent Variable Hi and Low Pass Filtering
In order to deliver superlative performance and control, the EQ351 and EQ355
graphic equalizers incorporate 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, allows 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 the ART EQ300 Series.
Additional Controls and Indicators
The EQ300 Series of graphic equalizers utilize a variable output level
control, clip level indicator, ground lift switch, and selectable line
voltage.
Additional features include selectable scale switching – high slider
resolution (±12dB) or normal resolution (±6dB), active balanced and unbalanced
input/output connectors, and RFI filtering.
A passive bypass switch allows for direct comparison between the equalized and
nonequalized signal for each channel.
Multiple Connectivity
The EQ300 Series of graphic equalizers can be connected with a wide variety of
audio devices. Each unit has three sets of input and output connectors wired
in parallel. These connections include XLR connectors, 1/4″ phone jacks and
RCA phono jacks.
Durability by Design
The EQ300 Series of 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. They 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 EQ341 and EQ351, and 3.5
inches for the EQ355. The depth is 7 inches, exclusive of power cord.
Rugged construction and solid audio performance make these equalizers
particularly well suited to fixed installation as well as touring live sound
systems.
Precision and Quality
When considering quality equalization, the ART EQ300 Series of graphic
equalizers are an excellent choice. They deliver extremely precise, powerfully
flexible and simply great sounding equalization, with the quality features and
reliable design necessary for top-level audio performance.
GENERAL INFORMATION
Your ART equalizer is a professional quality unit 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 unbalanced input and output connectors, RFI
filters, independent variable Hi Pass (low cut) and Low Pass (high cut)
filters (for the EQ351 and EQ355), variable input level control, passive
bypass switch, clip level indicator, ground lift switch, and selectable line
voltage. 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 EQ351 and EQ341, and 3.5
inches for the EQ355. The depth is 7 inches, exclusive of the power cord.
POWER CONNECTORS
These equalizers have internal power supplies and are designed for operation
with 120 or 240 volt (as determined by the rear panel line voltage switch),
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 EQ300 series graphic equalizers have three sets of input and output
connectors wired in parallel: 1/4″ phone, XLR, and RCA connectors. Only one of
the three inputs should be used per channel. Any combination of output
connectors may be used.
1/4″ phone jack 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 1/4” phone cable, which will automatically ground the
ring to the sleeve.
XLR connections are balanced where pin 2 is High (+), pin 3 is Low (-), and
pin 1 is Ground.
RCA jack connections are unbalanced.
SIGNAL LEVELS
Signal levels from -10dBm to +4dBm are considered normal with maximum levels
of approximately +18dBm balanced or +22dBm unbalanced. Do not connect
microphones directly to the equalizer.
Most microphones, as well as instrument pickups, require a preamp to get the
signal level up to a line level. The outputs of the equalizer are also
designed to connect into line level inputs and should not be connected into
sensitive microphone or instrument Inputs for best results.
CHASSIS GROUNDING
The equalizers are equipped with a rear panel grounding screw and Ground Lift
switch. The Ground Lift switch should normally be set to the GND position.
After set up, if your system exhibits excessive hum or buzzing, the problem
may be a due to a ground differential between your equalizer and other
equipment in the same system. The Ground Lift switch lets you try several
combinations to minimize system hum.
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 grounds or by the rear panel grounding
screws.
If the EQ300 series equalizer is mounted in a grounded rack of equipment, the
ground to the grounding screw of the equalizer may be lifted to prevent
multiple ground paths, which may cause a ground loop to occur.
INITIAL SETUP
Before starting to equalize your sound system there is some information you
should know and procedures you should follow. Your equalizer is equipped with
a bypass switch. The BYPASS switch, when activated, lights the bypass LED and
cancels all equalization settings while allowing signal to flow directly
through the unit at unity gain.
Also included is a RANGE selection switch with LED indicators, ±6dB (green),
±12dB (yellow). This switch changes how much effect the slide controls have.
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 6dB of clipping. If the
CLIP LED flashes occasionally, this is okay, but if this LED is on steadily
you should reduce the level control.
Here are some tips to help you with the initial set up:
- Set channel output LEVELs to the center detent (0dB) on the front panel.
- Select the BYPASS switch to bypass the equalizer. (Note: The red LED is on)
- Set the frequency slide controls to the center detent (0dB).
- If applicable, set the HI PASS filter to 10Hz and the LOW PASS filter to 40kHz.
- Select the ±6dB RANGE. (Note: The green LED is on)
- Apply a signal to the system and if the CLIP LED is on, reduce your signal to the unit.
- Unselect the BYPASS switch (Note: The red LED is off)
- If the CLIP LED is on, turn down the Output LEVEL control.
- You may now start equalizing your system.
- If you do not have enough equalization control, switch the range switch to the ±12dB setting.
OPERATION
FRONT PANEL CONTROLS 
POWER SWITCH
To turn the equalizer on or off, press the upper or lower portion of the POWER
switch. CAUTION: Always turn on your equalizer BEFORE your power amplifiers
are turned on, and always turn off your equalizer AFTER your power amplifiers
have been turned off.
FILTER LEVEL CONTROLS
Each of these sliders controls the signal level of each of the 31 (or 15)
bandpass filters. A detent at the center position helps center the controls
for a flat response.
FILTER RANGE SWITCH & INDICATORS
The gain range of the filter sliders is switchable (as a group) from ±6dB to
±12dB for maximum boost/cut capability. At ±6dB the green LED will illuminate,
and at ±12dB the yellow LED will illuminate.
BYPASS SWITCH & CLIP INDICATOR LED
When the red BYPASS LED is illuminated, this indicates that the unit or
channel is in the bypass mode. Signal is routed directly from the input to the
output without passing through any circuitry (often referred to as ”hard-wire
bypass”). Use this switch to compare equalized and unequalized material, or to
bypass the EQ section in the event of total unit failure.
The red CLIP LED illuminates if any section of the equalizer is near clipping.
Occasional flickering of this LED is acceptable, but if it remains on more
than intermittently, you should reduce the output level of the preceding
equipment or, if that is not possible, turn down the equalizer’s LEVEL control
to avoid audible distortion.
HI PASS FILTER (LOW-CUT FREQUENCY CONTROL) (EQ351 and EQ355 only)
To cut down on unwanted low frequency signals, this control determines the
roll-off frequency of the Hi-Pass Filter (HPF). The roll-off frequency can be
adjusted from 10Hz to 250Hz by turning this knob.
Because of its high roll-off slope, the HPF can be efficiently used to cut
down hum and low frequency noise from preceding instruments, or to reduce low
frequency resonances, when speakers are installed in an enclosed acoustic
environment. It is also very effective at removing power robbing and
potentially destructive rumble.
LOW PASS FILTER (HIGH-CUT FREQUENCY CONTROL) (EQ351 and EQ355 only)
To cut down on unwanted high frequency signals, this control determines the
roll-off frequency of the Low-Pass Filter (LPF). The roll-off frequency can be
adjusted from 3kHz to 40kHz by turning the knob. Because of its high roll-off
slope, the LPF can be effectively used to cut down the high frequency noise
from preceding instruments, or roll-off excessive high frequency sounds to
obtain a more natural sound in some acoustic situations.
LEVEL CONTROL
This controls the output signal level from the equalizer. Turn this control
down if the CLIP LED illuminates steadily (meaning too strong an input
signal). Unity gain can be set by adjusting this knob so that as you toggle
the BYPASS switch the overall level sounds the same.
Signal levels should be kept normalized through the equalizer. That is, the
signal level, when bypassed, should be the same (or a little lower) than when
active.
REAR PANEL CONNECTORS & CONTROLS
POWER CORD
This cord is used to connect the AC power source to your equalizer.
CAUTION: Equipment for USA installation includes a power cord with a
three-pin polarized plug. DO NOT REMOVE THE CENTER GROUNDING PIN.
FUSE HOLDER, LINE VOLTAGE SWITCH & GROUNDING SCREW
This fuse holder contains the AC primary fuse. This fuse should be replaced
with the same type fuse if it is blown. If they continuously blow, stop
replacing fuses and refer servicing to qualified personnel. CAUTION: After
checking the AC supply voltage, be sure that the correct fuse is in the fuse
holder – 0.5Amp (500mA) for 95-125VAC, as well as for 220-240VAC. When
changing the fuse, make sure that the holder is seated securely. The position
of the line voltage switch determines the line voltage range and is labeled on
the switch
GROUND LIFT SWITCH
This switch is used to disconnect signal
ground from the mains and chassis earth ground. You may set the switch to the
LIFT position if ”Hum”, caused by a ground loop, can be heard at the speakers.
INPUT/OUTPUT CONNECTORS
1/4″ TRS Phone Jacks
The TRS (Tip Ring Sleeve) connectors are balanced and wired as Tip = High (+),
Ring = Low (-), and Sleeve = Ground.
For balanced connections using 1/4″ TRS phone plugs, wire them as follows:
tip = High (+)
ring = Low (-)
sleeve = Ground
For unbalanced connections using 1/4″ TRS or mono (tip/sleeve) phone plugs,
wire them as follows:
tip = High (+)
ring = no connection
sleeve = Ground
XLR Connectors
The XLR input connectors are balanced and wired as Pin 2 = High (+), Pin 3 =
Low (-), and Pin 1 = Ground.
RCA Jacks
The RCA jacks are unbalanced, with the pin High (+) and the outside Low (-).
APPLICATIONS
Graphic equalizers may be used wherever modification of the frequency contour
of a sound system is needed. A graphic equalizer is a solution to any number
of sound problems or creative urges. 
WARRANTY INFORMATION
Limited Warranty
Applied Research and Technology will provide warranty and service for this
unit in accordance with the following warrants:
Applied Research and Technology, (ART) warrants to the original purchaser that
this product and the components thereof will be free from defects in
workmanship and materials for a period of three years from the date of
purchase. Applied Research and Technology will, without charge, repair or
replace, at its option, defective product or component parts upon prepaid
delivery to the factory service department or authorized service center,
accompanied by proof of purchase date in the form of a valid sales receipt.
Exclusions
This warranty does not apply in the event of misuse or abuse of the product or
as a result of unauthorized alterations or repairs. This warranty is void if
the serial number is altered, defaced, or removed.
ART reserves the right to make changes in design or make additions to or
improvements upon this product without any obligation to install the same on
products previously manufactured. ART shall not be liable for any
consequential damages, including without limitation damages resulting from
loss of use. Some states do not allow limitations of incidental or
consequential damages, so the above limitation or exclusion may not apply to
you. This warranty gives you specific rights and you may have other rights,
which vary from state to state.
For units purchased outside the United States, an authorized distributor of
Applied Research and Technology will provide service.
SERVICE
The following information is provided in the unlikely event that your unit requires service.
- Be sure that the unit is the cause of the problem. Check to make sure that the unit has power supplied, that all cables are connected correctly, and that the cables themselves are in working condition. You may want to consult with your dealer for assistance in troubleshooting or testing your particular configuration.
- If you believe that the ART unit is at fault, go to www.artproaudio.com. You may contact Customer Service for more assistance, or directly request a Return Authorization for service in the “resources” area of the website.
- If you are returning the unit for service, pack the unit in its original carton or a reasonable substitute. The original packaging may not be suitable as a shipping carton, so consider putting the packaged unit in another box for shipping. Print the RA number clearly on the outside of the shipping box. Print your return shipping address on the outside of the box.
- Include with your unit: a note with the RA number and your contact information, including a return shipping address (we cannot ship to a P.O. box) and a daytime phone number, and a description of the problem, preferably attached to the top of the unit. Also include a copy of your purchase receipt.
Fill in the following information for your reference:
Date of purchase ………………………………………..
Purchased from …………………………………………
Serial number ……………………………………………
SPECIFICATIONS
EQUALIZER
Band| 2 x 15, 2/3 octave, ISO spacing (EQ341)
1 x 31, 1/3 octave, ISO spacing (EQ351)
2 x 31, 1/3 octave, ISO spacing (EQ355)
Type / Accuracy| Constant-Q / 3% center frequency
Travel| 20mm w/ positive center detent
Range| ±6dB or ±12dB, selectable
Overall Gain Range| Off to +6dB (unbalanced out) sliders centered
Off to +12dB (balanced out) sliders centered
INPUTS
Type| Active balanced/unbalanced
Connectors| 3-Pin XLR, 1/4” TRS (balanced), RCA (unbalanced)
Impedance| 20k Ohms balanced; 15k Ohms unbalanced
Maximum Level|
OUTPUTS
Type| Active balanced/unbalanced
Connectors| 3-Pin XLR, 1/4” TRS (balanced), RCA (unbalanced)
Impedance| <150 Ohms, typical
Maximum Level|
Passive Bypass Switches| Yes
Overload LED Threshold| 6 dB below clipping, (all filters set to flat)
High Pass Filter (EQ351,EQ355)| 10-250Hz, 12dB/octave
Low Pass Filter (EQ351, EQ355)| 3k-40kHz, 12dB/octave
Frequency Response| 20-20kHz, ±0.5dB
THD + Noise| 0.01%
Signal to Noise Ratio| -94dB
Channel Separation| >50dB
POWER (switchable)| 95-130VAC, 50/60Hz
190-250VAC, 50Hz
POWER CONSUMPTION| 12 Watts
SIZE| 1.75” H 19” W 7” D (1U) (EQ351 and EQ341) (4.45cm 48.3cm 17.8cm)
3.5” H 19” W 7” D (2U) (EQ355) (8.9cm 48.3cm 17.8cm)
WEIGHT| 7.1 Ibs (3.2 kg) (EQ351 and EQ341) 11.6 Ibs (5.2 kg) (EQ355)
www.artproaudio.com
E-mail: [email protected]
© 2010 Applied Research & Technology
EQ341, EQ351, EQ355
V1.0
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