PROFESSIONAL POWER AMPLIFIERS
OWNER’S MANUAL
Important Precautions
This symbol is used to
alert the operator to follow important operating
procedures and precautions detailed in documentation.
This symbol is used to
warn operators that
uninsulated “dangerous
voltages” are present
within the equipment
enclosure that may
pose a risk of electric
shock.
1. Save the carton and packing material even if the
equipment has arrived in
good condition. Should
you ever need to ship the
unit, use only the original
factory packing.
2. Read all documentation
before operating your
equipment. Retain all doc-
umentation for future reference.
3. Follow all instructions
printed on unit chassis for
proper operation.
4. Do not spill water or
other liquids into or on
the unit, or operate the unit
while standing in liquid.
5. Make sure power outlets
conform to the power
requirements listed on the
back of the unit.
6. Do not use the unit if the
electrical power cord is
frayed or broken. The
power supply cords should
be routed so that they are
not likely to be walked on
or pinched by items placed
upon or against them, paying particular attention to
cords and plugs, convenience receptacles, and the
point where they exit from
the appliance.
7. Always operate the unit
with the AC ground wire
connected to the electrical
system ground. Precautions
should be taken so that the
means of grounding of a
piece of equipment is not
defeated.
8. Mains voltage must be
correct and the same as
that printed on the rear of
the unit. Damage caused
by connection to improper
AC voltage is not covered
by any warranty.
9. Have gain controls on
amplifiers turned down
during power-up to pre-
vent speaker damage if
there are high signal levels
at the inputs.
10. Power down & disconnect
units from mains voltage
before making connections.
11. Never hold a power
switch in the “ON” position if it won’t stay there
itself!
12. Do not use the unit near
stoves, heat registers,
radiators, or other heat
producing devices.
13. Do not block fan intake or
exhaust ports. Do not
operate equipment on a surface or in an environment
which may impede the normal flow of air around the
unit, such as a bed, rug,
weathersheet, carpet, or
completely enclosed rack.
If the unit is used in an
extremely dusty or smoky
environment, the unit
should be periodically
“blown free” of foreign
matter.
14. Do not remove the cover.
Removing the cover will
expose you to potentially
dangerous voltages. There
are no user serviceable
parts inside.
15. Connecting amplifier out-
puts to oscilliscopes or
other test equipment
while the amplifier is in
bridged mode may damage
both the amplifier and test
equipment!
16. Do not drive the inputs
with a signal level greater
than that required to
drive equipment to full
output.
17. Do not connect the inputs
/ outputs of amplifiers or
consoles to any other voltage source, such as a bat-
tery, mains source, or
power supply, regardless of
whether the amplifier or
console is turned on or off.
18. Do not run the output of
any amplifier channel
back into another channel’s input. Do not parallel- or series-connect an
amplifier output with any
other amplifier output.
Acoustic is not responsible
for damage to loudspeakers
for any reason.
19. Do not ground any red
(“hot”) terminal. Never
connect a “hot” (red) output to ground or to another “hot” (red) output!
20. Non-use periods. The
power cord of equipment
should be unplugged from
the outlet when left unused
for a long period of time.
21. Service Information
Equipment should be serviced by qualified service
personnel when:
A. The power supply
cord or the plug has been
damaged;
B. Objects have fallen,
or liquid has been spilled
into the equipment;
C. The equipment has
been exposed to rain;
D. The equipment does
not appear to operate normally, or exhibits a marked
change in performance;
E. The equipment has
been dropped, or the enclosure damaged.
22. To obtain service, contact
your nearest Service
Center, Distributor, Dealer,
or Crest Audio Customer
Serviece directly at:
Crest Audio Inc.
100 Eisenhower Drive
Paramus NJ 07652
tel 201.909.8700
fax 201.909.8744
http://www.crestaudio.com
Table of Contents
Introduction 2
Unpacking 2
Installation & Mounting 2
Front Panel Controls 2
Back Panel Controls & Connections 3
Operation 4
Protection Features 5
Service Information 5
Operation Mode Drawings 6
Connection Detail Drawings 7
Technical Specifications 8
VsL Series Power Amplifiers Page 1
Models VsL460, VsL900, VsL1500
Introduction
Congratulations on your purchase of a Crest Audio power amplifier. Please
read this manual carefully (and the accompanying “Important Precautions”
pamphlet) as it contains information vital to the safe operation of your amplifier.
Your VsL Series amplifier represents a major step forward in power amplifier
technology and design. It is feature-packed and engineered for value.
All VsL Series models include advanced circuitry capable of providing outstanding reliability and sonic performance, while protection circuitry safeguards your speakers and the amp itself. Built to Crest Audio’s exacting standards from high quality components, VsL Series amplifiers are ideally suited
to the most punishing sound reinforcement applications - fixed or mobile.
Unpacking
Upon unpacking, inspect the amplifier. If you find any damage, notify your
dealer immediately. Only the consignee may institute a claim with the carrier
for damage incurred during shipping. Be sure to save the carton and all packing materials for the carrier’s inspection. It is a good idea to save the carton
and packing material even if the amplifier has arrived in good condition.
Should you ever need to ship the unit back to Crest Audio, one of its offices, or
service centers, use only the original factory packing.
Installation and Mounting
All VsL Series amplifiers are 3-rack space units that can mount in a standard
19-inch rack. Four front panel mounting holes are provided. Rear mounting
ears give additional support, especially important in mobile sound systems.
Because of the cables and connectors on the rear panel, a right-angle or offset
screwdriver or hex key will make it easier to fasten the rear mounting ears to
the rails. Optional rack-mount handles are available from your Crest Audio
authorized dealer.
Front Panel Controls
1. Rack Mounting Ears.
Two front panel mounting holes are provided on each mounting ear.
2. Signal LED.
Each channel has a signal LED. This LED comes on when the input signal
entering the amplifier channel is being amplified.
3. Active LED.
The green Active LED indicates the amplifier is turned on.
4. Protect LED.
If either channel is in Protect mode, this LED will light.
5. Clip LEDs.
Each channel has a clip LED. This LED comes on at clipping point, and indicates that ACL (Active Clip Limiting) is engaged.
6. Fan Intake Grill.
A 110 CFM fan mounted behind the fan intake grill draws cooling air into the
amplifier. Do not block this intake!
7. Input Attenuators.
Two front-panel input attenuators adjust level for their respective amplifier
channels. Minimum attenuation (0dB) equals maximum output. In the bridged
mode, both attenuators are used to control signal level; in addition, both must
be at the same setting
8. AC Power Switch/Circuit Breaker.
VsL Series amplifiers have a combination AC switch/circuit breaker on the
front panel. If the switch shuts off during normal use, push it back to the “ON”
position once. If it will not stay on, the amplifier needs servicing. No fuses are
used.
9. Fan Exhaust Ports.
Heated air exits the amplifier through the fan exhaust ports, located on the
sides of the amplifier chassis. Be sure not to block these ports, especially when
rack-mounting the amplifier.
Front Panel Diagram
1
5.25"
133mm
2 3
Page 2 VsL Series Power Amplifiers
5 6 7 8
4
19" / 483mm
Models VsL460, VsL900, VsL1500
2.25"
57mm
Rear Panel Controls and Connections
11. 5-Way Output Binding Post Connectors.
For connection with bare wire, banana plug or spade lug output connections.
Connection is made either to the Channel A and Channel B terminals (Stereo
Mode), or across the red (“hot”) terminals only of Channels A and B (Bridge
Mode). See the “Operation” Section for more information.
12. Balanced Barrier Strip Input Connectors.
For connection of bare wire cable or spade lug connectors. Note: When connecting unbalanced inputs to the Barrier Strip inputs, make sure to jumper the
negative terminal to the ground terminal. Otherwise, a 6 dB drop in signal
level will result. See drawings 6 & 7 for diagrams detailing Input Barrier Strip
connections.
Rear Panel Diagram
+
+
+
Bridge
CLASS 2 WIRING MAY BE USED
AVIS : RISQUE DE CHOC ÉLECTRIQUE—NE PAS OUVRIR
WARNING TO REDUCE THE RISK OF FIRE OR ELECTRIC SHOCK
DO NOT EXPOSE THIS EQUIPMENT TO RAIN OR MOISTURE.
ATTENTION! POUR ÉVITER LE RISQUE D'INCENDIE OU DE
CHOC ÉLECTRIQUE, NE PLACEZ PAS CET APPAREIL SOUS LA
CAUTION
RISK OF ELECTRIC SHOCK
DO NOT OPEN
PLUIE OU Á L'HUMIDITÉ
5.25"
133mm
220V/240V
~
VsL 460
VsL 900
VsL 1500
Output Power
@4Ω/Ch
50Hz
225W
450W
750W
Output B Output A
13. Balanced TRS (1/4") Connectors.
For connection of balanced TRS Input Plugs. A diagram showing TRS polarity
is shown on drawing 4. Note: Unbalanced "Tip/Sleeve" plugs may be used
with the balanced TRS connectors. The “ring” terminal or negative input will
be connected to ground internally.
14. Mode Selection Switch.
This push-button switch configures the amplifier for either Stereo or Bridged
Mono operation mode. Amplifiers are factory-configured for Stereo Mode. See
the “Operation” Section for more information.
17.125" / 435mm
Designed & manufactured in the USA by:
Crest Audio Inc.
100 Eisenhower Dr.
Paramus New Jersey, 07652 USA
+
B
+ +
+
A
A B
A+B
13
11
12
14
Side Dimensions
VsL460, VsL900 VsL1500
2.25"
57mm
12.0" / 305mm 14.56" / 370mm
9
VsL Series Power Amplifiers Page 3
Models VsL460, VsL900, VsL1500
2.25"
57mm
Operation
Connecting Power / Circuit Size Requirements.
VsL Series amplifier power requirements are rated at “idle”, 1/8th power
(“typical” music conditions), 1/3rd power (“continuous” music conditions),
and maximum rated power. The maximum power current draw rating is limited only by the front panel circuit breaker. Consult the specifications at the end
of this manual for the “typical” current that each amplifier will demand. Mains
voltage must also be correct and the same as that printed on the rear of the
amplifier. Damage caused by connecting the amplifier to improper AC voltage
is not covered by any warranty. Note: Always turn off and disconnect the
amplifier from mains voltage before making audio connections, and as an
extra precaution, have the attenuators turned down during power-up.
Cooling Requirements.
VsL Series amplifiers use a forced-air cooling system to maintain a low, even
operating temperature. Drawn by a two-speed fan mounted behind the front
panel, air enters through the front grill and courses through the cooling fins of
the heat sink, which dissipates power transistor heat, before exiting through the
side panel ports. Make sure that there is enough space around the front of the
amplifier to allow air to enter, and around the sides of the amp to allow the
heated air to exit. If the amp is rack-mounted, do not use doors or covers on
the front of the rack; the exhaust air must flow without resistance. Note:
Whatever type of rack you are using, make sure that the heated air can escape
freely, and that there is no resistance to the intake of cool air through the front
grill.
Mode Selection.
The push-button Mode Select switch (located on the rear panel between input
connections for Channels A and B) configures the amplifier for either Stereo
Mode or Bridged Mono Mode. Amplifiers are factory-configured for Stereo
Mode. To bridge the amplifier, turn it off, and push the mode selection switch
to the “bridge” position. Signal is applied to Channel A’s input only. Both
attenuators are used to control signal level; in addition, both must be set at the
same setting. See the drawings on pages 6 & 7 for essential connection information.
Stereo Mode.
(Drawing 1) In Stereo Mode, both channels operate independently, with their
input attenuators controlling their respective levels. Signal at Channel A’s
input produces output at Channel A’s output, while signal at Channel B’s input
produces output at Channel B’s output. Recommended minimum nominal load
impedance for stereo operation is 2 ohms per channel. Either the 1/4" (TRS)
inputs or the barrier strip inputs may be used. Loudspeakers are connected to
the red and black 5-way output binding posts for each channel.
Bridged Mono Mode.
(Drawing 2) Bridged Mono Mode straps both amplifier channels together to
make a very powerful single channel monaural amplifier. One channel “pushes” and the other “pulls” equally, doubling the power over that of either channel alone. Signal is applied to Channel A’s input only. In the bridged mode,
both attenuators are used to control signal level; in addition, both must be set at
the same setting. Either the 1/4" (TRS) input or the barrier strip input may be
used. Speakers are connected across the red “hot” (+) terminals: connect A’s
terminal to the positive (+) speaker wire, and connect B’s terminal to the negative (-) speaker wire.
Note: Use extreme caution when operating the amplifier in bridged mode.
Never ground either side of the speaker cable when the amplifier is in bridged
mode; both sides are “hot.” If an output patch panel is used, all connections
must be isolated from each other and from the panel. The recommended minimum nominal load impedance in the bridged mode is 4 ohms, which is the
equivalent to driving both channels at 2 ohms. Driving bridged loads of less
than the recommended minimums will activate the IGM circuitry, resulting in
a loss of power, and may also cause a thermal protect condition.
Sending One Signal to Both Channels.
(Drawing 3) To send the same signal to both channels, connect the input signal
to Channel A via the TRS input connector or the Input Barrier Strip. Run
jumpers from the positive and negative connectors of Channel A’s Input
Barrier Strip to those of Channel B’s. Both channels share the input signal, but
will operate independently. Speakers are connected as in Stereo Mode. Note:
Regardless of operating mode, NEVER connect amplifier outputs together!
Connecting Outputs.
Speakers are connected using 5-way Output Binding Post connectors. For
more information, see the sections on Stereo & Bridged Mono mode and
Drawings 1-3.
Connecting Inputs.
Both the barrier strip and 1/4-inch TRS input connectors accept balanced and
unbalanced audio connections. Note: When using three-pole (‘stereo’) TRS
connectors to connect unbalanced signals, make sure that the ring (negative)
connection is made either to the cold (-) output of the source equipment, or to
ground. Unbalanced, two-pole connectors may be used without modification.
In Stereo Mode, one or both channels may be used. In the Bridged Mono
Mode, both outputs are driven from Channel A’s input; Channel B’s input is
unused. Diagrams showing input connections can be found on pages 9 & 10.
Page 4 VsL Series Power Amplifiers
Models VsL460, VsL900, VsL1500
Protection Features.
Every model in the VsL Series incorporates protection features. Derived from
Crest Audio’s extensive experience with the world’s largest sound rental companies, the group of circuits sets new standards in load and amplifier protection.
ACL.
(Automatic Clip Limiting). At the amplifier’s full power, or clipping point,
ACL will be activated. This is is indicated by illumination of the ACL LED,
located at the right end of the meter array. The channel gain will automatically
be reduced, guarding the loudspeakers against the damaging high power, continuous square waves that would otherwise be produced. Situations that may
activate ACL include: uncontrolled feedback, oscillations, or an improper
equipment setting or malfunction upstream from the amplifier. Normal program transients will not trigger ACL; only steady or excessive clipping will.
ACL is virtually transparent in operation and full signal bandwidth is maintained.
IGM Impedance Sensing.
IGM (Instantaneous Gain Modulation) is an innovative circuit that allows the
amplifier to operate safely into loads as low as 2 ohms. When the amplifier
sees a load that overstresses the output stage, the IGM circuit adjusts the channel gain to a safe level. Like ACL, the IGM circuit is inaudible in normal use.
In addition, if extreme low impedance is encountered, the amplifier’s output
relay will open.
AutoRamp Protection.
Auto Ramp operates every time the amplifier is turned on or is reactivated
after a protect condition is corrected. This exclusive Crest Audio feature gradually (-80dB to 0dB in 3.0 seconds) increases gain to the attenuator setting
avoiding unnecessary stress on the loudspeakers.
Thermal Protection.
If the heatsink temperature reaches an abnormally high temperature, the amplifier will protect itself by disconnecting loudspeakers and shutting down until
sufficiently cooled. During this time, the Protect LED’s will light. If the power
transformer gets too hot, its thermal sensing circuit will disconnect both channel outputs. During this time, the Active LED will extinguish, the Protect and
ACL LEDs will stay lit, and the cooling fan will stay running at low speed.
Normal operation will resume automatically once the transformer cools to a
safe level.
Short Circuit.
If an output is shorted (i.e., defective speakers or crossed speaker wires) the
IGM and thermal circuits will automatically protect the amplifier. The IGM
circuit senses the short circuit as an extremely stressful load condition and
attenuates the signal, protecting the channel’s output transistors from overcurrent stress. If the short circuit remains, the load will be disconnected by the
thermal protection circuitry
DC Voltage Protection.
If an amplifier channel detects DC voltage at its output terminals, the output
relay will immediately open to prevent loudspeaker damage. The Protect LEDs
will light.
Subsonic Frequencies.
The VsL Series amplifiers have built-in high pass filtering to provide subsonic
frequency protection for each channel. In addition, a relay will open if excessive subsonic energy appears at the output.
Service Information.
To obtain service, contact your nearest Service Center, Distributor, Dealer, or
the Crest Audio Service Department at:
Crest Audio Inc.
100 Eisenhower Drive
Paramus NJ 07652
tel 201.909.8700
fax 201.909.8744
http://www.crestaudio.com
VsL Series Power Amplifiers Page 5
Models VsL460, VsL900, VsL1500
1. Stereo Mode
Either TRS or Input Barrier
Strips (but not both) may be
used for input connections to
Channels A & B. In this dia-
gram, bare wire has been con-
nected to the Input Barrier
Strip of Channel A, while a
TRS plug is being connected
to Channel B.
2. Bridged Mono Mode
--
+
Output Output
Ch.B
CLASS 2 WIRING MAY BE USED
Designed & manufactured in the USA by:
Crest Audio Inc.
100 Eisenhower Dr.
Paramus New Jersey, 07652 USA
+
B
+
+
Bridge
--
+
+
+
Ch.A
--
+
Output Output
Ch.B
CLASS 2 WIRING MAY BE USED
Bridge
+
+
+
Ch.A
Either TRS or Input
Barrier Strips (but not
both) may be used for
input connection to
Designed & manufactured in the USA by:
Crest Audio Inc.
100 Eisenhower Dr.
Paramus New Jersey, 07652 USA
+
A
A B
A+B
+
+
B
+
+
A
A B
A+B
+
Channel A.
3. Parallel Mode.
+
--
+
Output Output
Ch.B
CLASS 2 WIRING MAY BE USED
Designed & manufactured in the USA by:
Crest Audio Inc.
100 Eisenhower Dr.
Paramus New Jersey, 07652 USA
+
B
+
Bridge
A B
+
--
Input is connected to
Channel A using
either a TRS connec-
tor or the Input
Barrier Strip (but not
+
+
Ch.A
both). Jumper from
Channel A to
Channel B for
ground is not neces-
sary; however, input
ground connection to
Channel A
must be made.
+
A
+
A+B
Page 6 VsL Series Power Amplifiers
Models VsL460, VsL900, VsL1500
4. TRS Polarity
Tip - Positive (+)
Ring - Negative (-)
Sleeve - Ground ( )
+
5. Balanced Input Connections
B
+
+
+
A B
A+B
-
6. Unbalanced Input Connections
+
B
+
A B
A+B
Jumper
+
-
VsL Series Power Amplifiers Page 7
Models VsL460, VsL900, VsL1500
Max RMS Output Voltage
Peak Output Voltage
Frequency Response
Power Bandwidth
SMPTE IMD
Damping Factor
Input Sensitivity
Input Impedance
Hum & Noise
Crosstalk
8Ω Stereo Power †
4Ω Stereo Power †
2Ω Stereo Power †
8Ω Bridged Power †
4Ω Bridged Power †
(each channel)
(each channel)
(+0/-0.3dB, 1W/8Ω)
(Rated power at 4Ω, 1% THD+N)
TourClass Protection
(rated power at 4Ω, 1kHz)
THD+N
(rated power at 8Ω, 60Hz & 7kHz)
(10-400Hz at 8Ω)
Input CMRR
(rated power at 8Ω)
(1 kHz)
Voltage Gain
(balanced/unbalanced)
(“A” weighted, full power at 4Ω)
(“A” weighted, full power at 4Ω)
Input Connectors
Output Connectors
(per channel)
(per channel)
Specifications
VsL460 VsL900 VsL1500
150 Watts
225 Watts
325 Watts
450 Watts
650 Watts
36V
51V
10Hz-20kHz, -3dB @ 165kHz
20Hz-20kHz
ACL, IGM, AutoRamp, short circuit,
DC voltage, turn-on/off transient, current
inrush, sub/ultrasonic input.
<1.0%
<0.05%
>700:1
> - 64dB
.775V
X38.6
>20kΩ/>10kΩ
-105 dB
> - 60 dB
AB
Class
TRS (tip +) & Barrier Strip
5-way binding posts
250 Watts
450 Watts
550 Watts
900 Watts
1100 Watts
52.3V
74V
10Hz-20kHz, -3dB @ 165kHz
20Hz-20kHz
ACL, IGM, AutoRamp, short circuit,
DC voltage, turn-on/off transient, current
inrush, sub/ultrasonic input.
<1.0%
<0.05%
>1000:1
> - 64dB
1.0 V
X40
>20kΩ/>10kΩ
-105 dB
> - 60 dB
AB
TRS (tip +) & Barrier Strip
5-way binding posts
400 Watts
750 Watts
1000 Watts
1500 Watts
2000 Watts
70.7V
100V
10Hz-20kHz, -3dB @ 165kHz
20Hz-20kHz
ACL, IGM, AutoRamp, short circuit,
DC voltage, turn-on/off transient, current
inrush, sub/ultrasonic input.
<1.0%
<0.05%
>1000:1
> - 64dB
1.4V
X38.6
>20kΩ/>10kΩ
-105 dB
> - 60 dB
H
TRS (tip +) & Barrier Strip
5-way binding posts
Power Supply
1/8 Power Curr. Draw
1/3 Power Curr. Draw
Max Curr. Draw
(circuit breaker rating, 120V/4Ω)
Thermal Emissions
Thermal Emissions
LED Indicators
(Height x Width x Depth to rear rack ears)
Filter Storage
(factory configured)
Idle Current Draw
(typical music, 120V/4Ω)
(continuous music, 120V/4Ω)
44,000 µF
100V-240V, 50-60Hz
1.0A
(120V)
3.5A
5.2A
8.0A
(1/8 Power, 4Ω)
(1/3 Power, 4Ω)
Controls
1300 BTU/hr
1530 BTU/hr
Front to Side, one 110 CFM, 2-Speed fan
Cooling
Front Panel: 2 attenuators, magnetic circuit
breaker/power switch.
Rear Panel: mode select switch.
(per channel)
1 Clip, 1 Signal per channel,
Protect, Active
Construction
Dimensions
Gross Weight, Net Weight
†
Power figures are watts per channel, both channels driven, 1kHz, 1% THD. ◊Approximate Values § Limited by Circuit Breaker ‡ Active Clip Limiting.
14 gauge steel
5.25" x 19" x 12" / 133 x 483 x 305mm
38 lbs. / 17.3 kg., 36 lbs. / 16.3 kg.
38,000 µF
100V-240V, 50-60Hz
2.8A
7.2A
10.4A
15.0A
2000 BTU/hr
2900 BTU/hr
Front to Side,one 110 CFM, 2-Speed fan
Front Panel: 2 attenuators, magnetic circuit
breaker/power switch.
Rear Panel: mode select switch.
1 Clip, 1 Signal per channel,
Protect, Active
14 gauge steel
5.25" x 19" x 12" / 133 x 483 x 305mm
46 lbs. / 20.9 kg., 44 lbs. / 20.0 kg.
50,000 µF
100V-240V, 50-60Hz
1.8A
4.3A
8.5A
21.0A
3100 BTU/hr
4400 BTU/hr
Front to Side, one 110 CFM, 2-Speed fan
Front Panel: 2 attenuators, magnetic circuit
breaker/power switch.
Rear Panel: mode select switch.
1 Clip, 1 Signal per channel,
Protect, Active
14 gauge steel
5.25" x 19" x 13.33" / 133 x 483 x 339mm
49 lbs. / 22.2 kg., 46 lbs / 20.9 kg.
Crest Audio reserves the right to make improvements in manufacturing or design which may affect specifications. ©1997 Crest Audio Inc. 8/28/97
Page 8 VsL Series Power Amplifiers
Models VsL460, VsL900, VsL1500
VsL Series Power Amplifiers Page 9
Models VsL460, VsL900, VsL1500
Crest Audio Inc.
100 Eisenhower Dr., Paramus NJ 07652 USA
TEL: 201.909.8700 FAX: 201.909.8744
http://www.crestaudio.com
v. 1.1 10/22/97 © 1997 Crest Audio
Printed in USA
C4400023
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