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AV25-2-RS232
AV25-2 RS232
Owner’s Manual
January 2012
www.stewartaudio.com
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Important Safety Instructions
Before using your Stewart Audio Inc. Power Amplier, 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 USERSERVICEABLE 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 sufcient 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 amplier is installed or operated. Retain these instructions for future reference. All instructions should be followed; all warnings on the amplier
and in the operating instructions should be adhered to.
CAUTION
RISK OF ELECTRIC SHOCK
DO NOT OPEN
3. The amplier should be situated so that its location and position does not
interfere with its proper ventilation. For example, the amplier must not
be placed on a rug, bed, sofa or similar surface that impedes airow
across the chassis. Airow through the ventilation openings should be
unobstructed.
4. This amplier should not be used near water, for example, near a bathtub,
in a wet basement, near a swimming pool, etc. This amplier is intended
to be operated in a controlled indoor environment.
5. Do not place the amplier near heat sources such as radiators, heat registers, stoves, or other appliances that produce heat.
6. The amplier 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 amplier. To prevent risk of re or injury, damaged cords and cables should be
replaced immediately.
8. Clean the amplier with a clean, damp cloth. Do not use solvents or abrasive cleaners. Never pour any liquid on the amplier.
9. When left unused for a long period of time, the power cord should be
unplugged form the outlet.
10. Damaged Ampliers requiring service should be repaired by a qualied
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 amplier has been exposed to rain or other moisture.
d. The amplier does not appear to operate normally or exhibits
a marked change in performance.
e. The amplier has been dropped or the enclosure
damaged.
11. The user should not attempt to service the amplier beyond that described in the operating instructions. All other servicing should be referred
to qualied service personnel.
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Table of Contents
Important Safety Instructions ······························································ 2
Table of Contents ················································································ 4
1 Welcome ························································································· 5
1.1 Features ··············································································· 5
1.2 Using this Manual ································································ 5
2 Setup ······························································································· 6
2.1 Setup Precautions ······························································· 6
2.2 Amplier Installation ···························································· 6
2.3 Proper Cooling Considerations ············································ 8
2.4 Input Connections ······························································· 9
2.5 Output Connections ·························································· 11
3 Operation ······················································································ 12
3.1 Operation Precautions ······················································· 12
3.2 Controls, Indicators, and Connectors ································ 13
4 RS232 Control ·············································································· 15
4.1 RS232 Overview ································································ 15
4.2 Muting and Memory ························································· 15
4.3 RS232 Commands ···························································· 13
5 Troubleshooting ··········································································· 17
6Technical Specications ······························································· 19
7 Warranty Information ·································································· 20
7.1 Warranty Summary ···························································· 20
7.2 Return Procedure ······························································ 20
8 Notes ····························································································· 23
1 Welcome
Congratulations on the purchase of your new Stewart Audio AV Series
power amplier. This amplier 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 amplier 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 amplier is the result of years of
experience in the design and manufacture of quality ampliers. As such
it provides a combination of performance and operational benets that
simply cannot be found in conventional ampliers.
Sub Compact 1/4 rack package
Two channel amplier, optimized to drive 4
Ohm and 8 Ohm loads
RS232 Control over volume and muting
Music and re alarm muting
Clean full–range dynamic power
Signal Detect trigger for sleep & wake up
Multiple mounting options
Made in the USA
1.2 Using this Manual
In order to obtain maximum performance from your AV Series Amplier, 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 amplier in the most common
scenarios. If you nd 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
2.1 Setup Precautions
CAUTION: Before installing your amplier, make sure that
you have read the Important Safety Precautions at the beginning of this manual.
2.2 Amplier Installation
The AV25-2-RS232 incorporates a number of different mounting options in order to t your installation needs.
2.2.1 Pole-Mounting
The AV Series of ampliers is Stewart Audio’s rst line of polemountable ampliers. The AV25-2-RS232 has mount holes on both the
top as well as the side of the unit which can be used with the AV-Pole
bracket available from Stewart Audio.
Part Number: AV-Pole
2.2.1 Universal-Mount Installation
The AV25-2-RS232 also has a universal bracket available which allows
the unit to be mounted against a wall or under a table. Two screws are
included in the kit which will afx the bracket to the top or the side of
the unit. Once this is done, two holes are available for mounting the
unit where desired.
CAUTION: Use only the screws provided in mounting
brackets to the amplier. Do not overtighten.
Part Number: AV-Bracket
AV25-2-RS232
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2.2.3 Product Dimensions
4.25in
10.8cm
AV25-2-RS232
Front
3.2in
8.1cm
1.25in
3.2cm
2.4 Input Connections
Your AV25-2-RS232 amplier is provided with a 3-pin Phoenix connector for each input. This connector will accept both balanced or unbalanced connections, however some modications must be made for an
unbalanced connection. See the next two sections for instructions on
connecting your amplier to its input source.
2.4.1 Balanced Connections
When using a balanced input source and connector, you must ensure
that the hot, cold, and ground pins of the connector are matched up to
the +, -, and ground pins of the AV25-2-RS232’s Phoenix connector
respectively. Diagrams have been provided for standard XLR and TRS
connectors. Please refer to the manual of your input source in case it
does not follow the standard pin-out.
1.25in
3.2cm
Side
2.3 Proper Cooling Considerations
Because the AV25-2-RS232 regulates its temperature using convection
cooling and no fans, the amplier must be given adequate space to
allow for proper airow. Do not stack the ampliers on top of each other or mount it in a way that other equipment will block airow through
the case.
CAUTION: Inadequate airow to the amplier can cause the
amplier to overheat and potentially become damaged in
the process. Be sure to provide plenty of air space to allow
for convection cooling.
Input Connector
-
+
-
+
Female XLR
Input Connector
-
+
-
+
-
Male TRS
+
+
Ground
(Shield)
(Connector enlarged to show detail)
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2.4.2 Unbalanced Connections
When using an unbalanced input source and connector, a jumper must
be added between the negative (-) terminals and the ground terminals.
Once this has been done, the unbalanced source can be connected to
the positive (+) and ground terminals. Diagrams have been provided for
standard RCA and TS connectors. Please refer to the manual of your
input source in case it does not follow the standard pin-out.
Ground
(Shield)
Male RCA
+
+
+
Ground
(Shield)
Input Connector
-
+
-
+
A jumper has been added between the
negative (
-
) terminals and ground
2.5 Output Connections
Stewart Audio recommends using high-quality, heavy-gauge speaker
wire and connectors to send the output signal of your amplier to the
speakers. Use the following table as a guideline when selecting your
wire gauge.
Speaker leads connect by means of terminal block connectors supplied
with the unit. Strip speaker leads 1/4” and insert into connector observing proper polarity. With a small, at-blade screwdriver, tighten the
screw until the leads are held securely in place. Inspect for possible
shorts or broken wires.
Distance Wire Gauge
Up to 25 ft. 16 AWG
26-40 ft. 14 AWG
41-60 ft. 12 AWG
Ground
(Shield)
Male TS
Input Connector
-
+ - +
Terminal Block Connector
(Rear of AV-25)
+
+
+
Ground
(Shield)
A jumper has been added between the
negative (
-
) terminals and ground
Channel 2
-
+ - +
Channel 1
-
+
-
+
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3 Operation
1
2
36
7 8
4 5
9
1
2
3
6
7
8
4
5
9
3.1 Operating Precautions
1. Before use, your amplier must be congure 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 amplier 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 AV25-2-RS232 or connected equipment
if the instructions in this manual are not followed.
3.2 Controls, Indicators, and Connectors
AV25-2-RS232
PLENUM RATED
+ -
PWR
- + - +
#2 SPEAKER #1
LEVEL
#1
TX
RS232 IN
RX
#2
- + - +
#2 INPUT #1
Speaker Output Connector
RS232 Connector
Power Connector
Channel 2 Level Knob
Channel 1 Level Knob
#2 #1
ON SIG CLIP
Power Indicator LED
Signal Present Indicator LED
Clip Indicator LEDs
Input Connector
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3.2.1 Indicators
The AV 25 has 4 rear panel LED indicators. The rst is the power indicator which will illuminate when power is supplied to the amplier. The
nal light is the signal present LED which will illuminate when signal is
detected on either one of the input connection channels. The nal 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 amplied. To x this, the gain should be reduced at the
preamp or mixer level.
3.2.2 Controls
All AV25-2-RS232 controls are located on the rear of the unit. There is
no power switch so the AV25-2-RS232 will turn on whenever power is
supplied to it. Signal Sense Technology (SST ) will power up the amplier from sleep when a signal is detected. After 5 minutes without
an input signal the amplier will go into sleep mode.
The rear panel contains two individual channel volume knobs . The amplier is set to run off of a line-level source and the level should be adjusted for optimum performance. To adjust this knob, you will need a
small at-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 counter-clockwise, adjust the gain
down at the source level.
3.2.3 RS232 Controls
Please refer to section 4.
4 RS232 Control
4.1 RS232 Overview
The AV25-2-RS232 contains built-in RS232 control over the master volume and master muting of the amplier. Through the use of RS-232
commands, this interface will control an internal digital potentiometer
and mimic the standard 10KΩ potentiometer typically put into a wallplate. The available commands will mute, increase or decrease the volume, or set the volume to a specic value. All communication should
be done at 9600 baud.
4.1 RS232 Connection
6
7
8
(Rear)
DB9 Female
9
NOTE - TX and RX
labelings are relative to
4.2 Muting and Memory
When the device is muted, it will save the current volume so that when
unmuted it will return to the previously set volume.
All volume and mute settings are saved into an internal memory so it
will recover within milliseconds from a power reset (compatible with
ampliers with sleep states).
1
2
3
4
5
the controller
TX
RX
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4.3 RS232 Commands
5 Troubleshooting
Command Names and Description
VOLUME_UP
Increases the volume by 10%
VOLUME_DOWN
Decreases the volume by 10%
VOLUME_DISCRETE
Sets volume to a specic volume (rounded
to nearest 5%).
Range: 0x00 – 0x64 (0 - 100)
MUTE_TOGGLE
Toggles mute between muted and unmated state.
MUTE_FORCE_MUTE
Forces the amplier into a mute state.
MUTE_FORCE_UNMUTE
Forces the amplier into an unmuted state.
STATUS_VOLUME
Returns the current volume.
STATUS_MUTE
Returns the current mute state
FIRMWARE_VERSION
Returns the current version in the format:
0x02 0xXX 0xYY 0x03
(XX = Version, YY = Revision)
If an invalid command is received, the device will respond with:
0x02 0x45 0x52 0x03.
This will appear as ER in a terminal console.
In response to a mute or volume command, the device will respond
with: 0x02 0x76 0xXX 0x03
The 0xXX will be the hex equivalent of the current volume.
Hex Command
0x02 0x76 0x75 0x03
0x02 0x76 0x64 0x03
0x02 0x56 0xXX 0x03
0x02 0x6D 0x4D 0x03
0X02 0x6D 0x79 0x03
0X02 0x6D 0x6E 0x03
0x02 0x76 0x53 0x03
0x02 0x6D 0x53 0x03
0x02 0x44 0x56 0x03
Problem: Power indicator does not turn on.
Procedure: Check that the amplier is plugged into a live outlet. After
you have ensured that it is not a power issue, disconnect any speakers.
If the amplier 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. Ensure signal present LED is
ashing to denote a signal. If there is no signal detected check signal
source and that level controls are set high enough.
Problem: Amplier overheats and/or shuts off.
Procedure: Review section 2.3 on proper cooling procedures. Check
the signal lights on the rear of the amplier to see if the signal is overdriving (the signal light ashes red frequently). Overdriving the amplier
for extended periods of time can cause a thermal shutdown.
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.
.Problem: No RS232 communication
Procedure: Ensure that the connections are done as specied in section 4.2.2. Check that the communication is at 9600 baud. Shorten the
cable lengths to see if it affects the communication
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6 Technical Specications
Maximum Output 30Hz - 20kHz
Stereo 25W @ 8Ω per channel
35W @ 4Ω per channel
Frequency Response (+0, -3 dB) 30Hz-20kHz
Bandwidth +/- 3.0dB 30Hz-30kHz
THD+N <0.1%
Signal to noise ratio >100dB
External Mute 5-12VDC
Slew Rate 30V/ms
Input Sensitivity 0.5V (-3 dBV)
Standard Voltage Gain 28X (26.5dB)
Input Impedance (Balance/Unbalanced) 20k Ohms/10k Ohms
Sleep, Idle Current Draw, 1/8 Draw 0.005/0.01/0.15 Amps
Class D
Input Connectors Euro Block
Output Connectors Euro Block
Power Supply External In-Line 48DVC
Cooling Convection-Cooling
Controls Level
LED Indicators Power, Signal Present &
Clip
Construction Aluminum Chassis
Dimensions
Height 1.25in (3.2cm)
Width 4.35in (11.1cm)
Depth 3.2in (8.1cm)
Weight 0.37bs (0.16kg)
Stewart Audio reserves the rate to change features and specications without notice.
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7 Warranty Information
7.1 Warranty Summary
All Stewart Audio ampliers 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 ampliers 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 amplier was
purchased.
7.1.1 Eligibility Requirements.
Stewart Audio warrants against all malfunctions which come as a result
of component or manufacturer defect. The amplier 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 amplier has been exposed to moisture or extreme tempera-
tures.
The amplier has been dropped, items have been dropped on the
amplier, or the enclosure has been damaged.
The amplier has been opened by the operator.
The amplier 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 amplier 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.
7.2 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.
7.2.1 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.
7.2.2 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 7.2.3.
3. Ship the defective product using a method which provides for order tracking or order conrmation. 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.
7.2.3 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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7.2.3 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 ampliers.
3. When shipping your amplier, 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.
7.2.4 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.
7.2.5 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.
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