481QE
321QE & 481QE AMPLIFIER OWNER’S MANUAL
(MODE D’EMPLOI)
877 COUSTIC COUSTIC.COM
WELCOME
. . . to the Coustic world of power and clarity. These new Coustic 321QE and 481QE 4-channel
power amplifiers deliver the cleanest music you’ve ever heard at any power level in the 12-volt
environment.
Besides their sleek contoured design, the new 321QE/481QE power amplifiers offer the latest
and most sophisticated audio features. This manual offers you a guided tour of all these exciting
features. For the best sonic reproduction, please follow the installation suggestions and recommen-
dations as closely as possible. The time you spend will prove to be worthwhile when you sit back
and enjoy the high fidelity music!
To further explore the potential of your Coustic amplifier, we recommend you match it with our
dynamic full-range speakers or subwoofers and electronic crossovers.
Whatever you need for your ultimate car audio system, look to Coustic - for a wide range of car
audio components to meet the most critical demands.
Coustic . . . a sound investment.
No part of this publication may be reproduced, stored in a retrieval system or transmitted, in any
form or by any means, electronically, mechanically, or otherwise, without the prior written permis-
sion of Coustic or Mitek Corporation.
Please take a moment to register your purchase on line @ coustic.com.
Please also record the serial number of your amplifier in the space provided below and keep this
manual for future reference, as well as your sales receipt as proof of ownership. (The serial num-
ber of your amplifier is marked on the bottom of its metal chassis.)
Serial Number:
Date of Purchase:
FEATURES
BUILT-IN ELECTRONIC CROSSOVER WITH CONTINUOUSLY ADJUSTABLE
CROSSOVER FREQUENCIES
An electronic crossover has many advantages over passive crossovers - lower cost, simplified yet
more flexible system design, lower distortion and higher gain structure. The 321/481QE power
amplifiers are equipped with built-in 18dB per octave continuously adjustable electronic
crossovers. The front and rear channels can be configured separately for full-range, high-pass or
low-pass applications.
OVER-CURRENT, SHORT CIRCUIT AND DC OFFSET PROTECTION
The sophisticated circuitry monitors abnormal conditions such as voltage spikes, oscillation, DC off-
set or short circuit. When any of these undesirable conditions exceed their respective preset limits,
the circuit will shut down the audio system briefly and lights up the protection indicator to identify
the problem for immediate attention. Once the problem is resolved, the amplifier will resume oper-
ation automatically.
HIGH SPEED HIGH CURRENT MOSFET SWITCHING POWER SUPPLY
High current MOSFET transistors are used in the power supply section to minimize internal heat
and maximize reliability. Furthermore, the combination of the very high pulse-width-modulated
(PWM) switching frequency and the extra large filter capacitance guarantees stronger and deeper
transient bass response.
TRIPLE DARLINGTON HIGH CURRENT/HIGH VOLTAGE FULLY COMPLEMENTARY
OUTPUT STAGE
Complementary output stage audio circuitry has long been a hallmark of "exotic" home amplifier
design. Coustic is one of the very few car audio manufacturers to incorporate such elaborate
audio circuitry into its power amplifiers. Triple Darlington configuration ensures the audio amplifier
is always operating at its optimum conditions.
LINE OUPTUTS
The full-range line outputs can be used to feed signals to another amplifier for your future expan-
sion or for setting up a more sophisticated system.
WIDE RANGE INPUT SENSITIVITY ADJUSTMENT
The input sensitivity level of the Coustic 321/481QE amplifiers can be easily varied from as low
as 100 mV to as high as 5.0 volts by adjusting the control on the Input Panel.
LINE LEVEL AND SPEAKER LEVEL INPUTS
These ampliifers feature pre-amp inputs for use with head units that have RCA or line level outputs.
These amplifiers also feature speaker level inputs allowing the amplifier to work with head units
that do not have RCA or line level outputs. The audio signal can be obtained by simply connect-
ing the amplifiers speaker level input wires to the head units speaker level outputs wires. If you are
using a floating or common ground car radio, this amplifier is the best fit for your system. It is com-
patible with floating or common ground car radio speaker outputs even without a floating ground
adapter.
ADJUSTABLE BASS BOOST
This feature allows you to enhance the bass performance of your sound system. The control is con-
tinuously variable with a maximum boost level of 18dB.
REMOTE SUBWOOFER GAIN CONTROL PORT (R S)
The 481QE amplifier has a built-in remote subwoofer level control input port. With the optional
R S remote control, the subwoofer output level can be adjusted to compensate for bass fluctuations
in a moving vehicle.
MULTI-FUNCTION PROTECTION INDICATOR
When the red protect indicator lights up it signifies a high operating temperature is detected and
the amplifier is temporarily shut down to allow for a cooling period. As soon as the temperature
returns to a safe level, the amplifier will restart and resume normal operation.
This indicator also lights up when the amplifier detects either an over-current situation, shorted
speaker outputs or a DC offset at the outputs. Turn off the amplifier, double-check all inputs and
speaker connections to make sure there is no short or inappropriate inputs. If all connections are in
order, turn on the amplifier to resume operation.
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CONTROLS, INDICATORS, AND TERMINALS
INPUT PANEL
Figure 1: Input Panel Terminals and Controls
1. FRONT CHANNEL FILTER MODE SELECT SWITCH (MODE)
"HPF": Slide switch to this position if the amplifier is used as a mid/tweeter amplifier.
"OFF": Slide switch to this position if the amplifier is used as a full-range amplifier.
"LPF": Slide switch to this position if the amplifier is used as a subwoofer amplifier.
2. FRONT CHANNEL HIGH-PASS/LOW-PASS FREQUENCY SELECTOR KNOB (FREQ)
Select a high/low-pass crossover frequency between 30Hz to 300Hz.
3. FRONT CHANNEL BASS BOOST CONTROL (BOOST)
Select a boost level between 0dB and +18dB to enhance the bass performance of your sound
system.
4. FRONT CHANNEL INPUT SENSITIVITY LEVEL CONTROL (SENS)
The input sensitivity level can be varied from 5.0 volts to 100 mV depending on the output volt-
age of the source unit (refer to sub-section titled INPUT SENSITIVITY ADJUSTMENT).
5. FRONT CHANNEL HIGH IMPEDANCE INPUT
To be connected to RCA pre-amp outputs from a source unit (i.e., radio, tape deck or CD player).
6. FRONT/REAR CHANNEL LOW IMPEDANCE INPUT
To be connected to speaker outputs from a source unit when pre-amp outputs are not available.
7. LINE LEVEL OUTPUT
This output can be used to connect to another amplifier for system expansion.
Note: This line level output is full range.
8. REAR CHANNEL FILTER MODE SELECT SWITCH (MODE)
"HPF": Slide switch to this position if the amplifier is used as a mid/tweeter amplifier.
"OFF": Slide switch to this position if the amplifier is used as a full-range amplifier.
"LPF": Slide switch to this position if the amplifier is used as a subwoofer amplifier.
9. REAR CHANNEL HIGH-PASS/LOW-PASS FREQUENCY SELECTOR KNOB (FREQ)
Select high/low-pass crossover frequency between 30 Hz to 300Hz.
10. REAR CHANNEL BASS BOOST CONTROL (BOOST)
Select a boost level between 0dB and +18dB to enhance bass performance of your sound
system.
11. REAR CHANNEL INPUT SENSITIVITY LEVEL CONTROL (SENS)
The input sensitivity level can be varied from 5.0 volts to 100 mV depending on the output
voltage of the source unit (refer to sub-section titled INPUT SENSITIVITY ADJUSTMENT).
12. REAR CHANNEL HIGH IMPEDANCE INPUT
To be connected to RCA pre-amp outputs from a source unit (i.e., radio, tape deck or CD
player). If there is only one input available, connect it to the front input so that signals can
automatically be directed to the rear channels.
13. REMOTE SUBWOOFER GAIN INPUT (not available on 321QE)
To be connected to the optional R S remote subwoofer volume control.
OUTPUT PANEL
Figure 2: Output Panel Terminals and Indicators
14. POWER AND PROTECT INDICATOR (PWR/PRT)
Green light indicates that the amplifier is "ON." Red light indicates either a high current,
short circuit or DC offset is detected at the speaker outputs. The amplifier will revert to normal
operation once the problem is rectified. The red indicator also lights up at a high operating
temperature. Under this condition, the amplifier will automatically shut down. As soon as the
temperature falls to a safe level, the amplifier will automatically resume operation.
15. POWER INPUT TERMINAL (B+)
To be connected to the positive terminal of the vehicle’s battery or other constant +12 V
source.
16. GROUND INPUT TERMINAL (GND)
To be wired to the vehicle’s chassis for ground.
17. REMOTE TURN-ON INPUT TERMINAL (REM)
To be connected to the remote control wire or power antenna lead of the source unit for
remote ON/OFF.
18. FUSE RECEPTACLE
19. FRONT CHANNEL LEFT/RIGHT SPEAKER OUTPUT TERMINAL
For connection to the front speaker system.
20. REAR CHANNEL LEFT/RIGHT SPEAKER OUTPUT TERMINAL
For connection to the rear speaker system.
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FRONT
REAR
SPKR LEVEL
L
R
REMOTE
SENS
MIN MAX
MODE
HPF OFF LPF
FREQ
30 300
60 180
0 +18
BOOST
SENS
MIN MAX
MODE
HPF OFF LPF
FREQ
30 300
60 180
0 +18
BOOST
OUTPUT FRONT REAR
INPUT
7
512
1
2 8
9
6
4
3
11
10 13
FUSE
PWR /PRT
GND REM B+
1417 1516 18
19
+ L - + R -
BRIDGE
BRIDGE
+ L - + R -
FRONT
REAR
20
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INSTALLATION
By purchasing the 4-channel 321QE/481QE amplifier, you are already one step closer to experi-
encing the purest and most natural sound quality in the automobile environment. To take full advan-
tage of the potential of this amplifier, before installation, we strongly recommend that you acquaint
yourself with all its available features and then spend some time in designing a system most suit-
able for you. Take into consideration the components you have now and those that you plan on
adding or upgrading in the future.
The 321QE/481QE power amplifiers are designed for use with a 12-Volt negative ground system.
Installing this amplifier in a vehicle with a POSITIVE ground system will result in severe damage to
the amplifier, other audio components and/or the vehicle’s electrical components. If your vehicle
happens to run on a positive ground system, please consult your Coustic dealer.
Caution: Please follow all the installation recommendations and instructions in this manual. Installing
and/or using the amplifier in methods other than those outlined herein may reduce the perform-
ance capability of the amplifier. Any such installation or usage renders the product
warranty void.
Warning: The battery ground should remain DISCONNECTED at all stages of installation.
LOCATION
Ventilation: The primary deciding factor of amplifier location is heat dissipation. Despite its highly
efficeint heat dissipation design, the amplifier can be crippled by inadequate ventilation. Prolonged
operation at high volumes, combined with inadequate ventilation, may cause the amplifier to over-
heat and trigger the automatic shut down circuit until the temperature returns to a safe level. To
ensure adequate ventilation, the ideal location for the amplifier is a spot away from any heat
source, with at least 2 inches of clearance above and around the unit.
Figure 3: Upright Mount on Horizontal Surface Figure 4: Parallel Mount on Vertical Surface
The amplifier may be mounted upright on a horizontal surface (see Figure 3) or parallel to a verti-
cal surface (see Figure 4). However, the amplifier should never be mounted upside down (see
Figure 5) for the simple reason that the hot air generated by the amplifier would have to go
through the unit internally on its natural upward path (i.e., "feedback" into the unit) and would
result in increased internal temperature. This would speed up the thermal shut down of the
amplifier.
Figure 5: Inverted Mount
(Not Recommended)
Vibration: Constant vibration could eventually cause the amplifier to come off from mount, resulting
in stress on wire connections, which, in turn, results in "open" or "short" circuit. For this reason, a
location with minimum vibration and a flat surface for secure and firm mounting should be chosen
for the amplifier.
Moisture: The amplifier should never be exposed to moisture and water.
Taking all the above into consideration, the best mounting position for the amplifier would be the
floor of the trunk or behind the rear seat back.
Once the location of all the components has been determined, plan the best routes for all the nec-
essary wiring, making sure that the wires are easily accessible without dismounting the various
components.
MOUNTING
1. Place the amplifier at the desired location and use it as a template to determine the exact posi-
tion of the mounting holes.
2. Mark the mounting holes with a felt pen.
3. Put the amplifier aside.
4. If the mounting surface is carpeted, cut out small circles of the carpet and padding around the
four mounting holes to expose the metal underneath.
5. Use a center punch to ensure drilling the exact position for the screws. DO NOT BEGIN
DRILLING UNTIL YOU HAVE PUT THE AMPLIFIER ASIDE. USING THE AMPLIFIER AS A
DRILLING GUIDE MAY CAUSE IRREPARABLE DAMAGE TO THE AMPLIFIER.
6. Mount the amplifier with the screws provided.
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CD-328
CD Changer Control
+
R
+
321QE/481QE
Coustic
Coaxial
Coustic
Coaxial
+
R
(crossover set to OFF position)
Front
Rear
CD-328
CD Changer Control
+
R
321QE/481QE
+
Coustic
Coaxial
Coustic
Subwoofer
+
R
(crossover: front set @ 100Hz Hi-Pass, rear set @ 100Hz Lo-Pass)
Front
Rear
Figure 7.Typical High/Low Pass System with one amplifier
CD-328
+
R
+
321QE/481QE
Coustic
Coaxial
Coustic
Coaxial
Coustic
Subwoofers
+
R
+
R
401SE
(crossover: front set to 100Hz Hi-Pass
rear set to 100Hz Hi-Pass)
Front
Rear
(crossover set to 100Hz Lo-Pass
Figure 8.Typical High/Low Pass System with two (2) amplifiers
Figure 6.Typical Full Range System
BI-AMPLIFICATION
A bi-amplified system normally consists of an active crossover and two amplifiers. The active
crossover divides the audio frequency spectrum into two ranges: frequencies below the crossover
point are directed to the amplifier driving the subwoofer(s), while all frequencies above the
crossover point are directed to the amplifier driving the mid-range/tweeters.
FOR BRIDGED (MONO) MODE
Note: For bridged mono mode, we recommend a total load of 4 or 8 ohms.
1. Connect the front left positive ("+") speaker output of the amplifier to the positive input terminal
of the speaker.
2. Connect the front right negative ("–") speaker output of the amplifier to the negative input termi-
nal of the speaker.
3. Repeat the same for the rear channel.
4. Make sure that ALL RCAs (front and rear left/right) are plugged in, other wise bass response
and output will suffer.
Figure 11: Bridged Single Woofer Connection
CAUTION: ANY DEVIATION FROM THE ABOVE SPEAKER CONNECTION MAY CAUSE
SERIOUS DAMAGE TO THE AMPLIFIER AND/OR SPEAKERS. PLEASE DOUBLE CHECK THE
CONNECTION BEFORE TURNING THE SYSTEM ON.
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INSTALLATION continued
INPUT CONNECTIONS
Connect the front and rear RCA input jacks of the Amplifier to the outputs of the Source Unit (i.e.,
radio, cassette player or CD player). If line level output is not available, connect the speaker out-
puts of the source unit to the Speaker Level input of the amplifier.
Figure 9: High/Low Impedance Inputs
Note: Connect the black ground wire to the source unit ground only if alternator noise is
present.
Connect the Amplifier to the Speakers. Use thicker speaker wires (e.g. 8 - 10 gauge desirable) for
these connections.
FOR STEREO MODE
Note: We recommend a total speaker load of 2, 4 or 8 ohms per channel
1. Connect the front left negative ("–") speaker output of the amplifier to the negative terminal of
the left speaker.
2. Connect the front left positive ("+") speaker output of the amplifier to the positive terminal of
the left speaker.
3. Connect the front right ("–") speaker output of the amplifier to the negative terminal of the right
speaker.
4. Connect the front right ("+") speaker output of the amplifier to the positive terminal of the right
speaker.
5. Repeat the same for the rear channel speaker connections.
Figure 10: Stereo Connection
+ L - + R -
BRIDGE
BRIDGE
+ L - + R -
FRONT
REAR
+ L - + R -
BRIDGE
BRIDGE
+ L - + R -
FRONT
REAR
RIGHT REAR(green) +
FRONT
SPKR LEVEL
L
R
SENS
MIN MAX
MODE
HPF OFF LPF
OUTPUT FRONT REAR
INPUT
LEFT FRONT(wht/blk) -
LEFT FRONT(white) +
RIGHT FRONT(blu/blk) -
RIGHT FRONT(blue) +
LEFT REAR(yel/blk) -
LEFT REAR(yellow) +
RIGHT REAR(grn/blk) -
GROUND (black)
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