Stewart Audio CVA 25-1 User manual

CVA Series
Owner’s Manual
March 2014
1
www.stewartaudio.com

Important Safety Instructions
Before using your Stewart Audio Inc. Power Amplier, please read this
Owner’s Manual carefully to ensure optimum trouble-free perfor-
mance.
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.
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 sufcient mag-
nitude 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 am-
plier is installed or operated. Retain these instructions for future refer-
ence. All instructions should be followed; all warnings on the amplier
and in the operating instructions should be adhered to.
2

3. The amplier should be situated so that its location and position does not
interfere with its proper ventilation. For example, the amplier must not
be placed on a rug, bed, sofa or similar surface that impedes airow
across the chassis. Airow around the unit should be unobstructed.
4. This amplier should not be used near water, for example, near a bathtub,
in a wet basement, near a swimming pool, etc. This amplier is intended
to be operated in a controlled indoor environment.
5. Do not place the amplier near heat sources such as radiators, heat regis-
ters, stoves, or other appliances that produce heat.
6. The amplier’s power supply should only be connected to 120 VAC, 60
Hz power source. 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 ampli-
er. To prevent risk of re or injury, damaged cords and cables should be
replaced immediately.
8. Clean the amplier with a clean, damp cloth. Do not use solvents or abra-
sive cleaners. Never pour any liquid on the amplier.
9. When left unused for a long period of time, the power cord should be
unplugged from the outlet.
10. Damaged Ampliers requiring service should be repaired by a qualied
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 amplier has been exposed to rain or other moisture.
d. The amplier does not appear to operate normally or exhibits
a marked change in performance.
e. The amplier has been dropped or the enclosure
damaged.
11. The user should not attempt to service the amplier beyond that de-
scribed in the operating instructions. All other servicing should be referred
to qualied service personnel.
3

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 Amplier Installation ····························································6
2.2.1 Pole-Mount Installation···········································6
2.2.2 Universal-Mount Installation ···································7
2.2.3 Product Dimensions ··············································· 8
2.3 Proper Cooling Considerations ············································8
2.4 Input Connections ······························································· 9
2.4.1 Balanced Input Connections···································9
2.4.2 Unbalanced Input Connections·····························10
2.5 Output Connections ·························································· 11
2.5.1 Constant Voltage ················································· 11
2.5.2 Wiring Example ···················································· 12
3 Operation ······················································································13
3.1 Operation Precautions ·······················································13
3.2 Controls, Indicators, and Connectors ································14
3.2.1 Indicators ······························································15
3.2.2 Controls ································································15
3.2.3 Remote Volume Control ······································· 15
4 Troubleshooting··········································································· 17
5 Technical Specications ······························································ 18
6 Warranty Information·································································· 19
6.1 Warranty Summary····························································19
6.1.1 Eligibility for Factory Repair ··································19
6.2 Return Procedure ······························································19
6.2.1 Return Authorization ·············································20
6.2.2 Packaging Instructions·········································· 20
6.2.3 Shipping Instructions ············································20
6.2.4 Estimate Approval·················································21
6.2.5 Payment of Non-Warranty Repair·························21
7 Accessories ···················································································22
4

1 Welcome
Congratulations on the purchase of your new Stewart Audio CVA Se-
ries power amplier. This amplier has been designed and built to pro-
vide you with years of high-quality audio performance and trouble-free
operation. If after reading this manual you should have any questions
concerning amplier installation and operation, please contact your Au-
thorized Stewart Dealer, or you may contact us directly using the con-
tact information provided on the back of this manual.
1.1 Features
Your Stewart Audio CVA Series amplier is the result of years of expe-
rience in the design and manufacture of quality ampliers. As such it
provides a combination of performance and operational benets that
simply cannot be found in conventional ampliers.
 Sub Compact 1/4 rack package
 Mono constant voltage amplier (70.7V or 100V)
 Music and re alarm muting
 Clean full–range dynamic power
 Remote volume control
 Multiple mounting options
 External inline power supply
 Made in the USA
1.2 Using this Manual
In order to obtain maximum performance from your CVA Series Ampli-
er, 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 in-
stall and operate your new CVA Series amplier 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 di-
rectly using the contact information provided on the back of this manu-
al.
5

2 Setup
2.1 Setup Precautions
CAUTION: Before installing your amplier, make sure that
you have read the Important Safety Precautions at the be-
ginning of this manual.
2.2 Amplier Installation
The CVA Series incorporates a number of different mounting options in
order to t your installation needs.
2.2.1 Pole-Mount Installation
The CVA Series amplier casing 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. Two screws are included in the kit which
will afx the bracket to the top or side of the unit.
Part Number: AV-Pole
6

2.2.1 Universal-Mount Installation
The CVA Series 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 afx 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 amplier. Do not overtighten.
7

2.2.3 Product Dimensions
2.3 Proper Cooling Considerations
Because CVA Series ampliers regulates their temperature using con-
vection cooling and no fans, the ampliers must be given adequate
space to allow for proper airow. Do not stack the ampliers on top of
each other or mount it in a way that other equipment will block airow
along the surfaces of the case.
CAUTION: Inadequate airow to the amplier can cause the
amplier to overheat and potentially become damaged in
the process. Be sure to provide plenty of air space to allow
for convection cooling.
8

2.4 Input Connections
Your CVA Series amplier is provided with a 3-pin Euro Block connector
for its input connection. This connector will accept both balanced or
unbalanced connections, however some modications must be made
for an unbalanced connection. See the next two sections for instruc-
tions on connecting your amplier to its input source.
2.4.1 Balanced Input 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 CVA Series’ Euro Block connector re-
spectively. 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.
NOTE: The CVA Series of ampliers do not accept TRS in-
puts wired for a stereo source. TRS inputs should only be
used for balanced mono inputs.
9

2.4.2 Unbalanced Input 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. Please refer to the manual of
your input source in case it does not follow the standard pin-out. For
your convenience, pre-wired connectors are available for purchase, see
the next page for details.
NOTE: A jumper is required for connecting an unbalanced
input.
NOTE: The CVA Series of ampliers do not accept stereo
inputs. Either one side must be selected from the stereo
source or an overload-protected Y-cable must be used to
sum them to mono. It is highly recommended that you
purchase the pre-wired connectors mentioned on the next
page. Damage to source equipment can result from the
10

Pre-wired unbalanced connectors are available for purchase from Stew-
art Audio. These will allow for a quicker installation with less room for
error when connecting the CVA Series amplier to an unbalanced
source. The summing adapters will properly sum a stereo source for
use with the mono input on the rear of the amplier without causing
sound cancellation. Part numbers are found below the diagrams.
2.5 Output Connections
Because of the differences in the way that constant-voltage ampliers
work as opposed to a typical 8-ohm setup, the wiring procedure and
the gauge of wire used is very different.
Constant voltage systems and speakers use a smaller current ow than
the typical 8ohm systems and thus can use a higher gauge (thinner
diameter) wire. Please refer to the following g chart to choose the ap-
propriate wire gauge for your installation.
Speaker leads connect by means of removable Euro Block connectors
supplied with the unit. Strip speaker leads 1/4” and insert leads into
connector observing proper polarity. With a small, at-blade screwdriv-
er, tighten the screw until the leads are held securely in place. Inspect
for possible shorts or broken wires.
Distance Wire Gauge
Up to 500ft 22 AWG
500-1000 ft. 20 AWG
Over 1000ft 18 AWG
ADPT-RCA
Mono
Female RCA
ADPT-SUMRCA
Stereo
Female RCA
ADPT-SUM35
Stereo
Female 3.5mm
11

2.5.1 Constant Voltage
The Euro Block connector on the rear of the amplier is capable of sup-
plying output at either 70V or 100V depending on the step-down trans-
formers which will be used in the speaker installation. For information
on specic step-down transformer installation information, please con-
sult the transformer’s manufacturer’s literature.
2.5.2 Wiring Example
The diagram below is a typical wiring setup for two speakers with out-
board step-down transformers wired in parallel to the 70V output op-
tion of a CVA Series amplier.
100V 70V
12

3 Operation
3.1 Operating Precautions
1. Before use, your amplier must be congured for proper opera-
tion, 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 amplier 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 CVA Series amplier or connected equip-
ment if the instructions in this manual are not followed.
NOTE: For additional operating precautions, please refer
to “Important Safety Instructions” located on Page 2.
13

3.2 Controls, Indicators, and Connectors
1
1
2
3
6
7
8
Volume Level Knob
Input Connector
Remote Volume Control
Clip Indicator LED
Power Connector
Output Connector
4
5
Power Indicator LED
Signal Present Indicator LED
PLENUM RATED
ON SIG CLIP
SPEAKER
+ +
+
PWR
100V 70V
RVC
+10V RVC GND MUTE
- +
INPUT
LEVEL
CVA 25-1
1
236
78
45
14

3.2.1 Indicators
CVA Series ampliers have three rear panel LEDs to indicate the status
of the amplier. The blue LED, labeled “ON”, will be lit when the unit
is not in sleep mode. The green LED, labeled “SIG”, will light when an
audio signal is present on the audio input. When the unit is operating
with both green and blue LEDs lit and the audio input signal goes away
or is removed, the green “SIG” LED will go out and the unit will con-
tinue to operate with the blue LED on for approximately 5 minutes be-
fore going into sleep mode. When signal is present and output is going
to the speakers the red LED, labeled “Clip”, will light when the input
signal is too hot. The “LEVEL” control must be adjusted until the CLIP
LED goes out for undistorted sound amplication.
3.2.2 Controls
All CVA Series controls are located on the rear of the unit. There is no
power switch so the amplier will power up into a sleep state when
power is rst applied. The CVA Series Signal Sense Technology (SST™)
will power up the amplier from sleep when a signal is detected. After
5 minutes without an input signal the amplier will go into sleep mode.
The rear panel contains a single volume knob. The amplier is set to
run off of a line-level source and the level should be adjusted for opti-
mum 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 Remote Volume Control
CVA Series ampliers can have their volume remotely controlled (or
muted) via the Euro Block input on the rear of the amplier. The remote
volume control allows the units volume to be controlled through the
use of an external potentiometer which can be located wherever con-
venient for the user. Remote muting is also useful for re-alarm situa-
tions in which all unnecessary sound must be silenced.
NOTE: If the remote volume control connector is utilized,
it will override the volume knob on the rear of the unit.
15

3.2.3 Remote Volume Control (cont.)
In order to remotely control the volume of the unit, a 10k-ohm potenti-
ometer should be placed between the +10V pin and the GND (Ground)
pin on the rear of the unit with its wiper on the RVC pin. The volume
will be determined by the selected resistance on the potentiometer,
the greater the resistance the louder the volume.
The amplier can be remotely muted by making a connection between
the GND pin and the MUTE pin. No power should be applied to these
pins, simply a contact connection.
16

4 Troubleshooting
Problem: Power indicator does not turn on.
Procedure: Check that the unit’s power supply is plugged into a func-
tioning outlet and the power supply is correctly connected to the unit.
Ensure that there is an audio signal present on the audio input indicated
by the green LED being lit. If the unit is powered up but in sleep mode
(due to no signal), the blue power LED will not be lit.
Problem: No output heard on speakers; Blue 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
lit to denote a signal. If there is no signal detected check signal source
and that level controls are set high enough.
Problem: Amplier overheats and/or shuts off.
Procedure: Review section 2.3 on proper cooling procedures. Check
the clip LED on the rear of the amplier to see if the signal is overdriv-
ing (the signal light ashes red frequently). Overdriving the amplier 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 ser-
vice.
17

5 Technical Specications
18
Maximum Output 30Hz - 20kHz
CVA-25 25W @ 70.7V/100V
CVA-50 50W @ 70.7V/100V
Frequency Response (+0, -3 dB) 100Hz—20kHz
Power Bandwidth +/- 3dB 80Hz-30kHz
THD+N <0.1%
Signal-to-Noise Ratio >80dB
Remote Volume Control 0-10V DC, 4-pin Block
Input Sensitivity .5V (-3 dBV)
Standard Voltage Gain 151X (43dB) @ 70.7V
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 3-pin, 3.5mm
Output Connectors Euro Block 2-pin, 5mm
Power Supply External In-Line 48DVC
Cooling Convection-Cooling
Controls Level
LED Indicators Power, Signal, Clip
Construction Aluminum Chassis
Plenum Rating UL 2043 Approved
Dimensions
Height 1.25in (3.2cm)
Width 4.35in (11.1cm)
Depth 3.2in (8.1cm)
Weight CVA-25/CVA-50 <0.7bs (0.32)/
1.2 lbs (0.54kg)
Stewart Audio reserves the rate to change features and specications without notice.

6 Warranty Information
6.1 Warranty Summary
All Stewart Audio ampliers 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 ampliers and accessories must have been purchased through an
authorized Stewart Audio dealer and submitted by the original purchas-
er. This warranty is only valid in the country in which the amplier was
purchased.
6.1.1 Eligibility Requirements.
Stewart Audio warrants against all malfunctions which come as a result
of component or manufacturer defect. The amplier 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 amplier has been exposed to moisture or extreme tempera-
tures.
 The amplier has been dropped, items have been dropped on the
amplier, or the enclosure has been damaged.
 The amplier has been opened by the operator.
 The amplier 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 amplier which are not covered under this
warranty can be factory-repaired at cost to the customer. Use the con-
tact 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.
19

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 [phone] or via e-mail at [email protected]m.
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 mer-
chandise 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 or-
der tracking or order conrmation. 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 ser-
vice center, these instructions must be followed in order to ensure safe
delivery. If they are not followed, Stewart Audio assumes no responsi-
bility for damaged goods and/or accessories that are sent with your
unit.
20