Crest audio HD4 SPECIFICATIONS

POWER AMPLIFIER

HD4

Product Description

The Crest Audio HD4 professional power amplifier is designed
to achieve unsurpassed sonic performance and long-term reliabil­ity–even when operating under extreme stress–in touring or fixed
installation applications.

Absolute sonic accuracy is the hallmark of every Crest amplifier.
Bass is solid and defined to the limits of audibility, with ample
current reserves delivered by an “over-engineered” power supply
and advanced Class AB output circuit design. Wide-bandwidth
output devices assure detailed, transparent high frequency
response. And, thanks to Crest’s exclusive IGM circuit, the HD4
will drive 2Ω loads

safely without compromise in performance.

Construction and Quality Control

The HD4 is built exclusively in Crest’s own USA manufacturing
facility, with internal components selected for premium quality
and proven durability. Each modular subassembly is pre-tested,
and the assembled HD4 receives a rigorous “hot room” burn-in
before thorough final checkout on precision test equipment.

Power Specifications:
Other HD Series Power Amplifiers

4Ω Stereo HD2 HD6 HD9 HD12 HD18

1kHz, .01% THD+N 250W 600W 900W 1200W 1800W
20Hz-20kHz, 0.1% THD+N 200W 500W 800W 1100W 1700W

HD4 Features

• Crest’s legendary “overbuilt” power supply

• Toroidal power transformer

• Latest generation of high-speed, wide-bandwidth output
devices

• Twin Tunnel Cooling with back-to-front air flow

• Dual, variable speed DC fans

• Massive, extruded aluminum heat sinks

• Balanced XLR and 1/4-inch (TRS) inputs

• 5-Way binding post outputs

• Stereo/Parallel/Bridged Mono mode selector switch

• Ground lift switch

• TourClass®protection circuits:

- ACL (Active Clip Limiting) prevents speaker damage with
gentle gain reduction at clip threshold.

- IGM (Instantaneous Gain Modulation) monitors connected
loads to detect conditions that may overstress output
devices, allowing safe operation into nominal 2Ω imped­ances.

- AutoRamp gradually increases gain to attenuator setting
level when amplifier is turned on.

- TourClass also includes comprehensive thermal manage­ment, and short circuit, DC voltage, turn-on/off transient,
current inrush and sub/ultrasonic input protection.

• Input sensitivity selection

• Recessed, stepped attenuators

• Front panel magnetic circuit breaker switch

• Modular construction

• Three-year warranty (parts and labor)

Protect

Clip

Active

Signal

Ch A

Protect

Clip

Active

Signal

Ch B

Power Specifications 8Ω Stereo 4Ω Stereo 2Ω Stereo 8Ω Bridged 4Ω Bridged

1kHz, 0.01% THD+N 250W 435W 500W 830W 1100W
20Hz-20kHz, 0.1% THD+N 245W 400W 450W 800W 900W

-6

-10

-3

-15

-30

-80

-10

-15

-30

-80

-1

0dB

-6

-3

-1

0dB

Figures are Watts per channel, both channels driven.

HD4 POWER AMPLIFIER

SPECIFICATIONS

1kHz, 0.01% THD+N 20Hz-20kHz, 0.1% THD+N

8Ω Stereo Power
4Ω Stereo Power

2Ω Stereo Power
8Ω Bridged Mono Power
4Ω Bridged Mono Power

Max RMS Output Voltage

(each channel)

Peak Output Voltage (each channel)

Frequency Response (+0 / -0.3dB, 1W/8Ω)

Power Bandwidth (rated power at 4Ω, 1% THD+N)

TourClass®Protection

THD+N

(rated power at 4Ω, 1kHz)

SMPTE IMD (rated power at 8Ω, 60Hz & 7kHz)

Damping Factor (10-400Hz at 8Ω)

Input CMRR (1kHz)

Input Sensitivity (rated power at 8Ω )

Voltage Gain

Input Impedance (balanced/unbalanced)

Hum and Noise

(“A” weighted, full power, 4Ω)

Crosstalk (“A” weighted, full power, 4Ω)

Input Connectors

(per channel)

Output Connectors (per channel)

Filter Storage

Power Supply

(factory configured)

Idle Current Draw 120V

1/8 Power Curr. Draw

(typical music, 120V/4Ω)

1/3 Power Curr. Draw (continuous music, 120V/4Ω)

Max Curr. Draw (circuit breaker rating, 120V/4Ω)

Thermal Emissions (1/8 Power, 4Ω)
Thermal Emissions (1/3 Power, 4Ω)

Controls

LED Indicators

(per channel)

Construction

Dimensions

(Height x Width x Depth)

Gross Weight, Net Weight

Warranty

Dealer-Configurable Gain/Sensitivity Options Factory Standard X61 .775V

250W 245W
435W 400W
500W 450W
830W 800W
1000W 900W
58V
82V
20Hz-20kHz, -3dB@135kHz
20Hz-20kHz, -.9dB/+.5dB
ACL, IGM, AutoRamp, short circuit, DC voltage,
turn-on/off transient, current inrush, sub/ultrasonic input.
<0.01%
<0.01%
550:1
> - 60dB

0.775V standard (see table below)
X61 standard (see table below)
>20kΩ/>10kΩ

-105dB
> - 60 dB

Class

AB
Female XLR (pin 2+, dealer configurable for pin 3+), TRS (tip+)
5-way output binding posts or Speakon connectors
27,200 µF
100V-240V, 50-60Hz

1.4A

6.8A

10.0A
15A
2030 BTU/hr
2726 BTU/hr

Cooling

Back-to-front via 2 rear panel mounted variable-speed DC fans
(filters removable without tools)
Front Panel: 2 attenuators
Rear Panel: signal ground lift switch, mode select switch
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
46 lbs. / 20.88 kg., 41 lbs. / 18.61 kg.
3 years, parts & labor

Gain Sens

Option 1 X40 1.12V
Option 2 X20 2.24V

(market dependent)

Architect’s & Engineer’s Specifications

The power amplifier shall have two channels. At 8 ohms, 20Hz ­20kHz, 0.1% THD+N, it shall deliver a minimum of 245 Watts per
channel. At 4 ohms, 20Hz - 20kHz, 0.1% THD+N, it shall deliver a
minimum of 400 watts per channel. In bridged mono mode with an
8 ohm load, 20Hz - 20kHz, 0.1% THD+N, it shall deliver a mini­mum of 800 watts.
Two rear panel mounted variable speed DC fans (filters detachable
without tools) shall provide back to front air flow through the chas­sis.
The amplifier shall have circuitry to protect itself from output short
circuits, thermal overload or other adverse load conditions. The
amplifier shall protect speaker loads from DC voltage on outputs.
The amplifier shall have active clip limiting and impedance sensing
circuitry. Output relays shall protect the speakers from amplifier
failure.
Each channel shall have a standard (factory-set) input sensitivity of

0.775 Volts, and shall be fitted with an internal jumper which
allows the gain to be altered to X20 or X40. The hum and noise
level shall be 105 dB below rated output, “A” weighted.

IMD shall be less than 0.01% at rated power, 60Hz and
7kHz. The amplifier shall have a class AB output stage. The fre-

quency response shall be 20Hz-20kHz, +0, -0.3dB at rated power.
The amplifier will operate at 100V-240V, 50-60 Hz AC (configured
at factory). Maximum current draw shall not exceed 15 amperes at
120VAC (limited by front panel breaker for bench tests).
Front panel indicators shall include Active, Protect, Signal, and
Clip LED’s for each channel. Front panel attenuators shall be
recessed and detented.
Rear panel input connectors shall be female TRS and XLR type,
internally dealer-configurable for pin 2 (factory setting) or pin 3
positive. Output connectors shall be 5-way output binding posts. A
ground lift switch and a Stereo/Parallel/Bridged Mono mode oper­ation switch shall be provided.
A rear-panel IEC AC mains socket (with power cord) or single AC
mains cord having an appropriate AC plug for the intended operat­ing voltage shall be provided (market dependant).
The packaging of the amplifier shall allow for standard rack
mounting without requiring space between similar units. Optional
rack mount handles will be available. Dimensions shall be 19"
(483mm) wide, 3.5" (89mm) high and 18" (457mm) deep. The
amplifier shall weigh 43 lbs. (19.52 kg.) net, and shall be designat­ed the Crest Audio model HD4.

SMPTE

Rear View

v. 1.1 5/21/97 C3400002

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

Power figures are watts per channel, both channels driven.
Crest Audio reserves the right to make improvements in manufacturing or

design which may affect specification. Crest Audio specification literature
is available in electronic form to qualified users. Contact Crest Audio Inc.
for more information. © 1997 Crest Audio Inc.

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Designed & manufactured in the USA by:

Crest Audio Inc.

100 Eisenhower Dr.

Paramus, New Jersey 07652 USA

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Crest Audio Inc.

100 Eisenhower Dr., Paramus NJ 07652 USA

TEL: [phone] FAX: [phone]

http://www.crestaudio.com

Printed in USA