important precautions
Save the carton and packing materials!
1
Should you ever need to ship the unit,
use only the original factory packing.
For replacement packaging, call Crest Audio’s
Customer Service Depar tment directly.
Read all documentation before
2
operating your equipment. Retain all
documentation for future reference.
Follow all instructions printed on
3
unit chassis for proper operation.
Never hold a power switch in the
4
on-position, if it won’t stay there
by itself!
Do not use the unit if the electrical
5
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.
Always operate the unit with the
6
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
.
Damage caused by connection to
7
improper AC voltage is not covered
by any warranty.Mains voltage must be
correct and the same as that printed on
the rear of the unit.
Do not ground any hot (red) terminal.
8
Never connect a hot
ground or to another hot (red) output!
(red) output to
Do not run the output of any ampli-
¡
fier channel back into another
channel’s input.
Do not parallel- or series-connect
an amplifier output with any
other amplifier output.
Crest Audio is not responsible for damage
to loudspeakers for any reason.
Do not connect the inputs or out-
Ô
puts of amplifiers to any other
voltage source: such as a battery,
mains source, or power supply, regardless of whether the amplifier is turned
on or off.
Connecting amplifier outputs to
£
oscilloscopes or other test equipment while the amplifier is in bridged
mono mode may damage both the
amplifier and test equipment!
Do not spill water or other liquids
¢
into or on the unit, or operate the
unit while standing in liquid.
Do not block fan intake or
ˆ
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.
Service Information
Do not remove the cover!
Removing the cover will expose you to
potentially dangerous voltages.There are
no user serviceable par ts inside.
Equipment should be serviced by
qualified service personnel when:
A. The power supply cord or the plug has
been damaged.
B. The equipment has been exposed to rain.
C. The equipment does not appear to oper-
ate normally, or exhibits a marked change in
performance.
D. The equipment has been dropped, or the
enclosure damaged.
To obtain service:
contact your nearest Crest Audio
Service Center, Distributor, Dealer,
or Crest Audio at 201.909.8700
or visit www.crestaudio.com for addi-
tional information.
email techserve
@crestaudio.com
This symbol is used to alert
the operator to follow important
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.
USA
Power down and disconnect units
9
from mains voltage before making
connections.
Do not drive the inputs with a sig-
0
nal level greater than that
required to enable equipment to
reach full output.
Do not use the unit near stoves,
¶
heat registers, radiators, or other
heat producing devices.
The power cord of equipment
ƒ
should be unplugged from the outlet when left unused for a long period of time.
p. 2
Pro II owner’s manual
how to use this manual
1
conventions
terms
official Crest Audio features and
each indicator or control on the amplifier will appear as: terms
actions
specific actions or selections the user can execute will appear as: actions
tasks
are broken down into steps 1
2
3
warnings
indicators
tips
see
see—refers to other sections of the manual containing
supplementary information on the current topic or a related issue
note
note—supplimentary feature information
Prefered methods.
Helpful hints.
Feature insights.
+
Procedures not to attempt.
Issues or hazards to keep
in mind when operating
the equipment.
a
What to look for on
the equipment display.
Alerts, indicators, or
prompts that may appear.
®
p. 3
introduction
1
welcome
Congratulations on your purchase of a new Pro II Series professional
power amplifier, and thank you for your confidence in Crest Audio products.You are among the growing number of audio professionals who have
made Crest Audio one of the world’s leading suppliers of professional and
commercial/industrial audio systems.
For your safety, please read the Important Precautions section before
installing and operating the amplifier. The Crest Audio Pro II Series is based
on the same advanced circuit topologies that have made Crest’s original
Professional Series amplifiers the choice of touring professionals worldwide. Pro II Series amplifiers are designed for high operating efficiency and
accurate sonic performance across the full audio bandwidth, even under
stressful conditions.
The Pro II Series heralds a major advance in amplifier design from Crest
Audio, providing the extreme reliability and hallmark sonic accuracy for
which Crest products are famous, in a rugged package but at only half the
weight of previous models of similar power.These dramatic weight savings
are made possible by PowerLok, a radical new power-supply technology
that provides significant performance and flexibility advances over conventional designs.PowerLok is Crest Audio's unique implementation of Power
Factor Correction, which allows current to be drawn throughout the
entire cycle of the
AC line-frequency, providing maximum output power,
while drawing significantly smaller peak currents from the
AC line.
Compared with an amplifier using a conventional power-supply, PowerLok
requires less peak power to produce identical output power, and because
PowerLok's current peaks are smaller, a Pro II amplifier can be serviced by
a lower-rated breaker than a conventional amplifier of similar wattage. See
separate literature for full details on the benefits of PowerLok technology.
In order to maintain strict quality assurance standards, all Crest Audio
power amplifiers are built in our state-of-the-art
USA manufacturing facili-
ty. Internal components are the finest available and key sub-assemblies are
pre-tested before final assembly. Each amplifier is “burned in” and thoroughly tested
(using precision audio test equipment) before shipping. In
addition, all Pro II Series amplifiers incorporate Crest’s exclusive TourClass
protection features to safeguard both internal circuitry and connected
loudspeakers.
This proven combination of advanced design, quality construction, and
comprehensive circuit protection is your guarantee of fail-safe reliability.
You can depend on consistent, stable performance even when your Pro II
Series amplifier is subjected to punishing extremes in the most demanding
fixed or mobile sound reinforcement applications.
Pro II owner’s manual
p. 6
installation
2
unpacking
Please inspect the amplifier carefully immediately after unpacking.If you find
any damage, notify your supplier/dealer immediately. Only the shipper may
file a damage claim with the carrier for damage incurred during shipping. Be
sure to save the carton and all packing materials for the carrier’s inspection.
If the packing materials are in good condition, please save them.
If you ever need to ship the unit back to Crest Audio or an authorized service center, you should use only the original factory packing.
For replacement packaging, call Crest Audio’s
Customer Service
Department directly.
see—service and support
+
Pro II owner’s manual
p. 8
installation
2
To ensure optimum
cooling of the amplifier,
periodically clean its fan
filters. These are removable
without tools.
Make certain that there is
enough space around the
front of the amplifier
to allow the heated air to
escape. If the amplifier is
rack-mounted, do not use
doors or covers on the front
of the rack; the exhaust air
must not be impeded
In racks with closed backs:
for every four amplifiers,
allow at least one standardrack-space opening in the
front of the rack.
a
cooling and ventilation
Pro II Series amplifiers use a twin-tunnel forced-air cooling system to maintain a low, even operating temperature.
Drawn in by dual 105
CFM (cubic feet-per-minute) DC fans on the rear panel,
air flows through the cooling fins of the channel heat-sinks,dissipating power
transistor heat
—then exhausts through the front panel slots.
Heat sink temperature-sensing circuits control the “intelligent” variablespeed fans. Fan speed increases only as required by heat-sink temperatures
—
keeping fan noise to a minimum.
Under extreme thermal load, the fans will force a very large volume of air
through the heat sinks. If either heat-sink surpasses the maximum allowed
temperature, the sensing circuit will open the output relay, disconnecting the
load from that channel.
If the power supply overheats, another sensing circuit opens both channel
output relays, until it has cooled to a safe temperature.
p. 9
installation
2
powering
Unless otherwise specified when ordered, Pro II amplifiers shipped to customers are configured as follows:
North America 90–255
VAC
@
50–60Hz
Europe 180–255 VA C @50–60Hz
Asia 180 –255 VAC @50–60Hz
Australasia 180–255 VA C @50–60Hz
South America 90–255 VAC @50–60Hz
Japan 90–255 VA C @50–60Hz
maintenance
A Pro II Series amplifier requires no routine maintenance other than the
occasional cleaning or replacement of the fan intake filters on the rear of the
amplifier.
(This operation does not require any tools.) Filters must be kept
clear and clean to ensure proper ventilation through the unit.
If the amplifier is used in an extremely dusty or smoky environment, the filter should be cleaned or changed frequently and the unit should be periodically “blown free”
(using compressed air) of any foreign matter that may have
penetrated the filter.
Users will not need to make any internal adjustments to the amplifier during its lifetime. There are no user-serviceable parts or adjustments that
require opening the power amplifier.
Always turn off and disconnect the amplifier from
mains voltage before making audio connections.
As an extra precaution, have
the attenuators turned down
during power-up.
a
Cover removal exposes
the risk of shock, so refer
all servicing to qualified
service technicians authorized by Crest Audio.
a