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Power
AV Series
AV Series
AV-50-2
AV-50-2
AV-50
Owner’s Manual
February 2010
www.stewartaudio.com
Clip
Power
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Important Safety Instructions
Before using your Stewart Audio Inc. Power Amplifier, please read this
Owner’s Manual carefully to ensure optimum trouble-free performance.
WARNING: TO REDUCE THE RISK OF ELECTRICAL SHOCK, DO NOT EX-
POSE THIS AMPLIFIER TO RAIN OR MOISTURE. DANGEROUS HIGH
VOLTAGES ARE PRESENT INSIDE THE ENCLOSURE. DO NOT OPEN THE
CABINET. REFER SERVICING TO QUALIFIED PERSONNEL ONLY.
CAUTION: TO REDUCE THE RISK OF ELECTRIC SHOCK,
DO NOT REMOVE COVER (OR BACK). NO USER-
SERVICEABLE PARTS INSIDE. REFER SERVICING TO
QUALIFIED SERVICE PERSONNEL.
The lighting bolt within arrowhead symbol, within an
equilateral triangle, is intended to alert the user to the
presence of un-insulated “dangerous voltage” within
the product’s enclosure that may be of sufficient magnitude to constitute a risk of electrical shock to person.
The exclamation point within an equilateral triangle, is
intended to alert the user to the presence of important
operating and maintenance (servicing) instruction in the
literature accompanying the appliance.
Important Safety Instruction – Please Read Prior to Product
Installation.
1. Installation should be performed by a trained and licensed professional to
insure safe and lasting operation.
2. All of the safety and operating instructions should be read before the amplifier is installed or operated. Retain these instructions for future reference. All instructions should be followed; all warnings on the amplifier
and in the operating instructions should be adhered to.
CAUTION
RISK OF ELECTRIC SHOCK
DO NOT OPEN
3. The amplifier should be situated so that its location and position does not
interfere with its proper ventilation. For example, the amplifier must not
be placed on a rug, bed, sofa or similar surface that impedes airflow
across the chassis. Airflow through the ventilation openings should be
unobstructed.
4. This amplifier should not be used near water, for example, near a bathtub,
in a wet basement, near a swimming pool, etc. This amplifier is intended
to be operated in a controlled indoor environment.
5. Do not place the amplifier near heat sources such as radiators, heat registers, stoves, or other appliances that produce heat.
6. The amplifier should only be connected to 120 VAC, 60 Hz power supply.
Do not defeat the ground or polarization of the power plug.
7. Route power cord and other cables so that they are not likely to be
walked on, tripped over or stressed. Pay particular attention to condition
of cords and cables at plugs and at the point where they exit the amplifier. To prevent risk of fire or injury, damaged cords and cables should be
replaced immediately.
8. Clean the amplifier with a clean, damp cloth. Do not use solvents or abrasive cleaners. Never pour any liquid on the amplifier.
9. When left unused for a long period of time, the power cord should be
unplugged form the outlet.
10. Damaged Amplifiers requiring service should be repaired by a qualified
service technician when:
a. The power cord or AC plug has been damaged.
b. Objects have fallen, or liquid has spilled into the unit.
c. The amplifier has been exposed to rain or other moisture.
d. The amplifier does not appear to operate normally or exhibits
a marked change in performance.
e. The amplifier has been dropped or the enclosure
damaged.
11. The user should not attempt to service the amplifier beyond that described in the operating instructions. All other servicing should be referred
to qualified service personnel.
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Table of Contents
Important Safety Instructions ······························································ 1
Table of Contents ················································································ 3
1 Welcome ························································································· 4
1.1 Features ··············································································· 4
1.2 Using this Manual ································································ 4
2 Setup ······························································································· 5
2.1 Setup Precautions ······························································· 5
2.2 Amplifier Installation ···························································· 5
2.2.1 Pole-Mount Installation ··········································· 5
2.2.2 Rack-Mount Installation ·········································· 6
2.2.3 Product Dimensions ··············································· 6
2.3 Proper Cooling Considerations ············································ 7
2.4 Input Connections ······························································· 7
2.5 Output Connections ···························································· 8
2.6 Wiring Configurations ·························································· 8
2.6.1 Dual-Mode Operation ············································· 8
2.6.2 Single-Mode Operation ········································· 10
2.6.3 Bridge-Mono Operation ········································ 11
3 Operation ······················································································ 13
3.1 Operation Precautions ······················································· 13
3.2 Controls, Indicators, and Connectors ································ 13
3.2.1 Indicators ······························································ 14
3.2.2 Controls ································································ 14
4 Troubleshooting ··········································································· 15
5 Technical Specifications ······························································ 16
6 Warranty Information ·································································· 17
6.1 Warranty Summary ···························································· 17
6.1.1 Eligibility for Factory Repair ·································· 17
6.2 Return Procedure ······························································ 17
6.2.1 Return Authorization ············································· 18
6.2.2 Packaging Instructions ·········································· 18
6.2.3 Shipping Instructions ············································ 18
6.2.4 Estimate Approval ················································· 19
6.2.5 Payment of Non-Warranty Repair ························· 19
This amplifier proudly designed and manufactured in the USA.
1 Welcome
Congratulations on the purchase of your new Stewart Audio AV Series
power amplifier. This amplifier has been designed and built to provide
you with years of high-quality audio performance and trouble-free operation. If after reading this manual you should have any questions concerning amplifier installation and operation, please contact your Authorized Stewart Dealer, or you may contact us directly using the contact
information provided on the back of this manual.
1.1 Features
Your Stewart Audio AV Series amplifier is the result of years of experience in the design and manufacture of quality amplifiers. As such it
provides a combination of performance and operational benefits that
simply cannot be found in conventional amplifiers.
Switching Power Supply—for efficiency, size reduction, depend-
ability
Superior Thermal Protection—effective protection with no noisy
fan and no untimely shutdowns
Full Complimentary Class A/B Amplifier—utilizes integrated Dar-
lington Pairs.
High Dissipation Output Devices—insures operation well within
their S.O.A. (Safe Operating Area) for effortless operation and
device longevity
1.2 Using this Manual
In order to obtain maximum performance from your AV Series Amplifier, please take time to read this brief owner’s manual and carefully
follow the guidelines for connection and operation.
This manual provides you with the information necessary to safely install and operate your new AV Series amplifier in the most common
scenarios. If you find yourself requiring additional assistance, please
feel free to contact your Authorized Dealer, or you may contact us directly using the contact information provided on the back of this manual.
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2 Setup
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AV Series
AV-50-2
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AV Series
AV-50-2
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AV Series
AV-50-2
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AV Series
AV-50-2
2.1 Setup Precautions
CAUTION: Before installing your amplifier, make sure that
you have read the Important Safety Precautions at the beginning of this manual.
2.2 Amplifier Installation
2.2.1 Pole-Mount Installation
The AV 50 amplifier is the first amplifier in the Stewart Audio family of
amplifiers to have the option of pole-mounting. This provides a secure
and convenient way to provide quality sound reinforcement for other
pole-mounted equipment including video projectors.
Using the optional pole-mount kit (Part Number: AV-Pole), secure the
amplifier as shown in the following diagrams.
CAUTION: Use only the screws provided in mounting
brackets to the amplifier. Do not overtighten.
AV-50-2
AV Series
Power
Clip
Power
Clip
AV-50-2
AV Series
2.2.2 Rack-Mount Installation
The AV 50 may also be rack-mounted in a standard 19” (48.3cm) equipment rack using the optional rack-mount kit (Part Number: RMK-50-S).
The amplifier takes up 1U (1.75”) of vertical space.
CAUTION: Use only the screws provided in mounting
brackets to the amplifier. Do not overtighten.
AV-50-2
AV Series
Power
Clip
Part Number: RMK-50-S
2.2.3 Product Dimensions
8.5in
21.6cm
AV Series
7.0in
17.8cm
Side View
AV-50-2
Clip
Power
1.7in
4.4cm
1.7in
4.4cm
Part Number: AV-Pole
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2.3 Proper Cooling Considerations
Because the AV 50 regulates its temperature using convection cooling
and no fans, the amplifier must be given adequate space to allow for
proper airflow. Do not stack the amplifiers on top of each other or
mount it in a way that other equipment will block airflow through the
case.
CAUTION: Inadequate airflow to the amplifier can cause the
amplifier to overheat and potentially become damaged in
the process. Be sure to provide plenty of air space to allow
for convection cooling.
2.4 Input Connections
The AV 50 allows for two different type of unbalanced input connections (RCA and 3.5mm TRS) to be used for the input signal. However,
only one input type may be used at a time.
RCA, or phono connections allow for mono inputs to be connected to
each of the two channels. These inputs are unbalanced and should be
wired as shown in the following diagram.
+
+/Ch 1
-/Ch 2
Ground
(Shield)
+
Ground
(Shield)
+/Ch 1
-/Ch 2
Ground
(Shield)
Ground
(Shield)
A single 3.5mm TRS (stereo) connector will allow for two unbalanced
signals to be sent to the amplifier using only one cable. The tip of the
connector (the left channel) will be sent to Channel 1. The ring of the
connector (the right channel) will be sent to Channel 2. Please refer to
the following diagram for wiring instructions.
2.5 Output Connections
Stewart Audio recommends using high-quality, heavy-gauge speaker
wire and connectors to send the output signal of your amplifier to the
speakers. Use the following table as a guideline when selecting your
wire gauge.
Distance Wire Gauge
Up to 25 ft. 16 AWG
26-40 ft. 14 AWG
41-60 ft. 12 AWG
Over 60 ft. 10 AWG
Speaker leads connect by means of “Phoenix” type block connectors
supplied with the unit. Strip speaker leads 1/4” and insert into connector observing proper polarity. With a small, flat-blade screwdriver,
tighten the screw until the leads are held securely in place. Inspect for
possible shorts or broken wires.
2.6 Wiring Configurations
2.6.1 Dual Mode
Your Stewart AV-Series amplifier is factory-configured to work as a dual
-mode (stereo) amplifier. This allows the amplifier to power two speakers with independent source inputs and gains.
Input Connections
If using RCA (phono) input connectors, connect them to the Channel 1 and
Channel 2 inputs on the rear of the amplifier. If using the 3.5mm TRS connector, connect it to the appropriate socket.
Do not connect a signal to both inputs as this could cause damage to
your amplifier.
Output Connections
Prepare the speaker leads as described in section 2.5. The speaker
leads should be attached to the Phoenix block connector with regard to
their polarity. See diagram for further clarification.
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2.6.1 Dual-Mode Operation (cont.)
Slide the rear-panel switch marked Bridge/Mono/Stereo to the Stereo
position. Be sure the power button is off (out), then plug the line cord
into a grounded AC outlet.
The amplifier is now ready for Dual-mode operation.
Dual-Mode Wiring Setup
Input Stage
Channel 2
Channel 1
- OR -
Output Stage
Phoenix-Style Connector
(Rear of AV50)
Stereo In
2.6.2 Single-Mode Operation
Your Stewart AV-Series amplifier may also be configured for Mono
Operation. This allows the amplifier to power two speakers with independent gain settings using only one input.
Input Connection
The input signal should be connected to Channel 2 if using the RCA
(phono) connectors. Nothing should be connected to Channel 1. If using the 3.5mm stereo input, the right (ring) channel’s signal will be
used.
Output Connections
Prepare the speaker leads as described in section 2.5. The speaker
leads should be attached to the Phoenix block connector with regard to
their polarity. See diagram for further clarification.
The amplifier is now ready for Single-mode operation.
Single-Mode Wiring Setup
Channel 2
+
+ - - +
-
Channel 1
-
+
Channel 2
Channel 1
NOT USED
Channel 2
Input Stage
- OR -
Output Stage
Phoenix-Style Connector
(Rear of AV50)
+ - - +
*Note: Only the right channel (tip) will be used
Stereo In
Channel 1
+
-
-
+
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2.6.3 Bridge-Mono Operation
Your Stewart AV-Series amplifier has the option to run as a dual-mode
(stereo) channel amplifier as well as a more powerful single (mono)
channel amplifier. This mode is known as bridge-mono and requires a
different wiring setup than stereo or mono operation. The difference
between standard mono operation is that the amplifier will only be
powering one speaker. This allows for more wattage (100W @ 8Ω) to
be provided to a single output channel.
Input Connections
The input signal in bridge-mono mode should be connected to Channel
2 if using RCA inputs. Do not connect any input to Channel 1 of the
amplifier. If using the 3.5mm stereo input, the right (ring) channel’s signal will be used.
Output Connections
Prepare the speaker leads as described in section 2.5. The speaker
leads should be attached to the positive terminals of both channels
(terminals 1 and 4). Nothing should be attached to speaker terminal 2
and 3. See diagram for further clarification.
Put Amplifier into Bridge-Mono Mode
Slide the rear-panel switch marked Bridge/Mono/Stereo to the Bridge
position. Be sure the power button is off (out), then plug the line cord
into a grounded AC outlet.
The amplifier is now ready for Bridge-mode operation.
CAUTION: To prevent loudspeaker damage, ensure that
the speaker is rated for the higher-wattage output supplied in Bridge-Mono mode.
Channel 2
Channel 1
Bridge-Mono Wiring Setup
Input Stage
- OR -
NOT USED
Output Stage
Phoenix-Style Connector
(Rear of AV50)
+ - - +
DO NOT USE
+
*Note: Only the right channel (tip) will be used
Stereo In
-
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3 Operation
120VAC 60Hz
LEVEL
12
#2 - SPKR - #1
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AV-50-2
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2
3
4
6
5
7
8
9
1
2
3
4
5
6
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3.1 Operating Precautions
1. Before use, your amplifier must be configure for proper operation,
including input and output wiring hookup. Improper wiring can result in damage to equipment or potentially harm to the operator.
Consult section 2 for setup instructions.
2. Tampering with the circuitry, or making unauthorized changes is
not only dangerous but may also violate local regulations.
3. Use care when making connections between the amplifier and the
input or output equipment. Using equipment that is not capable of
handling the output wattage may lead to permanent damage.
NOTE: Stewart Audio will not be held responsible for damage to your AV 50 or connected equipment if the instructions in this manual are not followed.
Controls, Indicators, and Connectors
3.2.1 Indicators
The AV50 has 3 front panel LED indicators. The first is the power indicator which will illuminate when power is supplied to the amplifier. The
next 2 LED indicators are the “Clip” indicators, one for each channel.
These lights will indicate that the input signal is too “hot” and will
sound distorted when amplified. To fix this, the gain should be reduced
at the preamp or mixer level.
3.2.2 Controls
The AV 50’s front panel has only one control, a push button to control
the power of the unit. When the push button is depressed, the power
is on. When the button is push button is out, the power is off.
The rear panel contains two input sensitivity knobs as well as a mode
switch. The amplifier is set to run off of a line-level source and the sensitivity should be adjusted for optimum performance. To adjust this
knob, you will need a small flat-head screwdriver. While a typical program source level is present, spin the rotary knob as far clockwise as
you can without hearing distortion or without the “Clip” indicator illuminating. If the signal is distorting and the knob is all the way counterclockwise, adjust the gain down at the source level.
Front View
AV Series
AV-50-2
The mode switch on the rear of the amplifier should only be adjusted
during the primary installation. It switches the amplifier between the
three output modes: Stereo, Mono, and Bridge-Mono. Refer to section
2.6 of this manual for more information.
Power
Clip
Clip indicator light
Power on/o switch
Power indicator light
Rear View
120VAC 60Hz
Power cable socket (IEC C13)
Channel volume knobs
Speaker mode switch
LEVEL
BRIDGE MONO STEREO
13 14
2
INPUT
STEREO
1
IN
#2 - SPKR - #1
RCA (phono) channel inputs
Stereo 3.5mm input
Speaker outputs (Phoenix-tYpe connector)
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4 Troubleshooting
Problem: Power indicator does not turn on.
Procedure: Check that the amplifier is plugged into a live outlet and
that the power switch is in the down position After you have ensured
that it is not a power issue, disconnect any speakers. If the amplifier
turns on after a few seconds delay, then the problem is in the output
connection. Check wiring and speakers for short circuits.
Problem: No output on one or both channels; Power indicator is
lit.
Procedure: Check that level controls are not turned down. Check that
input and output connections are secure. Check that the mode switch
(Stereo, Mono, Bridge) is in the correct mode.
Problem: Output sound is distorted or cracking.
Procedure: Check all cables for damage or loose connections and re-
duce the gain on the input signal at the mixer or preamp level. Replace
the cables and loudspeakers temporarily to see if this resolves the
problem. If problem still exists, contact your Authorized Dealer for service.
If after reading this troubleshooting section you are unable to restore
proper function, return it to your Authorized Dealer for service. Refer to
section 6 for instructions.
5 Technical Specifications
Maximum Output, 20Hz - 20kHz
Stereo 25W @ 8Ω per channel
50W @ 4Ω per channel
Bridged Mono 100W @ 8Ω
Frequency Response +/- 0.5dB, 1W
Bandwidth +/- 3.0dB
Noise (A weighted, any mode)
THD (8Ω) 20Hz-20kHz
Input Impedance
Input Sensitivity for Rated Output (8Ω)
Slew Rate (Stereo Mode)
Damping Factor
Number of Channels
Input Connectors
Output Connectors
Power Requirements (8Ω/channel)
Power Supply Design
Dimensions
Height 1.7in (4.4cm)
Width 8.5in (21.6cm)
Depth 7.0in (17.8cm)
Weight 2.8lbs (1.6kg)
Stewart Audio reserves the rate to change features and specifications without notice.
30Hz-20kHz
10Hz-50kHz
>100dB
<0.1%
10kΩ
1V
>30V/ms
>200/8Ω
2
RCA, 3.5mm TRS
Phoenix Block
120V AC 100W
High-speed Switching
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6 Warranty Information
6.1 Warranty Summary
All Stewart Audio amplifiers and accessories, unless excluded in this
summary, are covered by a 3-year limited warranty on parts and labor
from the data of purchase. In order to be eligible for warranty repairs,
the amplifiers and accessories must have been purchased through an
authorized Stewart Audio dealer and submitted by the original purchaser. This warranty is only valid in the country in which the amplifier
was purchased.
6.1.1 Eligibility Requirements.
Stewart Audio warrants against all malfunctions which come as a result
of component or manufacturer defect. The amplifier is also covered
from all failures which arise during the warranty period (3 years from
date of purchase) that are not a result of misuse. The following actions
will void your warranty:
The power cord or AC plug has been damaged through misuse.
The amplifier has been exposed to moisture or extreme tempera-
tures.
The amplifier has been dropped, items have been dropped on the
amplifier, or the enclosure has been damaged.
The amplifier has been opened by the operator.
The amplifier was improperly packaged when sending to the fac-
tory for repair, resulting in damage.
Any of the precautions or instructions found in this manual were
not followed.
Damages resulting to the amplifier which are not covered under this
warranty can be factory-repaired at cost to the customer. Use the contact information below to initiate the repair process.
6.2 Return Procedure
This section includes the return procedures which must be followed in
order to prevent processing delay or cost to the customer. Please read
the entire section before contacting Stewart Audio for returns.
6.2.1 Return Authorization Number
All returns to the factory for service must be accompanied by a Return
Authorization (RA) number. One can be obtained by contacting Stewart
Audio at (209) 588-8111 or via e-mail at support@stewartaudio.com.
NOTE: Any defective products received without an RA number
will be returned to sender at their expense.
If Stewart Audio is unable to contact the sender in 14 days, the merchandise will be considered scrap and may be disposed of.
6.2.2 Shipment Instructions
If Stewart Audio requests that you ship the defective product back to
their service center, please refer to the guide below. To ensure prompt
warranty service, be sure to follow all instructions.
1. Return Authorization (RA) is required for product being sent to the
factory for service.
2. See packing instructions in section 6.2.3.
3. Ship the defective product using a method which provides for order tracking or order confirmation. The service center is located at
the following address:
Stewart Audio
14397 Cuesta Court Suite D1
Sonora, CA 95370
4. Use a bold black marker and write the RA number on three sides
of the box.
5. Record the RMA number for future reference. The RA number can
be used to check the repair status.
6.2.3 Packaging Instructions
Should Stewart Audio request that you ship your product to their service center, these instructions must be followed in order to ensure safe
delivery. If they are not followed, Stewart Audio assumes no responsibility for damaged goods and/or accessories that are sent with your
unit.
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6.2.3 Packaging Instructions (cont.)
1. Please write the RA number on three sides of the box. Include the
Stewart Audio RA number inside the box and a brief description of
the problem.
2. Do not ship any accessories (manuals, cords, hardware, etc.) with
your unit. These items are not needed to service your product.
Stewart Audio will not be held responsible for these items if they
are returned with the amplifiers.
3. When shipping your amplifier, it is important that it has adequate
protection. We recommend you use the original packing material
when returning the product for repair. If you do not have the original box, see number 4.
4. If you provide your own shipping pack, the minimum recommended requirements for materials are as follows:
a. 275 P.S.I. burst test, Double-Wall carton that allows for 2-
inch solid Styrofoam on all six sides of unit or 3 inches of
plastic bubble wrap on all six sides of unit.
b. Securely seal the package with an adequate carton sealing
tape.
c. Do not use light boxes or “peanuts”.
NOTE: Damage caused by poor packaging will not be covered
under warranty.
6.2.4 Estimate Approval
An estimate for all non-warranty repairs will be provided to the customer once the unit has been shipped to the factory. The customer is
responsible to approve this estimate within 7 days. If the repairs are
not approved within 14 days, Stewart Audio reserves the right to consider the unit scrap and may discard it.
6.2.5 Payment of Non-Warranty Repairs
Payment for non-warranty repairs must be submitted to Stewart Audio
before the product will be returned to the customer.
Stewart Audio Product Line
Sub-Compact Products
AV 25-2
DA70-2 70W x 2 @ 4 Ohms
35W x 2 @ 8 Ohms
DA70-4 70W x 4 @ 4 Ohms
35W x 4 @ 8 Ohms
DA770-2 80W x 2 Constant Voltage
70.7V rms out
World 600 190W x 2 @ 4 Ohms
110W x 2 @ 8 Ohms
World 1.2 350W x 2 @ 4 Ohms
200W x 2 @ 8 Ohms
World 1.6 550W x 2 @ 4 Ohms
300W x 2 @ 8 Ohms
World 2.1 650W x 2 @ 4 Ohms
400W x 2 @ 8 Ohms
35W x 2 @ 4 Ohms
25W x 2 @ 8 Ohms
CVA 25-1
CVA 50-1
PA50B 50W x 2 @ 4 Ohms
25W x 2 @ 8 Ohms
100W x 1 @ 8 Ohms bridged
PA100B 90W x 2 @ 4 Ohms
50W x 2 @ 8 Ohms
180W x 1 @ 8 Ohm bridged
AV50 50W @ 4 Ohms
25W @ 8 Ohms
100W @ 8 Ohms bridged
PA100B
CVA7400 200W x 2 Constant Voltage
70.7V rms out
CVA7800 400W x 2 Constant Voltage
70.7V rms out
World 600R Recessed controls
World 1.2R Recessed controls
Custom Amps Contact factory
For more information, contact
sales@stewartaudio.com
25W x1 @ 25V/70V
50W x1 @ 25V/70V
19 20
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