Crest Audio PRO SERIES 4601 User manual

Product Description
The Crest Audio Model 4601 power amplifier is a compact,
medium-power amplifier designed to meet the demands of con-
cert touring, studio monitoring, high-quality sound reinforce-
ment, and professional installations.
Crest Audio developed this model in conjunction with the
biggest names in touring sound. These amplifiers meet the spe-
cific demand for medium-power amplifiers with full-range capa-
bilities, but optimized for mid- and high-frequency applications.
The output section operates purely in Class AB, with no dynamic
switching of supply rail voltages. The result is the cleanest, most
transparent mid-and high-frequency audio power imaginable
from amplifiers that never compromise quality.
A forced-air configuration is used to cool channel heat sinks
mounted in a back-to-back tunnel arrangement. An actively bal-
anced female XLR input connection, Octal Socket, and 5-way
output binding posts are provided for each channel.
The 4601 is fully compatible in design with other Crest Audio
Professional Series amplifiers, Octal Socket Accessories, and the
NexSys®computer-controlled audio system.
Design and Construction
The 4601 is built exclusively in Crest Audio’s own USA manu-
facturing facility, with internal components selected for premium
quality and proven durability. Each modular subassembly is pre-
tested, and the assembled 4601 receives a rigorous “hot room”
burn-in before thorough final checkout on precision test equip-
ment.
Only high-grade components are used for the modular sub-
assemblies in this ultra-strong, steel single piece chassis.
4601 Features
• Crest Audio’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
• High thermal mass heat sinks
• Balanced XLR inputs
• 5-way output binding post connectors
• Stereo/Parallel/Bridged Mono mode selector switch
• Rear panel ground lift jumper
• 4601 protection circuitry:
- 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.
- AutoRamp gradually increases gain to attenuator setting
level when amplifier is turned on.
- Other protection circuitry: comprehensive thermal manage-
ment, and short circuit, DC voltage, turn-on/off transient,
current inrush and sub/ultrasonic input protection.
• Recessed, stepped attenuators
• Front panel circuit breaker/power switch
• Modular construction
• Five-year warranty (USA, Canada, U.K. & many other countries).
Power Specifications 8ΩStereo 4ΩStereo 8ΩBridged
1kHz, 0.012% THD+N 350W 485W 925W
20Hz-20kHz, 0.05% THD+N 300W 425W 825W
Figures are Watts per channel, both channels driven.
®Crest Professional Series Amplifiers are
fully compatible with the NexSys
Computer-Controlled Audio system.
4601
POWER AMPLIFIER

1kHz, <0.012% THD+N 20Hz-20kHz, <0.05% THD+N
350W 300W
485W 425W
925W 825W
59V
83.4V
20 Hz-20 kHz, -3dB @ 53kHz
20 Hz-20 kHz, +0/-0.2dB
Clip Limit, IGM, AutoRamp, High Temp, short-circuit,
DC voltage, turn-on/off transient, sub/ultrasonic input.
<0.012%
<0.1%
400:1
>60 dB
1.03V RMS
X40
>20kΩ
> -100 dB
> -60dB
AB
Female XLR (pin 3+), Octal Socket
5-way output binding posts
40,800 µF
100V-240V, 50-60Hz
1.1A
7.3A
11.1A
18.0A
2576 BTU/hr
3443 BTU/hr
Rear to front tunnel heatsink, 2 variable speed DC fans
Front panel: 2 attenuators, circuit breaker/power switch;
Rear panel: mode switch, signal ground lift jumper.
Clip/Limit, Signal, Temp/DC, Active
16 ga. single piece steel chassis, .187" (5mm) alum. front panel
3.5"x19"x15" (16" to rear ears)
89mm x 483mm x 381mm (406mm to rear ears)
48.0 lbs (21.79 kg.), 43.0 lbs (19.52 kg.)
5 years, parts and labor†
8ΩStereo Power
4ΩStereo Power
8ΩBridged 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)
Protection Circuitry
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 4Ω)
Voltage Gain
Input Impedance (balanced)
Hum and Noise (“A” weighted, full power, 4Ω)
Crosstalk (“A” weighted, full power, 4Ω)
Class
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)
Cooling
Controls
LED Indicators (per channel)
Construction
Dimensions (Height x Width x Depth)
Gross Weight, Net Weight
Warranty
† USA, Canada, U.K., and many other countries. Power figures are watts per channel, both channels driven. CrestAudio reserves the right
to make improvements in manufacturing or design which may affect specifications. Crest Audio specification literature is available in
downloadable PDF file format; visit our website at http://www.crestaudio.com. ©1997 Crest Audio Inc. 5/21/97
v. 2.4 4/9/97 B5100002
Crest Audio Inc.
100 Eisenhower Dr., Paramus NJ 07652 USA
TEL: [phone] FAX: [phone]
http://www.crestaudio.com
Printed in USA
4601 POWER AMPLIFIER
SPECIFICATIONS Architect’s & Engineer’s Specifications
The power amplifier shall have two channels. Each chan-
nel shall deliver a minimum of 300 watts at 8 ohms and
425 watts at 4 ohms; 20Hz - 20kHz, <0.05% THD+N. In
bridged mode, it shall deliver 825 watts at 8 ohms, 20Hz
20kHz, <0.05% THD+N.
The amplifier shall be rear-to-front tunnel-cooled, with two
variable-speed DC fans.
It shall have circuitry to protect itself and the speaker load
from output short circuits, DC voltage on outputs, and
thermal overload. The amplifier shall have RMS clip limit-
ing and impedance sensing circuitry. Output relays shall
protect the speakers from any type of amplifier failure.
The amplifier shall have a voltage gain of X40 with an
input sensitivity of 1.03V for rated power at 4 ohms. The
hum and noise level shall be at least 100 dB below rated
output, “A” weighted. SMPTE IMD shall be less than
0.1% at rated power, 60Hz and 7kHz. The amplifier shall
have a class AB output stage with a modulated power sup-
ply. The frequency response shall be greater than 20Hz-
20kHz, + 0, -0.3dB (1W/8Ω).
The amplifier shall operate at either 100, 120, 220, or 240
volts, 50-60 Hz AC (configured at factory). Maximum cur-
rent draw shall not exceed 18 amperes at 120VAC or 11
amperes at 240VAC, (limited by front panel breaker for
bench tests), with both channels driven continuously into a
4 ohm resistor.
The amplifier front panel shall include Active, Temp/DC,
Signal Present and Clip/Limit LED indicators for each
channel, a combination power switch/magnetic circuit
breaker and recessed and detented gain pots.
Rear panel inputs shall be actively balanced and have
female XLR-type, 3-pin connectors (pin 3+). Output con-
nectors shall be 5-way output binding posts. Octal sockets
for optional accessory modules and a signal/ground lift
jumper shall be provided.
A rear-panel AC mains cord having an appropriate AC
plug for the intended operating voltage shall be provided
(market dependent).
The packaging of the amplifier shall allow for standard
rack mounting without requiring space between similar
units. Dimensions shall be 3.5" (89mm) high x 19"
(483mm) wide x 15" (381mm) deep. The amplifier shall
have a net weight of 43.0 lbs. (19.52kg). The amplifier
PUSH
PUSH
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 CETAPPAREIL SOUS LA PLUIE OU Á
L'HUMIDITÉ
RISK OF ELECTRIC SHOCK
DO NOT OPEN
CAUTION
AVIS : RISQUE DE CHOC ÉLECTRIQUE—NE PAS OUVRIR
USA ONLY
MODEL #
4601 18 AMPS
MAXIMUM
INPUT CURRENT
@ 120V, 60Hz
OUTPUT POWER
IN WATTS PER
CHANNEL, 4Ω
425W
OUTPUT - CLASS 2 WIRING MAY BE USED
Designed & manufactured in the USA by:
Crest Audio Inc.
100 Eisenhower Dr.
Paramus, New Jersey 07652 USA
IN B
IN A
PIN 3+ A
B
STEREO
BRIDGE
PARALLEL
SIGNAL
GROUND
LIFT
OUT A
+
BRIDGE
--
OUT B
Rear View
*B5100002*