Crown VCA-MC4A Manual de usuario
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use of this product, please contact your local Crown Distributor. If you need assistance locating
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This manual does not include all of the details of design, production, or variations of the equip-
ment. Nor does it cover every possible situation which may arise during installation, operation or
maintenance.
The information provided in this manual was deemed accurate as of the publication date. However,
updates to this information may have occurred. To obtain the latest version of this manual, please
visit the Crown website at www.crownaudio.com.
Trademark Notice:
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Some models may be exported under the name Amcron.®
VCA-MC Series Operation Manual
VCA-MC8
1-VCAP 4-VCAP
135504-5
5/08
VCA-MC4A
©2008 Crown Audio®Inc., 1718 W. Mishawaka Rd., Elkhart, IN 46517-9439 U.S.A.
Telephone: 574-294-8000
VCA-MC Series Amplifier Accessories
page 2 Operation Manual
The information furnished in this manual does not include all of the details of design, pro-
duction, or variations of the equipment. Nor does it cover every possible situation which
may arise during installation, operation or maintenance. If you need special assistance
beyond the scope of this manual, please contact Crown Technical Support.
Crown Technical Support
1718 W. Mishawaka Rd., Elkhart, Indiana 46517 U.S.A.
Phone: 800-342-6939 (North America, Puerto Rico and Virgin Islands) or 574-294-8200
Fax: 574-294-8301 Internet: http://www.crownaudio.com
FCC COMPLIANCE NOTICE
This device complies with part 15 of the FCC rules. Operation is subject to the following two
conditions: (1) This device may not cause harmful interference, and (2) this device must accept
any interference received, including interference that may cause undesired operation.
CAUTION: Changes or modifications not expressly approved by the party responsible for com-
pliance could void the user’s authority to operate the equipment.
NOTE: This equipment has been tested and found to comply with the limits for a Class B digital
device, pursuant to part 15 of the FCC Rules. These limits are designed to provide reasonable
protection against harmful interference in a residential installation. This equipment generates,
uses, and can radiate radio frequency energy and, if not installed and used in accordance with
the instruction manual, may cause harmful interference to radio communications. However,
there is no guarantee that interference will not occur in a particular installation. If this equip-
ment does cause harmful interference to radio or television reception, which can be determined
by turning the equipment off and on, the user is encouraged to try to correct the interference by
one or more of the following measures:
• Reorient or relocate the receiving antenna.
• Increase the separation between the equipment and receiver.
• Connect the equipment into an outlet on a circuit different from that to which the receiver is
connected.
• Consult the dealer or an experienced radio/TV technician for help.
WARNING
TO REDUCE THE RISK OF ELECTRIC
SHOCK, DO NOT EXPOSE THIS
EQUIPMENT TO RAIN OR MOISTURE!
WATCH FOR THIS SYMBOL. The exclamation point triangle is used to alert
the user to important oprating or maintenance instructions.
page 3
VCA-MC Series Amplifier Accessories
Operation Manual
Table of Contents
Important Safety Instructions .........................................................2
1 Welcome ...................................................... 5
1.1 VCA Module Features ........................................................ 6
1.2 1-VCAP Level Control Features .........................................6
1.3 4-VCAP Level Control Features .........................................6
2 How to Use This Manual .................................... 6
3 Setup
.......................................................... 7
3.1 Wiring to the 1-VCAP or 4-VCAP Wall-Mount Control ......7
3.2 Wiring Your Own Potentiometer ..........................................8
3.3 Wiring to an External Variable DC Voltage Source .............8
3.4 Bridge-Mono Wiring ..........................................................9
4 Operation ..................................................... 10
4.1 Operation Using the VCAP Wall-Mount Level Control ........ 10
4.1.1 Troubleshooting .........................................................11
4.2 Operation UsingYour Own Potentiometer or an
External 10 VDC Variable Source ........................................12
4.2.1 Troubleshooting .........................................................12
5 Theory of Operation ......................................... 13
6 Specifications ................................................ 14
7 Service . ...................................................... 15
7.1 International and Canada Service ........................................15
7.2 US Service ..........................................................................15
7.2.1 Service at a US Service Center ...................................15
7.2.2 Factory Service ...........................................................15
7.2.3 Factory Service Shipping Instructions ........................16
7.2.4 Packing Instructions....................................................16
7.2.5 Estimate Approval........................................................17
7.2.6 Payment of Non-Warranty Repairs...............................17
8 Warranty ...................................................... 18
Crown Factory Service Information Form ......................................21
VCA-MC Series Amplifier Accessories
page 4 Operation Manual
Illustrations
Figure 1.1 VCA-MC4A Module ..................................................... 5
Figure 1.2 VCA-MC8 Module .......................................................5
Figure 1.3 1-VCAP Wall-Mount Level Control ..............................5
Figure 1.4 4-VCAP Wall-Mount Level Control...............................5
Figure 3.1 Wiring the VCA Level Control to the VCA-MC module. 7
Figure 3.2 Wiring Your Own Potentiometer ................................... 8
Figure 3.3 Example Showing VCA1 and VCA2 Tied Together ........ 9
Figure 5.1 System Block Diagram ................................................ 13
Tables
Table 1. Attenuation per Detent of Crown VCAP Level Control........11
page 5
VCA-MC Series Amplifier Accessories
Operation Manual
1 Welcome
The VCA-MC (VCA multichannel module) is an optional accessory module for the CTs
4200 or CTs 8200 power amplifier. The module provides independent remote level control
for each channel. VCA-MC4A (Figure 1.1) is the VCA module for the CTs 4200. VCA-
MC8 (Figure 1.2) is the VCA module for the CTs 8200.
Four-pin removable Phoenix-style barrier connectors provide the +10 VDC control voltage,
ground, and control inputs for two amplifier channels. Thus, the 4-channel CTs 4200 uses
two connectors; the 8-channel CTs 8200 uses four connectors. The control inputs are
labeled VCA1 (for channel 1), VCA2 (for channel 2), and so on.
VCA-MC modules can be controlled in one of two ways:
• Optional Crown 1-VCAP or 4-VCAP wall-mount level controls
• An external control voltage of 0 to 10 VDC
1-VCAP: See Figure 1.3. Used in conjunction with a VCA-MC module, this is a single-
gang panel with one potentiometer that provides remote volume control for one or more
CTs amplifier channels. The potentiometer on the panel is wired directly to the VCA con-
nectors on the VCA-MC.
4-VCAP: See Figure 1.4. This is a two-gang panel with four potentiometers that provide
remote volume control for four or more CTs amplifier channels. The potentiometers on the
panel are wired directly to the VCA connectors on the VCA-MC.
Figure 1.3
1-VCAP Wall-Mount
Level Control
Figure 1.4
4-VCAP Wall-Mount
Level Control
Figure 1.1
VCA-MC4A Module
Figure 1.2
VCA-MC8 Module
VCA-MC Series Amplifier Accessories
page 6 Operation Manual
1.1 VCA Module Features
• Provides independent remote level control for each channel of a Crown CTs 4200 or CTs
8200 power amplifier.
• Four-pin removable Phoenix-style barrier connectors provide the +10 VDC control
voltage, ground, and control inputs for two amplifier channels.
• Can be controlled by Crown VCAP wall-mount level controls or external DC source
(0 to 10 VDC).
• Any number of control inputs can be electronically tied together to control several chan-
nels from one VCAP or 10VDC voltage source.
• 0 dB attenuation default. If nothing is connected to a control input, the VCA module
defaults to unity gain.
• VCA gain element is in series with amplifier attenuator, allowing the maximum gain of
the system to be set at the amplifier.
1.2 1-VCAP Level Control Features
• Provides remote volume control for one or more CTs amplifier channels.
1.3 4-VCAP Level Control Features
• Provides remote volume control for four or more CTs amplifier channels.
2 How to Use This Manual
This manual provides you with the necessary information to safely and correctly set up and
operate your amplifier accessory. It does not cover every aspect of installation, setup or
operation that might occur under every condition. For additional information, please con-
sult Crown’s Amplifier Application Guide (available online at www.crownaudio.com),
Crown Tech Support, your system installer or retailer.
We strongly recommend you read all instructions, warnings and cautions contained in this
manual. Also, for your protection, please send in your warranty registration card today, or
register online at www.crownaudio.com. And save your bill of sale—it’s your official proof
of purchase.
page 7
VCA-MC Series Amplifier Accessories
Operation Manual
3 Setup
It is important that you read and understand Section 4 “Operation” and Sec-
tion 5 “Theory of Operation” before completing the setup of the system. Seri-
ous damage may result to the loudspeakers if VCA operation is not well
understood.
The VCA-MC4A and VCA-MC8 can be controlled either by Crown VCAP wall-mount level
controls, by your own potentiometer, or by an external variable-voltage source (0-10 VDC).
3.1 Wiring to the 1-VCAP or 4-VCAP Wall-Mount Control
1. Install a single-gang junction box for the 1-VCAP or a double-gang junction box for the
4-VCAP. Run a cable between the junction box and the power amplifier, allowing some
slack on both ends. No cable is provided. CAT-5 cable will work fine, but Crown recom-
mends using standard twisted-pair shielded microphone cable.
2. See Figure 3.1. In this example, the twisted-pair HOT led is white; the twisted-pair COLD
lead is black. On the VCAP circuit board, pull out and turn over the removable barrier-
strip plug to expose the screws. Then connect the cable leads to the barrier-strip plug
from left to right as follows: COLD lead, HOT lead, Shield. The facing side of the VCAP
circuit board is labeled accordingly.
3. Turn over the barrier-strip plug and insert it into the socket in the VCAP level control.
4. Trap the cable under a wire tie inserted into the holes in the board as shown. Wire-tie
holes are also provided on 4-VCAP panels.
Figure 3.1 Wiring the
VCAP Level Control to the
VCA-MC Module
VCA-MC Series Amplifier Accessories
page 8 Operation Manual
5. Align a supplied barrier plug with the corresponding pins in the VCA-MC4A or
VCA-MC8 module. Attach the cable to the plug as follows:
Connect twisted-pair HOT lead to the VCA channel terminal(s) you want to control.
Connect twisted-pair COLD lead to the +10V terminal.
Connect cable shield to the GND terminal.
The pin labeled GND on the VCA module is connected directly to the internal ground of the
amplifier. NOTE: Do not connect this pin to any ground or extend it for any other
purpose.
In the VCAP wall-mount panel, do not connect the ground pin to the VCAP metal panel or
its junction box.
3.2 Wiring Your Own Potentiometer
You may use your own linear-taper potentiometer to control the VCA-MC module. We rec-
ommend using a 5 k ohm potentiometer; however, values up to 100 k ohms are acceptable.
A potentiometer near 100 k ohms may require an RFI bypass capacitor.
Wire the potentiometer as shown in Figure 3.2. Connect one end-terminal of the pot to the
power-supply ground and VCA ground; connect the other end-terminal to +10 VDC, and
connect the wiper to the VCA control input of your choice (VCA1, VCA2, and so on).
3.3 Wiring to an External Variable DC Voltage Source
The VCA-MC control input is the pin labeled VCA1, VCA2, and so on. It is possible to drive
the control input from an external voltage source such as a Crestron control system. Con-
nect a variable voltage source (0-10 VDC) between the ground pin and control input on the
MC-VCA module. No build-out resistance is required. DO NOT connect to the +10V pin.
The voltage range of the control input is 0 TO 10 VDC. If this range is
exceeded, proper operation is not guaranteed and damage may result to the
VCA card or amplifier.
It is not recommended to draw more than 20mA from the 10V supply. (20mA is approxi-
mately equivalent to having a 5 k ohm potentiometer connected to each channel of an 8-
channel amplifier. Crown-supplied VCAP panels are equipped with 5 k ohm potentiome-
ters). The 10V supply will survive a direct short.
Figure 3.2 Wiring Your Own Potentiometer
page 9
VCA-MC Series Amplifier Accessories
Operation Manual
;;;;;
;;;;;
yyyyy
yyyyy
VCA2
GND
SHIELD
+10V
VCA1
NOTE: When connecting your DC supply to the control pin and ground pin, be sure to avoid
ground loops. The control input filters out most AC voltages but a ground loop can modulate
the gain element of the VCA if the interference is of great enough amplitude.
3.4 Wiring for Multi-Channel Control
Often it is beneficial to control multiple amplifier channels with one control. For example,
some channels of the amplifier may be driving full-range loudspeakers, and other channels
driving subwoofers — all for the same room. In this case, it is convenient to control all of
those channels with the same control. Also, for correct operation when channels are bridged,
control inputs for the bridged channel pairs should always be wired together.
To electrically tie control inputs together, connect the control inputs of the channels together
with a jumper wire, as shown in Figure 3.3. Connect the tied combination to the VCAP wall
panel, or to the external voltage source.
It is recommended (but not mandatory) that the control inputs of bridged channels be electri-
cally tied together even if the VCA option is not used for that channel pair. Wire used to con-
nect two control inputs together should be as short as possible.
Figure 3.3 Example
Showing VCA1 and
VCA2 Tied Together
VCA-MC Series Amplifier Accessories
page 10 Operation Manual
4 Operation
4.1 Operation Using the VCAP Wall-Mount Level Control
1. Turn the amplifier's back panel attenuator fully counterclockwise (off).
2. Unplug the connections to the VCA-MC module if they have been previously installed.
Remember that each connector has two channels on it. Don't unplug the VCA control for
a channel that is in use, because full volume will be sent to that zone since the
VCA attenuation is 0dB when nothing is connected!
3. Turn on your audio source. Set its output level to the maximum value you expect to use it
at. You should not hear any sound yet.
4. Slowly turn the amplifier attenuator clockwise until the system's volume is at the maxi-
mum value you want it to operate at. (Remember to refer to the power rating of the speakers.)
If the sound from your speakers is distorted within the first several detents, consider
decreasing the output level of your audio source.
5. The volume limit of the system is now set. This volume limit is relative to the input level
you just used to set it. If the input level from the audio source increases, so will the output
level of the amplifier. The volume limit is not an absolute limiter.
6. Turn off the amplifier.
7. Plug the VCA control (potentiometer or independent 0-10V DC source) into the VCA-MC
module.
8. Turn the amplifier on.
The VCA level control can now be used to set the system volume at any level between off and
the “volume limit” you just set. See Table 1.
Otros manuales para VCA-MC4A
1
Este manual sirve para los siguientes modelos
3
Tabla de contenidos
Otros manuales de Accesorios para amplificadores de Crown
