Page 1
PROFESSIONAL POWER AMPLIFIERS
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0dB
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Signal
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OWNER’ S MANUAL
Page 2
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 connec-
tion to improper AC voltage is not covered by any warranty.
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 outputs to
oscilloscopes 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 battery,
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 amplifi-
er 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.
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
Crest Audio Service Center,
Distributor, Dealer, Crest Audio at
201.909.8700 (USA).
9. Have gain controls on amplifiers
turned down during power-up to prevent speaker damage if there are high
signal levels at the inputs.
19. Do not ground any red (“hot”) ter-
minal. Never connect a “hot” (red)
output to ground or to another “hot”
(red) output!
Page 3
Power Amplifier Owner’s Manual
Table of Contents
Introduction
Unpacking
Installation and Mounting
Front Panel
Back Panel
Internal Configuration and Control
Operation
Connecting Power / Circuit Size Requirements
Cooling Requirements
Connecting Inputs
Connecting Outputs
Mode Selection
Stereo /Parallel/Bridged Mono Connections
TourClass®Protection Features
User Precautions
Speaker Protection
Recommended Speaker Cabling
Maintenance
User Responsibility
Service and Repair
5
5
5
6
7
8
9
9
9
10
10
11
12
13
14
14
14
15
15
15
Appendix A Specifications
Appendix B HD Block Diagram
Appendix C Wire Gauge Charts
Appendix D Rear Panel Symbols - Legend
Appendix E HD18 Special Functions
Appendix F Warranty Information
Crest Audio HD Series Power Amplifiers Page 3
Models HD2, HD4, HD6, HD9, HD12, HD18
Page 4
HD12, 18 Front View
Front
height
5.25"
133mm
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Active
Ch B
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Clip
Signal
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0dB
Front width 19" / 483mm
HD2-9 Front View
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Clip
Signal
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0dB
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0dB
Rear
height
3.5"
89mm
Protect
Active
Protect
Active
Front width 19" / 483mm
Ch A
Ch B
Rear/Side Views HD2-9 (Top), HD12, HD18 (Bottom)
A
A
+
+
A
B
+
B
17.9"/437mm (19"/483mm to rack ears)
A
•
•
AB
A
+
A
B
••
A
B
B
A
B
2+
1
3-
3.5"
89mm
CA2
CA4
CA6
CA9
1.375"
35mm
18"/457mm
2+
1
3-
A
A
+
+
A
B
+
B
A
•
•
AB
A
+
A
B
••
A
B
B
A
B
5.25"
133mm
CA12
CA18
See appendix E for detailed drawing and information regarding model HD18
Page 4 Crest Audio HD Series Power Amplifiers
Models HD2, HD4, HD6, HD9, HD12, HD18
Page 5
Introduction
Congratulations on your purchase of a new HD 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 HD Series is based on the same advanced circuit topologies that have made Crest ampli-
fiers the choice of touring professionals worldwide. HD Series amplifiers are designed for high operating
efficiency and accurate sonic performance across the full audio bandwidth, even under stressful conditions.
In order to maintain strict quality assurance standards, all HD Series amplifiers are built in Crest’s state-ofthe-art USA manufacturing facility. Internal components are the finest available, and key sub-assemblies are
pre-tested before final assembly. Finally, each amplifier is “burned in” and thoroughly tested (using precision audio test equipment) before shipping. In addition, all HD 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
HD Series amplifier is subjected to punishing extremes in the most demanding fixed or mobile sound reinforcement applications.
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 your 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.
Installation and Mounting
Four HD Series amplifiers are 2-rack-space units: models 2, 4, 6, and 9. The HD Series models 12 and 18
are 3-rack-spaces high. All mount in standard 19-inch racks. Four front-panel mounting holes are provided
on each amplifier. Rear mounting ears give additional support, and use of rear supports is highly recommended in all mobile and touring sound systems. Optional rack-mount handles are available. Dimension
drawings are included on page 4.
Crest Audio HD Series Power Amplifiers Page 5
Models HD2, HD4, HD6, HD9, HD12, HD18
Page 6
Front Panel
1
2 3
4
5
6
Protect
Active
Ch A
Protect
Active
Ch B
7 8 9
Clip
Signal
Clip
Signal
-6
-10
-3
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-80
0dB
-6
-10
-3
-15
-30
-80
0dB
-1
-1
1. Rack Mounting Ears.
Two front panel mounting holes are provided on each mounting ear.
2. Optional Rack Handles.
Available from your authorized supplier.
3. Fan Outlet Grills.
Never try to hold the
circuit breaker/power
switch in the “ON”
position if it won’t stay
there itself!
Granit Line amplifiers are cooled by two, rear-mounted fans. Cool air flows over the heat sinks and exhausts
through the front grills. Make sure these outlets remain clear to allow unrestricted air flow.
4. AC Power Switch/Circuit Breaker.
Granit Line amplifiers have a front-panel combination AC switch and circuit breaker. (No fuses are used.) 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.
5. Active LED.
Indicates that AC power is connected and the amplifier is turned on.
6. Protect LED.
Indicates that the channel is in Protect mode (speakers disconnected by output relay).
7. Clip LED.
Illuminates at the clipping threshold. Continuous illumination also indicates that
ACL (Active Clip Limiting) protection circuitry is engaged.
8. Signal LED.
Illuminates to indicate that a signal (above a minimum threshold) is present at the amplifier input, and that
the signal is being amplified.
9. Input Attenuators.
Two input attenuators adjust level for their respective amplifier channels. In Bridged Mono Mode, both
attenuators are used to control signal level and must be adjusted to the same setting.
Page 6 Crest Audio HD Series Power Amplifiers
Models HD2, HD4, HD6, HD9, HD12, HD18
Page 7
Never connect a “hot” (red) output to
ground or to another “hot” (red) output!
Rear Panel See Appendix E for information specific to model HD18.
CAUTION
RISK OF ELECTRIC SHOCK
DO NOT OPEN
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 PLUIE OU Á
L'HUMIDITÉ
A
A
B
A
AB
A
B
B
A
11 12
A
+
+
A
B
+
B
10
A
•
•
+
••
B
13
14
Designed & manufactured in the USA by:
Crest Audio Inc.
100 Eisenhower Dr.
Paramus, New Jersey 07652 USA
2+
1
3-
15
10. Output Connectors
Your amplifier is supplied with 5-way Output Binding Posts. Connection to the binding posts can be made
with bare wire, banana plugs, or spade lug terminations. Make connections to both the Channel A and
Channel B terminals for Stereo or Parallel Mode, or a single connection across the red (“hot”) terminals
only of Channels A and B for Bridged Mono Mode. See Appendix D and the section on Mode Selection for
more information. NOTE: on the HD18, two pairs of 5-way binding posts are provided for each channel, so
that paralleling of speakers is possible.
11. Mode Selection Switch.
This recessed, three-position switch configures the amplifier for Stereo, Parallel or Bridged Mono Mode
operation. Amplifiers are factory-configured for Stereo Mode. See Appendix D and the section on Mode
Selection for more information.
12. Signal Ground Lift Switch.
The recessed signal ground lift switch is factory-set to the ‘ground’ (bottom) position, which electrically
connects the signal ground to the chassis/AC ground. The top position lifts the amplifier’s signal ground. In
a properly designed system (for safety purposes and to minimize noise), the amplifier should be connected
to ground through the AC line cord. Also, whenever possible, the signal source equipment should share the
same AC ground as the amplifier. In some cases this may not be possible, and a ground loop results. If this
happens, the first step is to move the ground lift switch to the top (‘lift’) position. In this position, the signal
ground is lifted and completely isolated from the chassis/AC ground. Do not change the switch to the ‘lift’
position if the amplifier and the signal source equipment are on the same AC ground. Should the ground
loop problem persist after the ground lift switch has been set to the ‘lift’ position, then the shield on balanced input lines should be grounded at one end only (usually the signal source).
Crest Audio HD Series Power Amplifiers Page 7
Models HD2, HD4, HD6, HD9, HD12, HD18
Page 8
13-14. Balanced 1/4" (TRS) & XLR Input Connectors.
These connectors accept input signals on balanced TRS and XLR input plugs.
See the figure at the left for information on polarity. Connectors for each channel are in parallel; the unused connectors may be used for “loop through” con-
Tip - Positive (+)
Ring - Negative (-)
Sleeve - Ground ( )
+
nection to other amplifiers.
Note: Unbalanced “Tip/Sleeve” plugs may be used with the balanced TRS
“Tip/Ring/Sleeve” connectors. The “ring” terminal or negative input will be
connected to ground internally. When using three-pole (‘stereo’) TRS connectors, make sure that the ring connection is made either to the cold (–) output of
1 - Ground ( )
the source equipment, or to ground. Incorrect connections may cause a 6dB loss
in level.
3 - Negative (-)
2 - Positive (+)
15. Fan Inlet Ports & Filters.
Cooling air enters the amplifier through the fan inlet ports located on the rear of the amplifier chassis. Be
sure not to block these ports when installing the amplifier or other associated equipment. Air must flow
unimpeded through these ports. Removable fan filters are provided to minimize entry of dust and dirt.
Internal Configuration and Control
Input XLR Polarity
HD Series amplifiers are supplied standard with the XLR configured as “Pin 2 hot” (+). On models HD2,
HD4, HD6, HD9 and HD12, an internal jumper makes it possible to alter the amplifier to “Pin 3 hot” (+).
NOTE: This jumper is NOT user configurable. Please consult your supplier or lohdl Crest Audio service
center if you wish to have the input XLR polarity changed
On the HD18, an external XLR polarity switch is featured. (See Appendix E).
Input Sensitivity
The HD Series amplifiers have a standard input sensitivity of .775 Volts for rated power at 8 Ohms. Models
HD2, HD4, HD6, HD9 and HD12 are fitted with an internal jumper which allows optional gains of X20 or
X40. Model HD18 features an external voltage gain/input sensitivity switch (See Appendix E). Standard
and optional voltage gains/input sensitivities are detailed below.
HD2 HD4 HD6 HD9 HD12 HD18
Gain Sens Gain Sens Gain Sens Gain Sens Gain Sens Gain Sens
Std. X45 .775V X61 .775V X68 .775V X86.5 .775V X97.5 .775V X115 .775V
Opt. 1 X40 .866V X40 1.12V X40 1.32V X40 1.66V X40 1.87V X40 2.24V
Opt. 2 X20 1.73V X20 2.24V X20 2.65V X20 3.32V X20 3.74V X20 4.47V
NOTE: This jumper is NOT user configurable. Please consult your supplier or local Crest Audio service
center if you wish to have the voltage gain / input sensitivity changed.
Page 8 Crest Audio HD Series Power Amplifiers
Models HD2, HD4, HD6, HD9, HD12, HD18
Page 9
Operation
Connecting Power / Circuit Size Requirements.
HD Series amplifier power requirements are rated at:
a) “idle”
b) 1/8th power (“typical” music conditions)
c) 1/3rd power (“continuous” music conditions)
d.) maximum rated power.
The maximum power current draw rating is limited only by the front panel circuit breaker. Consult the specifications in the Appendices section for figures on the current that each amplifier will demand.
Make sure the mains voltage is correct and is 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. Unless otherwise specified when ordered, Crest amplifiers shipped to customers are configured as follows:
North America - 120VAC / 60Hz
Europe - 230VAC / 50Hz
Asia - 220VAC / 50Hz
Australasia - 240VAC / 50Hz
South America - 120VAC / 60Hz or 220VAC / 50Hz
Japan - 100VAC / 50Hz
Note: Always turn off and disconnect the amplifier from mains voltage before making audio connections.
Also, as an extra precaution, have the attenuators turned down during power-up.
Cooling System and Requirements.
HD Series amplifiers use a twin-tunnel forced-air cooling system to maintain a low, even operating temperature. Drawn in by dual 45 cubic feet-per-minute (CFM) 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.
The “intelligent” variable-speed DC fans are controlled by heat sink temperature sensing circuits. When the
amplifier is turned on, the fans briefly “rev up,” then slow to an idle; this indicates that the temperature
sensing circuits are operating normally. The 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 transformer overheats,
another sensing circuit opens both channel output relays until the transformer cools to a safe temperature.
IMPORTANT: To ensure optimum cooling, periodically clean the amplifier fan filters (removable without
tools). Also make certain that there is enough space around the front of the amplifier to allow the cooling
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 flow out without resistance. If the amplifiers are to be housed in racks with closed backs,
allow at least one (1) standard rack space of opening in the front of the rack for every four amplifiers.
Crest Audio HD Series Power Amplifiers Page 9
Models HD2, HD4, HD6, HD9, HD12, HD18
Page 10
Connecting Inputs.
Use either the XLR or 1/4-inch input connectors on the rear to supply audio signals to your Crest Audio HD
Series amplifier. Both connectors accept balanced and unbalanced audio connections. (The HD Series
amplifiers are configured standard with “Pin 2 hot” on XLR inputs. Please note that some other Crest Audio
amplifiers are configured with “Pin 3 hot”). The unused connector can be used to jumper the audio input to
another amplifier input. For more information, see the sections on Balanced 1/4" (TRS) & XLR Input
Connectors, Input XLR Polarity, and Input Sensitivity
Connecting Outputs.
Speakers are connected using 5-way Output Binding Posts. Please note that on the HD18, two pairs of 5way binding posts are provided for each channel, so that paralleling of speakers is possible.
For more information, see the sections on Output Connectors and Mode Operation and the figures on page
12.
Page 10 Crest Audio HD Series Power Amplifiers
Models HD2, HD4, HD6, HD9, HD12, HD18
Page 11
Mode Selection.
The three-position, recessed Mode Select switch (located on the rear panel) configures the amplifier for
either Stereo, Parallel or Bridged Mono Mode. Amplifiers are factory-configured for Stereo Mode.
Stereo Mode.
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 XLR inputs may be used.
Parallel Mode.
When set to Parallel Mode, a signal applied to Channel A’s input will be amplified and appear at outputs for
both Channels A & B. Either the 1/4" (TRS) input or the XLR input on Channel A may be used.
Bridged Mono Mode.
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 the Channel A input only. Both attenuators are used to control signal level; in addition, both must be adjusted to the same setting. Either the 1/4" (TRS) or XLR input may be
used.
NOTE: The channel B input connectors (XLR and/'or TRS) may be used to “Loop Thru” the channel A signal when in parallel or bridged mono mode.
Use extreme caution when operating the amplifier in Bridged Mono Mode. Never ground either side of the
speaker cable when the amplifier is in Bridged Mono 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 Mono Mode is 4 ohms, which is the equivalent to driving both
channels separately 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 lead to a thermal protect condition.
See figures on page 12 showing output connection information.
Connecting amplifier outputs to oscilloscopes or other test equipment while the
amplifier is in bridged mode may damage both the amplifier and test equipment!
Crest Audio HD Series Power Amplifiers Page 11
Models HD2, HD4, HD6, HD9, HD12, HD18
Page 12
Stereo Mode Connections
(5-Way Output Binding Posts)
+
+
A
or
A
A
A
+
+
A
B
+
B
A
•
•
AB
A
+
A
B
••
A
B
B
A
B
B
A
2+
1
3-
B
Parallel Mode Connections
(5-Way Output Binding Posts)
Bridged Mono Mode Connections
(5-Way Output Binding Posts)
B
A
+
+
+
+
+
A
Bridged/Mono
+
+
+
+
or
or
A
A
A
A
B
B
A
•
•
AB
A
+
A
B
••
B
A
B
A
B
1
A
2+
3-
or
A
A
A
A
A
B
B
A
•
•
AB
A
+
A
B
••
A
B
B
A
B
A
643-106
2+
1
3-
Page 12 Crest Audio HD Series Power Amplifiers
Models HD2, HD4, HD6, HD9, HD12, HD18
Page 13
TourClass®Protection Features
Every model in the HD Series incorporates TourClass protection features. Derived from Crest Audio’s
extensive experience with the world’s largest sound rental companies, the TourClass group of circuits sets
the industry standard for assured protection of internal amplifier circuits and all connected loads.
ACL. (Active Clip Limiting).
At the amplifier’s full power limit, or clipping point, ACL will be activated. This is indicated by illumination of the Clip LED. The channel gain is automatically reduced, protecting the loudspeakers from potential
damage from the high power, continuous square waves that would otherwise be produced. ACL may be
activated by uncontrolled feedback, oscillations, improper equipment gain settings, or an equipment malfunction upstream from the amplifier. Only steady or excessive clipping (not normal program transients)
will trigger ACL. The circuit 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 and sustained low impedance is encountered, the amplifier’s output relay will open.
AutoRamp Protection.
AutoRamp operates every time the amplifier is turned on or is reactivated after a protect condition is corrected. This exclusive Crest Audio feature gradually increases gain to the attenuator setting avoiding unnecessary stress on the loudspeakers.
Thermal Protection.
Abnormally high heat sink temperatures will engage the Protect circuit for the overheating channel only.
(An output relay disconnects the loudspeakers until nominal temperature range is restored.) During this
time, the Protect LED 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 Clip LEDs
will stay lit, and the cooling fan will continue running at low speed. Normal operation resumes 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 over-current stress. If
the short circuit remains, the load will be disconnected by the thermal protection circuitry (output relay
opens).
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.
Built-in high pass filtering provides subsonic frequency protection for each channel. In addition, a relay will
open if excessive subsonic energy appears at the output.
Crest Audio HD Series Power Amplifiers Page 13
Models HD2, HD4, HD6, HD9, HD12, HD18
Page 14
User Precautions
Speaker Protection
All loudspeakers have electrical, thermal, and physical limits which must be observed to prevent damage or
failure. Cone or compression drivers can be damaged (sometimes to the point of failure) from excessive
power, low frequencies applied to high frequency drivers, severely clipped waveforms, and DC voltage. All
HD Series amplifiers automatically protect speakers from DC voltages and subsonic signals. For more
information, see the section on Protection Features.
Mid- and high-frequency transducers–compression drivers in particular–are highly susceptible to damage
from overpowering, clipped waveforms, or frequencies below their rated passband. When using an electronic crossover, make absolutely certain that the low and mid bands are connected to the correct amplifiers and
drivers—and not accidentally connected to those for a higher or lower frequency band.
The amplifier’s clipping point is its maximum peak output power. At maximum peak output power, Crest
Audio HD Series amplifiers will deliver more power than many speakers can safely handle. Be sure the
peak power capability of the amplifier is not excessive for your speaker system. To ensure that the speakers
never receive excessive power, and to prevent amplifier clipping, use a properly adjusted external limiter (or
a compressor with a ratio of 10:1 or higher) to control power output. Use one compressor/limiter for each
frequency band in systems with active electronic crossovers.
The ACL clip limiting circuit will automatically limit the duration of squared-off, continuous waveforms
applied to the speakers. The amplifier will, however, allow normal musical transient bursts to pass. Of
course, when the amplifier does clip, it is operating at its maximum output power. Note that some speaker
systems are packaged with proprietary “processors” that have power limiting circuits and therefore should
not require additional limiting.
Do not drive any low-frequency speaker enclosure with frequencies lower than its own tuned frequency; the
reduced acoustical damping could cause a ported speaker to “bottom out” even at moderate power. Consult
the speaker system specifications to determine its frequency limits, and employ a roll-off filter if necessary.
Recommended Speaker Cabling
The wire gauge charts will assist you in determining the optimum copper wire gauge for your speaker
cables. Remember that the speaker cable resistance robs amplifier power in two ways: through power lost
2
directly to resistance (often referred to as I
R loss), and through increased total load resistance, which
decreases the amount of power available from the amplifier. The charts (Appencix C) give cable length figures in feet/AWG wire gauges and in metric values.
Page 14 Crest Audio HD Series Power Amplifiers
Models HD2, HD4, HD6, HD9, HD12, HD18
Page 15
Maintenance
A HD Series amplifier requires no routine maintenance other than occasional cleaning or replacement of the
fan intake filters on the rear of the amplifier. These 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 penetrated through the filter.
Users will not need to make any internal adjustments to the amplifier during its lifetime. There are no userserviceable parts or adjustments that require opening the power amplifier. Cover removal exposes the risk of
shock, so refer all servicing to qualified service technicians authorized by Crest Audio.
User Responsibility
Your HD Series amplifier is very powerful and can be potentially dangerous to loudspeakers and operators
alike. It is your responsibility to read the section titled “Important Precautions” and make sure that the
amplifier is installed, wired, and operated properly as instructed in this manual. Many loudspeakers can be
easily damaged or destroyed by overpowering, especially with the high power available from a bridged
amplifier. Read the section on Speaker Protection and always be aware of the speaker’s continuous and peak
power capabilities. Crest Audio is not responsible for damage to loudspeakers for any reason.
Service and Repair
In the unlikely event that your amplifier develops a problem, it must be returned to an authorized distributor,
service center or shipped directly to our factory. To obtain service, contact your nearest Crest Audio Service
Center, Distributor, Dealer, or any of the worldwide Crest Audio offices. For contact information, reach
Crest Audio Inc. Customer Service directly at: TEL. 201.909.8700 (USA) FAX. 201.909.8744 (USA).
Because of the complexity of the design and the risk of electrical shock, all repairs should be attempted only
by qualified technical personnel. If the unit needs to be shipped back to the factory, it must be sent in its
original carton. If improperly packed, your amplifier may be damaged.
For those with Internet access, please visit the Crest Audio website at: http://www.crestaudio.com
Crest Audio HD Series Power Amplifiers Page 15
Models HD2, HD4, HD6, HD9, HD12, HD18
Page 16
Page 17
Appendices
Page 18
1kHz, 0.01% THD+N
8Ω Stereo Power
4Ω Stereo Power
2Ω Stereo Power
8Ω Bridged Mono Power
4Ω Bridged Mono Power
20Hz-20kHz, 0.1% THD+N
8Ω Stereo Power
4Ω Stereo Power
2Ω Stereo Power
8Ω Bridged Mono Power
4Ω Bridged Mono Power
Appendix A - Amplifier Specifications
HD2 HD4 HD6 HD9 HD18HD12
160W
250W
N/A
500W
N/A
150W
200W
N/A
450W
N/A
250W
435W
500W
830W
1000W
245W
400W
450W
800W
900W
400W
600W
750W
1200W
1500W
350W
500W
600W
1000W
1200W
600W
900W
1000W
1800W
2000W
550W
800W
900W
1600W
1800W
700W
1200W
1400W
2400W
2800W
650W
1100W
1100W
2200W
2200W
1000W (.03% THD+N)
1800W (.03% THD+N)
2500W (.03% THD+N)
3600W (.03% THD+N)
5000W (.03% THD+N)
950W
1700W
2400W
3400W
4800W
Max RMS Output Voltage (each channel)
Max Peak Output Voltage
Frequency Response (+0 / -0.3dB, 1W/8Ω)
Power Bandwidth (rated power at 4Ω, 1%THD+N)
TourClass Protection
(rated power, 4Ω/1kHz)
SMPTE IMD
Standard Input Sensitivity
Standard Voltage Gain
Hum and Noise
THD+N
(rated power, 8Ω, 60 Hz & 7kHz)
Damping Factor
Input Impedance
("A" weighted, full power at 4Ω)
Crosstalk
("A" weighted, full power at 4Ω)
(10-400Hz at 8Ω)
Input CMRR
(balanced/unbalanced)
(1kHz)
(rated power at 8Ω) ‡
(rated power @ 8Ω) ‡
Class
Input Connectors
Output Connectors
(per channel)
(per channel)
Filter Storage
Power Supply
1/8 Power Curr. Draw
1/3 Power Curr. Draw
Max Curr. Draw
Thermal Emissions
Thermal Emissions
(factory configured)
Idle Current Draw
(typical music cond., 120V/4Ω)
(cont. music cond., 120V/4Ω)
(continuous music cond., 120V/4Ω)
(120V)
(1/8 Power, 4Ω)
(1/3 Power, 4Ω)
Cooling
Controls
LED Indicators (per channel)
Construction
(Height x Width x Depth to rear rack ears)
Dimensions
Gross Weight
Net Weight
Warranty
Crest Audio reserves the right to make changes or improvements in manufacturing or design which may affect specification. ©1997 Crest Audio Inc. 5/21/97
Factory Standard X45 .775V X61 .775V X68 .775V X86.5 .775V X97.5 .775V X115 .775V
Option 1 X40 .866V X40 1.12V X40 1.32V X40 1.66V X40 1.87V X40 2.24V
Option 2 X20 1.73V X20 2.24V X20 2.65V X20 3.32V X20 3.74V X20 4.47V
44V
62V
20Hz-20kHz,
20Hz-20kHz,
-3dB@135kHz
-.9dB/+.15dB
58V
82V
20Hz-20kHz,
20Hz-20kHz,
-3dB@135kHz
-.9dB/+.5dB
73V
103V
20Hz-20kHz,
20Hz-20kHz,
-3dB@135kHz
-1.1dB/+0dB
82V
116V
20Hz-20kHz,
20Hz-20kHz,
-3dB@135kHz
-.84dB/+0dB
90V
126V
20Hz-20kHz,
20Hz-20kHz,
-3dB@135kHz
-.23dB/+.85dB
99V
140V
20Hz-20kHz, 20Hz-20kHz, -
3dB@150kHz
.2dB/+.2dB
ACL, IGM, AutoRamp, short circuit, DC voltage, turn-on/off transient, current inrush, sub/ultrasonic input
<0.01%
<0.01%
368:1
> - 60 dB
0.775V
X45
>20kΩ/>10kΩ
-105dB
> - 60dB
AB
<0.01%
<0.01%
550:1
> - 60 dB
0.775V
X61
>20kΩ/>10kΩ
-105dB
> - 60dB
AB
<0.01%
<0.01%
400:1
> - 60 dB
0.775V
X68
>20kΩ/>10kΩ
-105dB
> - 60dB
H
<0.01%
<0.01%
700:1
> - 60 dB
0.775V
X86.5
>20kΩ/>10kΩ
-105dB
> - 60dB
H
<0.01%
<0.01%
800:1
> - 60 dB
0.775V
X97.5
>20kΩ/>10kΩ
-105dB
> - 60dB
H
<0.03%
<0.01%
800:1
> - 70dB
0.775V
X115
>20kΩ/>10kΩ
-115dB
> - 80dB
H
Female XLR (pin 2+, configurable for pin 3+), TRS (tip+)
5-way binding posts (2 pair on HD18)
20,000 µF
100V-240V, 50-60Hz
1.2A
3.25A
5.5A
9.0A
1119 BTU/hr
1607 BTU/hr
27,200 µF
100V-240V, 50-60Hz
1.4A
6.8A
10.0A
15.0A
2030 BTU/hr
2726 BTU/hr
68,000 µF
100V-240V, 50-60Hz
1.6A
6.0A
13.0A
18.0A
2630 BTU/hr
3713 BTU/hr
80,000 µF
100V-240V, 50-60Hz
2.0A
8.6A
16.0A
21.0A
3250 BTU/hr
4341 BTU/hr
140,000 µF
100V-240V, 50-60Hz
2.8A
10.5A
23.0A
30.0A
4750 BTU/hr
6300 BTU/hr
144,000 µF
100V-240V, 50-60Hz
3.0A
12.0A
25.0A
36.0A
7125 BTU/hr
9450 BTU/hr
Two rear panel variable speed DC fans, filters detatchable without tools
Front panel: 2 attenuators, magnetic circuit breaker/power switch; Rear panel: signal ground lift & mode switches, (HD18: XLR polarity & input sens./voltage gain switches)
Clip/Limit, Signal, Temp/DC, Active
Steel chassis, 16 gauge. Double thickness in rack ear areas.
3.5" x 19" x 18"
89 x 483 x 457mm
38 lbs. (17.25 kg)
33 lbs. (14.98 kg)
3 years
3.5" x 19" x 18"
89 x 483 x 457mm
46 lbs. (20.88 kg)
41 lbs. (18.61 kg)
3 years
3.5" x 19" x 18"
89 x 483 x 457mm
49 lbs. (22.24 kg)
44 lbs. (19.97 kg)
3 years
3.5" x 19" x 18"
89 x 483 x 457mm
52lbs. (23.60 kg)
47 lbs. (21.33 kg)
3 years
5.25" x 19" x 18"
133 x 483 x 457mm
72 lbs. (32.68 kg)
67 lbs. (30.42 kg)
3 years
5.25" x 19" x 18"
133 x 483 x 457mm
82 lbs. (37.23 kg.)
77 lbs. (34.96 kg.)
3 years
† For full power at 4 Ohms. ‡ See table below for dealer-configurable options.
HD2 HD4 HD6 HD9 HD12 HD18
Gain
Sens Gain Sens Gain Sens Gain Sens Gain Sens Gain Sens
Appendix A Crest Audio HD Series Power Amplifiers
Models HD2, HD4, HD6, HD9, HD12, HD18
Page 19
Appendix B - HD Block Diagram
R
T
+
2
3
NON-INVERTED
2 / 3
CHANNEL A
PREAMP
†
ATTENUATOR
OUTPUT STAGE
- INVERTED
1
2
3
1
PIN 2 / 3 +
JUMPER
(REAR PANEL SWITCH
R
T
PIN 2 / 3 +
JUMPER
(REAR PANEL SWITCH
ON CA18)
2 / 3
B
NON-INVERTED
+
B
INVERTED
-
A
-
BRIDGED
-
PARALLEL
-
STEREO
SWITCH
A
+
+
-
†
PREAMP INCORPORATES INPUT
SENSITIVITY/VOLTAGE GAIN JUMPER
(REAR PANEL SWITCH ON CA18)
†
PREAMP
ATTENUATOR
CHANNEL B
AMP FRONT END
OUTPUT STAGE
AMP FRONT END
OUTPUT RELAY
OUTPUT RELAY
Crest Audio HD Series Power Amplifiers Appendix B
Models HD2, HD4, HD6, HD9, HD12, HD18
Page 20
Appendix C - Wire Gauge Charts
Stranded Cable Lgth.
(ft.)
5
10
40
80
Wire Gauge (AWG)
18
16
14
12
10
18
16
14
12
10
18
16
14
12
10
8
18
16
14
12
10
8
Power Loss
(8 ohm load)
0.81%
0.51
0.32
0.20
0.128
1.61%
1.02
0.64
0.40
0.25
6.2%
4.0
2.5
1.60
1.01
0.60
11.9%
7.7
5.0
3.2
2.0
1.20
Power Loss
(4 ohm load)
1.61%
1.02
0.64
0.40
0.25
3.2%
2.0
1.28
0.80
0.51
11.9%
7.7
5.0
3.2
2.0
1.20
22%
14.6
9.6
6.2
4.0
2.4
Power Loss
(2 ohm load)
3.2%
2.0
1.28
0.80
0.51
6.2%
4.0
2.5
1.60
1.01
22%
14.6
9.6
6.2
4.0
2.4
37%
26
17.8
11.8
7.7
4.7
Stranded Cable Lgth.
(m)
2
5
10
30
Wire Gauge (mm2)
0.3
0.5
0.75
1.5
2.5
4
0.5
0.75
1.5
2.5
4
6
0.5
0.75
1.5
2.5
4
6
0.75
1.5
2.5
4
6
10
Power Loss
(8 ohm load)
2.9%
1.74
1.16
0.58
0.35
0.22
4.3%
2.9
1.45
0.87
0.55
0.37
8.24%
5.6
2.9
1.74
1.09
0.73
15.5%
8.2
5.1
3.2
2.2
1.31
Power Loss
(4 ohm load)
5.6%
3.4
2.3
1.16
0.70
0.44
8.2%
5.6
2.9
1.74
1.09
0.73
15.5%
10.8
5.6
2.9
1.74
1.09
25%
15.5
9.8
6.3
4.3
2.6
Power Loss
(2 ohm load)
10.8%
6.7
4.5
2.3
1.39
0.87
15.5%
10.8
5.6
3.4
2.2
1.45
28%
19.9
10.8
6.7
4.3
2.9
45%
28
18.2
12.0
8.2
5.1
Appendix C Crest Audio HD Series Power Amplifiers
Models HD2, HD4, HD6, HD9, HD12, HD18
Page 21
Appendix D
Rear Panel Symbols - Legend
Input Connection Section
2+
1
3-
+
XLR Connector Polarity Indicator
A
AB
A
A
B
B
A
B
A
GAIN
40x
Ø
dBu
XLR Pin +
2 3
20x
TRS Connector Polarity Indicator
Mode Selection Switch - Bridged Mono Position
Mode Selection Switch - Parallel Position
Mode Selection Switch - Stereo Position
Chassis Ground Lift Switch - Grounded Lift Position
Chassis Ground Lift Switch - Grounded Position
Output Connection Section
A
B
A
B
A
Speakon Output Connector - Channel A Stereo/Parallel
Speakon Output Connector - Channel B Stereo/Parallel
Speakon Output Connector - Bridged Mono
5-Way Binding Post Output Connection - Channel A Stereo/Parallel
+
+
A
5-Way Binding Post Output Connection - Bridged Mono
B
+
B
Crest Audio HD Series Power Amplifiers Appendix D
Models HD2, HD4, HD6, HD9, HD12, HD18
5-Way Binding Post Output Connection - Channel B Stereo/Parallel
Page 22
Appendix E
HD18 Power Amplifier - Special Functions
The HD18 rear panel features external switches for the following:
XLR Pin+ Switch: This switch configures XLR input connection polarity. Either pin 2 or pin 3 may be
selected as the “hot” (+) pin. Amplifiers are shipped pin 2 “hot” (+) from the factory.
Gain Switch: This switch permits the amplifier to be configured for the standard input sensitivity (.775V
for rated power @ 8Ω), or for optional voltage gains of X40 or X20. Refer to the specifications for input
sensitivity values at optional voltage gains of X40 and X20.
NOTE: Two pairs of 5-way binding posts are provided for each channel, so that paralleling of speakers is
possible.
ALWAYS power down the amplifier before changing settings
with either the XLR Pin+ switch or the Gain switch!
HD18 - Rear View
Designed & manufactured in the USA by:
Paramus, New Jersey 07652 USA
A
A
+
+
A
B
+
B
AB
A
B
A
A
A
XLR Pin (+) Switch
Crest Audio Inc.
100 Eisenhower Dr.
+
XLR Pin +
B
2 3
B
GAIN
40x
Ø
20x
dBu
A
B
1
2
3
Gain Switch
Appendix E Crest Audio HD Series Power Amplifiers
Models HD2, HD4, HD6, HD9, HD12, HD18
Page 23
Three-Year Power Amplifier Warranty
Warranty Information.
Crest Audio Inc. warrants to the original purchaser of any HD Series Crest Audio Amplifier purchased at an
Authorized Crest Audio dealer, that it will be free from defects in material and workmanship for a period of
three (3) years from the date of purchase.
Crest Audio, its distributors, or one of its authorized Service Centers will, at its option, repair or replace any
unit or component covered by this warranty which becomes defective or malfunctions under normal use/service during the period of this warranty, at no charge for parts or labor to the original owner.
This warranty does not cover damage from shipping accidents, misuse, abuse, operation with incorrect AC
voltage, operation with faulty associated equipment, modification, or alteration without prior factory
approval, service by an unauthorized Service Center, and normal wear and tear. Units on which the serial
number has been removed or defaced are not eligible for warranty service. Evidence of alteration, erasing,
or forgery of proof-of-purchase documents will be cause to void the warranty. Any implied warranties,
including warranties of merchantability and fitness for a particular use, shall be limited in duration to the
period of time set forth above. Crest Audio is not responsible for any incidental or consequential damages
with respect to the products warranted. Some states or provinces do not allow limitations on how long an
implied warranty lasts, or do not allow the exclusion or limitation of incidental or consequential damages,
so the above limitations or exclusions may not apply to you. This warranty gives you specific legal rights;
you may have other legal rights that may vary from state to state (or province to province).
For warranty service, the equipment and a photocopy of the original Bill of Sale should be delivered at the
owner’s expense to an Authorized Crest Audio Service Center or to Crest Audio at the address on the back
cover of this manual. Collect shipments will not be accepted. Original equipment boxes should be used for
shipping. If the original boxes are not available, replacement shipping boxes may be ordered from Crest
Audio at the customer’s expense.
The names and addresses of Authorized Crest Audio Service Centers are available from Crest Audio dealers
and distributors, or by contacting the factory directly. If the equipment is returned to Crest Audio or one of
its Service Centers, and is determined by Crest Audio to be under warranty, the equipment will be returned
after servicing, regular surface freight prepaid, to the original owner or dealer. Crest Audio Inc. reserves the
right to make changes or improvements in design or manufacturing without assuming any obligation to
change or improve products previously manufactured.
Crest Audio HD Series Power Amplifiers Appendix F
Models HD2, HD4, HD6, HD9, HD12, HD18
Page 24
Choice of touring professionals.
Crest Audio Inc.
100 Eisenhower Dr., Paramus NJ 07652 USA
TEL: 201.909.8700 FAX: 201.909.8744
http://www.crestaudio.com
Printed in USA
C4400001
v. 1.2 10/22/97
© 1997 Crest Audio, Inc.
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