OPERATION MANUAL
ART XL 231 Dual 31 Band, 1/3 Octave Extended, Long Throw, Professional Equalizer
IMPORTANT SAFETY INSTRUCTION – READ FIRST
This symbol, whenever it appears, alerts you to the presence of uninsulated
dangerous voltage 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
voltage instructions in the accompanying literature. Please Read 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 Operation Manual.
Do not open:
There are no user serviceable parts inside. Refer any service work to qualified technical personnel only.
Power sources:
Connect the unit to mains power only of the type described in this Operation Manual 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 moisture or use in damp or wet
conditions. Do not place container of liquid on it.
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, 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 instructions printed in the Operation Manual.
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ART XL 231 Dual 31 Band, 1/3 Octave Extended, Long Throw, Professional Equalizer
INTRODUCTION
The new ART XL 231 Dual 31 Band, 1/3 Octave Extended Long Throw Professional
Equalizer has been designed and engineered to exceed extremely high standards for
audio performance and functionality. This innovative, high-quality equalizer is perfect for
virtually any audio application where precision frequency tailoring, reliable performance,
rugged design and extremely silent processing are of the utmost priority.
Active Filter Sections
The XL 231 features active filter sections, which incorporate a constant-Q design.This
constant-Q design, with its accurate precision center frequencies, ensures that the
bandwidth of every individual filter will be narrow enough to prevent unnecessary
interaction between ajacent filters, yet still create an equalization curve wide enough to
produce the exact and precise processing of audio frequencies the user seeks.
Filter circuitry incorporates high quality low noise components including 1% resistors,
and, precision high performance 2% film capacitors.
Enhanced Cut Mode
The XL 231 offers an enhanced cut mode which allows more narrow filters and deeper
cut of -18dB. This helps when trying to tame resonance and minimizing overall spectral
changes. Only each filter’s cut mode is enhanced while their boost characteristic
remains unchanged.
Precision Slide Potentiometers
The XL 231 uses 45mm precision slide potentiometers. These center-detented, metal
shaft precision faders are graphically positioned on ISO center frequencies between
20Hz to 20kHz. The sliders feature a grounded center tap to assure that the filter is out
of the circuit when the control is at its center detent.
Hi and Low Trim controls
These unique controls allow a gentle slope to be added, or subtracted from the overall
frequency response. Both controls hinge at the middle of the spectrum and allow subtle
changes to the overall sound without the need to adjust many sliders. Although similar
in concept to tone controls, these differ in their well controlled precision straight curves,
and, have less selectivity so the Trim controls don’t have a “sound” as a typical tone
control will.
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ART XL 231 Dual 31 Band, 1/3 Octave Extended, Long Throw, Professional Equalizer
Variable Low Cut Filtering
To help keep bass under control, the XL 231 Graphic Equalizer incorporates a variable
swept Low Cut filter.
Automatic Relay Bypass
The XL 231 Graphic Equalizer also features automatic relay bypass of audio, an
essential function if power to the unit is lost. Rugged construction and solid audio
performance make this equalizer particularly well suited to fixed installation as well as
touring live sound systems.
Additional Controls and Indicators
The XL 231 Graphic Equalizer includes a variable output level control, 10 segment level
bar with peak hold, clip level indicator, 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 front panel Bypass switch allows direct comparison between the equalized and nonequalized signal for each channel.
Multiple Connectivity
The XL-231 Graphic Equalizer may be connected to a wide variety of audio devices.
It has three sets of input and output connectors: XLR, ¼” phone, and detachable
Euroblock barrier strip connectors. The inputs are wired in parallel. The XLR and Euro
block output connections are also wired in parallel. A separate output circuit is used for
the ¼” phone output. It provides a balanced connection that results in the same output
level when operated with balanced, or unbalanced connections.
Durability by Design
The XL-231 Graphic Equalizer is designed and engineered to be durable and rugged.
It is an ideal choice when the need for a robust equalizer is of paramount concern. It is
designed for mounting in a standard 19" equipment rack or portable case.
Precision and Quality
When considering quality equalization, the XL-231 Graphic Equalizer is an excellent
choice. It delivers 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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ART XL 231 Dual 31 Band, 1/3 Octave Extended, Long Throw, Professional Equalizer
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.
INSTALLATION
This equalizer is designed for mounting in a standard 19” equipment rack or rack type
portable case. It is 3 standard rack units in height or 5.25 inches. The depth is 7 inches
behind the front panel.
POWER CONNECTORS
This equalizer has internal power supplies 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 XL 231 has three sets of input and output connectors. These connections include
XLR, ¼” balanced or unbalanced phone, and detachable Euroblock barrier strip
connectors. The inputs are wired in parallel. The XLR and Euroblock output connections
are also wired in parallel. A separate output circuit is used for the ¼” phone outputs
which provides the same output level when used with either balanced, or unbalanced
connections.
For optimum performance use balanced connections. Balanced connections help
eliminate external sources of electrical noise.
EUROBLOCK CONNECTIONS
Insert the wires, and then snug down with the set screw. The entire barrier strip can be
detached for quick service without disconnecting the individual wires.
SIGNAL LEVELS
Signal levels from -10dBu to +4dBu are considered normal with maximum levels of
approximately +24dBu. 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.
Please refer to the APPLICATION NOTES for more information on operation levels.
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ART XL 231 Dual 31 Band, 1/3 Octave Extended, Long Throw, Professional Equalizer
OPERATING INSTRUCTIONS
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 red LED and cancels all
equalization settings while allowing signal to flow directly through the unit at unity gain.
When in the active state, the green LED is on.
Also included is a range selection switch. Normal range is ± 12dB (+12/-18 when
Enhanced Cut Mode is active). When Fader Range is set to ÷2, the yellow LED is
illuminated and the range is cut in half to ±6dB (+6/-9 when Enhanced Cut Mode is
active). 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 input signal, or, the equalizer has many filter bands boosted,
the red LED Clip indicator will indicate when signals are within 6dB of clipping. If the
Clip LED flashes occasionally, this is okay, but if this LED is steadily on you should
reduce the input signal level or the amount of boost in the filter bands. Reducing the
output level will not reduce clipping if it occurs.
INITIAL SET UP
Here are some tips to help you with the initial set up:
1. Set channel output levels to the center 0dB on the front panel.
2. Select the Bypass switch to bypass the equalizer (Note: The red LED is on).
3. Set the frequency band slide controls to the center detent (0dB).
4. Set the Low Cut filter to 10Hz.
5. Select the ÷2 range (Note: The yellow LED is on).
6. Apply signal to the system and if the Clip LED is on, reduce your signal to the unit.
7. Release the bypass switch (Note: The red LED is off, the green LED is on.).
8. You may now start equalizing your system.
9. If you do not have enough equalization control, release the Fader Range switch to
the out position, yellow LED off.
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ART XL 231 Dual 31 Band, 1/3 Octave Extended, Long Throw, Professional Equalizer
FRONT PANEL CONTROLS
POWER SWITCH
To turn the equalizer ON or OFF, press (and release) the POWER ON/OFF button.
CAUTION: Always turn on your mixer and 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 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) for maximum boost/cut
flexability. Normal range is ± 12dB (+12/-18 when Enhanced Cut Mode is active). When
Fader Range is set to ÷2, the yellow LED is illuminated and the range is cut in half to
±6dB (+6/-9 when Enhanced Cut Mode is active).
ENHANCED CUT MODE
The XL 231 offers an Enhanced Cut mode which has a more narrow filter bandwidth
and additional cut range of -18dB. This helps when trying to tame resonance and
minimizing overall spectral changes. When Enhanced Cut is used with the ÷2 range, the
maximum cut is -9dB instead of -18dB. As can be seen in the graphs below, only filter
cut shapes are affected, boost curves are the same regardless of cut mode.
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ART XL 231 Dual 31 Band, 1/3 Octave Extended, Long Throw, Professional Equalizer
BYPASS SWITCH
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
unlikely event of total unit failure.
LEVEL BARS AND CLIP INDICATOR LED
Clip Indicator
This red 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,
reduce the amount of boost in the equalizer filter bands. Reducing output level will not
prevent clipping of the equalizer circuitry.
Level Bars
The 10 segment Level Bars provide an easy to read indication of signal levels at the
output of the equalizer. The Level Bars also provide a peak hold function. This allows
viewing both the peak level as well as the average signal level in a glance. Peak level is
especially important when driving power amplifiers or A-D converters which tend to clip
hard. The peak level indicator helps to set level in a manner that will avoid this harsh
clipping.
LOW-CUT FILTER FREQUENCY CONTROL
To cut down on unwanted low frequency signals, this control determines the roll-off
frequency of the Low Cut Filter. The roll-off frequency can be adjusted from below 10Hz
to 250Hz by turning this knob. Because of its high roll-off slope, the filter can be
efficiently used to cut down hum and low frequency noise from preceding devices, or to
reduce low frequency resonance when speakers are installed in an enclosed acoustic
environment. It is also very effective at removing power robbing and potentially
destructive rumble.
HI AND LO TRIM CONTROLS
These unique controls allow a gentle slope to be added, or, subtracted from the overall
frequency response. Both controls hinge at the middle of the spectrum and provide
subtle changes to the overall sound without the need to adjust many sliders. Although
similar in concept to tone controls, these differ in their well controlled precision straight
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ART XL 231 Dual 31 Band, 1/3 Octave Extended, Long Throw, Professional Equalizer
curves, and, have less selectivity so the Trim controls don’t have a “sound” as a typical
tone control will.
The Trim controls are typically used after the overall equalization has been set, yet the
balance between highs, mids, and lows needs to be adjusted. For example, when
providing sound at a venue, the equalizer may be set during a sound check. When the
audience later fills the room, the sound may get duller due to the added high frequency
absorption. The HI trim may be increased to eliminate the dullness without the need to
re-equalize the entire system. Note also that in either indoor or outdoor events, changes
in temperature or humidity can affect high frequency absorption and the Trim controls
are useful to help compensate for these changes.
LEVEL CONTROL
This controls the output signal level from the equalizer. 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. One reason for
this is if the equalizer loses power (which causes the unit to go into bypass), the signal
will be equal or lower than the active equalizer gain. This will ensure that a signal with
undesirably higher levels will not be passed inadvertently.
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ART XL 231 Dual 31 Band, 1/3 Octave Extended, Long Throw, Professional Equalizer
REAR PANEL CONNECTORS
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
This fuse holder contains the AC primary fuse. This fuse should be replaced with the
same type fuse if it is blown. If fuses continuously blow, stop replacing them 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 for 95-125VAC, as well for 220240VAC. The orientation of the fuse holder determines the line voltage range and is
labeled on the rear of the holder. When changing the fuse, make sure that you insert the
holder in the correct orientation for your local line voltage.
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ART XL 231 Dual 31 Band, 1/3 Octave Extended, Long Throw, Professional Equalizer
INPUT/OUTPUT CONNECTORS
Although the XL 231 may be used with unbalanced connections, for optimum
performance use balanced connections. Balanced connections help eliminate external
sources of electrical noise.
Only one of the 3 inputs should be used per channel. Any combination of output
connectors may be used.
¼” TRS Phone
The TRS (Tip Ring Sleeve) ¼” 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.
The TRS ¼” Phone connector is balanced and wired as:
Tip = High (+)
Ring = Low (-)
Sleeve = Ground.
XLR
The XLR input connector is balanced and wired as:
Pin 2=High (+)
Pin 3=Low (-)
Pin 1=Ground.
EURO BLOCK
The detachable Euroblock connections are wired as shown on the rear panel.
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ART XL 231 Dual 31 Band, 1/3 Octave Extended, Long Throw, Professional Equalizer
APPLICATION NOTES
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.
The Audio Spectrum, a Reference
In general, what we hear extends over a range of frequencies from 20 Hertz (Hz) to 20
Kilohertz (KHz). This equates to roughly ten and one third octaves, an octave being a
factor of two. The most perceived range lies between 300Hz to 3KHz, the region where
most voice information occurs. The audio spectrum may be divided into seven
frequency ranges. We will define these ranges in the following text.
Low Bass: 20Hz to 40Hz
This is the lowest of normally audible octaves. Below these frequencies, sounds are
more felt than heard. These subaudible frequencies are produced by earthquakes,
building vibrations, elephants and huge organ pipes. Low bass information include the
fundamental frequencies of the lowest keys on organs, synthesizers and pianos.
Mechanical rumble also falls within the range below 40Hz. These low bands on the
equalizer may be useful for tailoring the low frequency response of some speakers and
microphones.
Bass: 40Hz to 160Hz
These two octaves are normally perceived as the bass frequencies. Instruments such
as the electric and string bass, tuba, bass drum and the lower notes of keyboard
instruments fall within this range. The bottom end of most music is reflected here.
Mid Bass: 160Hz to 315Hz
In this octave, the transition between bass and midrange occurs. Low frequency
crossover points in speaker systems are usually selected in this range. Modification of
voice and drum fundamentals as well as the character of the upper bass and lower
brass instruments can be achieved by manipulating the levels of these frequencies.
Mids: 315Hz to 2.5KHz
The fundamental frequencies of voice and musical instruments occurs within these
three octaves. The upper harmonics of bass instruments also falls within this range.
The intelligibility of speech falls within this range of frequencies. Just as a point of
reference, these three octaves are about the same bandwidth as a telephone.
Upper Mids 2.5KHz to 5KHz
In this octave, what we perceive as presence, definition and attack are subject to
control. Boosting these bands adds crispness while cutting them eliminates vocal
sibilants such as hiss. Your ear is most sensitive in this frequency range.
Highs: 5KHz to 10KHz
Brilliance, vocal fricatives and intensity of the sound are adjusted in this frequency
range. The snap of percussive instruments especially cymbals and the harmonic
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ART XL 231 Dual 31 Band, 1/3 Octave Extended, Long Throw, Professional Equalizer
overtones of guitar are intensified in this octave.
Upper Highs: 10KHz to 20KHz
The upper limits of hearing fall within this octave. Since only the upper harmonics of
some instruments are in this range, you may often cut these bands to reduce hiss
without affecting the overall sound quality. Brightness of cymbals and synthesizer
harmonics may also be controlled. Boosting this range can add “air” to the instruments
being equalized.
PA Systems – power amp operating levels
It is common to use 31 band equalizers for FOH (Front of House) as well as monitors.
If the Equalizer is the last piece of equipment before the power amps, there is a risk of
operating at less than optimal levels. While under these conditions, it is common for
power amp level controls to be set to maximum sensitivity. The problem with this
approach is that the operating levels through the equalizer will end up being quite low.
Power amplifiers set to maximum sensitivity results in approximately 0dBu for full
power. Since the system has headroom, the actual operating level could end up being
-20dBu. The XL231 has an extremely high dynamic range of 123dB, yet even under
these conditions, it may be possible to hear noise out of the speakers.
To correct this problem, set the power amplifier input level controls for much less gain.
Reducing the gain of the power amp by 12 to 20 dB will allow increasing the operating
level through the equalizer.
The goal is to have the operating level in the range of the front panel level bars. Rather
than turning the gain controls all the way up on the power amplifier, try setting gain
controls half way up as a start.
Tuning a sound system
What is the best way to use an equalizer to tune a sound system? If you ask 10 sound
engineers the best way to do this, you may get more than 10 different answers. In the
following we discuss two common methods.
There are a number of different ways to tune a room. Some use spectrum analyzers or
other computer based tools to try to measure what the room is doing, and then correct
the response with the equalizer. These are useful methods and allow one to gain insight
into the process.
One aspect that many engineers agree on is that listening is the key. Regardless of the
method used, before they are “done”, they listen to a recording they are very familiar
with and walk around the venue checking for coverage, and overall sound. The final
tweaks to the equalization are determined from this process.
One other item to keep in mind. Acoustic environments change with temperature and
humidity. When doing an evening show after a mid day sound check, one must be
prepared to make adjustments just before the show.
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ART XL 231 Dual 31 Band, 1/3 Octave Extended, Long Throw, Professional Equalizer
Tuning a sound system by ear.
To tune a room by ear also makes sense. Test equipment won’t always indicate what
sounds best. Acoustic environments are very complex and many tradeoffs are made.
System performance can vary quite a bit from one listening position to another. Not only
does frequency response vary, reverb decay times verses frequency can vary also.
The human hearing system is quite complex and often is the best piece of test
equipment when it comes to room tuning.
Select Source Material:
Choose a piece of source material. You may want to experiment with trying different
sources such as:
1) a music CD that uses a lot of the audio spectrum. If the system is being set up for a
particular performer, then a recording of that performer may be a good choice.
2) A music CD that the user is very familiar with.
3) A pink noise generator.
Having multiple sources to experiment with is useful for testing the system.
Step-by-step:
With the system up and running, start with the equalizer set to a flat position. To tune
the room, with source material playing, working on one frequency band’s slider at a
time, move the slider very high so the signal in that band dominates the overall signal.
Listen to what you hear in this band. Slowly decrease the slider to the point where you
can barely hear that band. Then lower it just a bit so the energy in that band gets buried
in all the other sound. Repeat this for each frequency band.
After the first tuning, try different source material and perform the tuning again. As more
tuning is done, the improvements will be smaller and smaller. Stop tuning when the
improvements are very small.
The tendency for users new to this is to end up with all bands boosted by some amount.
Try to learn not to do this. Practice by boosting each band from center and returning it to
center. The way that a single band’s energy disappears in the overall sound is what you
want to train yourself to hear. With practice, you will find room tuning to become easier,
and, quicker.
When tuning is complete, while listening to your source material, switch between
ACTIVE and BYPASS to see what you have done. Set the Level so that the overall level
is approximately the same when in BYPASS or ACTIVE, that is normalized.
Ringing out a Room
Setting an EQ by ringing is useful for increasing the available system gain before
feedback. In a live sound system, with stage monitors and separate front of house
system (FOH), only the monitors should be rung out. This is where feedback is most
likely to occur. The FOH should be equalized for the best overall sound. The ringing
method doesn’t necessarily create the best sound.
To ring out the monitors, if available, use a limiter set to infinite slope, a low threshold,
and, set the level low to save everyone’s ears.
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ART XL 231 Dual 31 Band, 1/3 Octave Extended, Long Throw, Professional Equalizer
Set the equalizer for the monitor channel being set to flat with all of the sliders at their
center detents.
Slowly bring up the microphone gain until feedback occurs. Cut the level of the
frequency band that the feedback occurs in. It takes practice to know which frequencies
are in each band. As soon as the first tone disappears, increase gain more and a new
tone will begin to build. Again, reduce the slider for the corresponding frequency.
Continue this procedure until tones start to come on in multiple frequencies. At this
point, you are probably done. Expect to actually remove from 1 to 4 tones.
Repeat the procedure for the other monitor channels.
Additional adjustments may then be done by taste for best sound or intelligibility.
Please remember, no method is perfect, experiment.
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ART XL 231 Dual 31 Band, 1/3 Octave Extended, Long Throw, Professional Equalizer
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, (A R T) 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 five 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.
A R T 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.
A R T 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.
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ART XL 231 Dual 31 Band, 1/3 Octave Extended, Long Throw, Professional Equalizer
SERVICE
The following information is provided in the unlikely event that your unit requires
service.
1) Be sure that the unit is the cause of the problem. Check to make sure the unit
has power supplied, all cables are connected correctly, and the cables
themselves are in working condition.
2) If you find the unit to be at fault, write down a complete description of the
problem, including how and when the problem occurs. Please write down a
description of your complete setup before calling Customer Service.
3) Contact our Customer Service department at (716) 297-2920 for your Return
Authorization number or questions regarding technical assistance or repairs.
Customer Service hours are 9:30 AM to 5:00 PM Eastern Time, Monday through
Friday.
4) Pack the unit in its original carton or a reasonable substitute. The packing box
is not recommended as a shipping carton. Put 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.
5) Include with your unit: a return shipping address (we cannot ship to a P.O.
Box), a copy of your purchase receipt, a daytime phone number, and a
description of the problem.
6) Ship only your unit (keep your manual!) to:
Yorkville Sound
4625 Witmer Industrial Estates
Niagara Falls, New York 14305
ATTN: REPAIR DEPARTMENT
RA# ____________________
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ART XL 231 Dual 31 Band, 1/3 Octave Extended, Long Throw, Professional Equalizer
XL231 SPECIFICATIONS
EQUALIZER
Bands
Type/Accuracy
Slide Potentiometers
Range
w/Enhanced Cut
Overall Gain Range
2 x 31, 1/3 Octave, ISO Spacing
Constant Q, 3% Center Frequency
45 mm, Positive Center Detent, Metal Shaft, Grounded Center Tap.
(± 6 dB) or (± 12 dB) Selectable
(+6/-9 dB) or (+12/-18 dB) Selectable
Off to +6 dB (sliders centered)
INPUTS
Type
Connectors
Impedance
Maximum Input Level
Active Balanced
3-Pin XLR, TRS ¼” phone, Euroblock
9.4K Ohms Balanced.
+24 dBu, Balanced, ≤1% THD, [EQ and Level centered]
OUTPUTS
Type
Connectors
Impedance
Maximum Level
3-Pin XLR, Euroblock - Active Balanced
TRS ¼” phone - Impedance Balanced
3-Pin XLR, TRS ¼” phone, Euroblock
≤ 200 Ohms
+26 dBu, Balanced, 20-20K Hz, into ≥600 Ohms, ≤1% THD
RFI Input Filters
Bypass Switching
Clip LED Threshold
High Pass Filter
High Trim
Low Trim
Yes
Passive, Relay
3 dB below clipping. Sensed at all gain stages.
10 to 250 Hz – 12dB/Oct
± 4 dB @ 10 KHz
± 4 dB @ 40 Hz
Frequency Response
[EQ and Level centered, HPF fully counter clockwise]
(+0/-0.25 dB 20-20K Hz), (+0/-1 dB 17-50K Hz), (+0/-3 dB 10-80K Hz)
< 0.005%, @ +4 dBu, 20-20K Hz, 22 KHz BW, [EQ and Level centered]
THD+Noise
(typically 0.003% @ 1 KHz)
IM Distortion (SMPTE)
Signal to Noise Ratio
Headroom
Dynamic Range
Channel Separation
Common Mode Rejection
Line Voltage
Input AC Power
< 0.004%, @ +4 dBu, [EQ and Level centered]
≥ 99 dB, Ref. 0 dBu, 22 KHz BW, unweighted, [EQ and Level centered]
+24 dB, Ref. 0 dBu
≥ 123 dB, Ref: +24 dBu, 22 KHz BW
≥ 90 dB @ 1 KHz, +4 dBu
≥ 60 dB @ 1 KHz
95-125 VAC 50/60 Hz
190-250 VAC 50/60 Hz
31 Watts Typical
Construction
All Steel Chassis
Aluminum Front Panel
SIZE
5.25 x 19 x 8 Inches
133 x 483 x 203 mm
WEIGHT
12 lbs. (5.4 kg)
Note: 0 dBu = 0.775 Vrms
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ART XL 231 Dual 31 Band, 1/3 Octave Extended, Long Throw, Professional Equalizer
XL231 Architect's & Engineer's Specification
The graphic equalizer shall be stereo (2 channels). Each channel shall consist of 31 bands centered on
standard ISO frequencies at intervals of 1/3 octave and covering a frequency range of 20Hz to 20KHz.
Individual frequency bands shall be adjusted by linear slide faders with 45mm travel, tactile center detent,
and metal actuator shafts with dust dams. The range of equalization shall be switch selectable to one of
four boost/cut modes; ±12dB, ±6dB, +12/-18dB, or +6/-9dB. The –18dB and –9dB (enhanced) cut modes
shall have a more narrow bandwidth for reduced audible artifacts while performing deep frequency cuts.
The equalizer shall have a gain of unity with all slide faders centered. The equalizer shall provide a rotary
gain control with a range from Off to +6dB. Frequency response shall be +0/-0.25dB 20-20KHz. Hum and
noise shall be less than or equal to –99dBu and SMPTE intermodulation distortion or THD shall be less
than 0.005% @ +4dBu. Total dynamic range shall be greater than or equal to 123dB, referenced to
+24dBu, measured with a 22KHz bandwidth. Input impedance shall be 9.4K Ohms balanced and
maximum input level shall be +24dBu. Output impedance shall be 100 Ohms and maximum output level
into 600 Ohms shall be +26dBu balanced. Inputs and outputs shall be active (transformerless) balanced
type on XLR, ¼” phone, and detachable Euroblock connectors. Individual bandpass filters shall be 3%
precision tolerance constant Q design, with interleaved summing, for minimum filter interaction and
accurate control setting. The filters shall be electrically removed from the circuit in the center (flat) slider
position. The equalizer shall include a 12dB per octave high pass filter tunable from 10Hz to 250Hz, as
well as variable Low Trim and High Trim rotary controls providing ±4dB of gradual boost or cut below and
above 1 KHz respectively. A three color 11 segment LED bar-graph with clip indicator, and peak-hold
readout shall be included on each channel for visual level monitoring. There shall be a unit bypass relay
which shall be activated by power failure or front panel bypass switch on each channel. The equalizer
shall weigh 12 lbs., and mount in a standard 19” EIA rack using 3 spaces (5.25” high x 19” wide x 8”
deep). The power requirement shall be 95-125 VAC, or 190-250 VAC, 50/60 Hz, 31 Watts. Note: 0dBu =
0.775 Vrms. The unit shall be the ART XL231.
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APPLIED RESEARCH & TECHNOLOGY
215 TREMONT STREET
ROCHESTER, NEW YORK 14608 USA
(585) 436-2720 – Voice
(585) 436-3942 – Fax
www.artproaudio.com
E-mail: support@artproaudio.com
Model XL231 - Dual 31 Band, 1/3 Octave Extended, Long Throw, Professional Equalizer
XL-5004-100