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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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