Acoustic Energy Acoustic Image Stereo Amplifier - Manual (Page 3)

1
Welcome to Acoustic Image!
You have purchased a state-of-the-art musical instrument amplifier system,
combining purity, power and portability in a package that sets a new standard
in high fidelity amplification.
Each of our designs is engineered to accurately reproduce the sound of
acoustic and electric instruments, delivering flat frequency response across
the entire musical spectrum; extended, tight, well-controlled bass; and
complete clarity of sound reproduction.
This manual provides operating information for your Acoustic Image Contra,
Coda R and Corus combo amp or Contra EX extension speaker cabinet.
The Basics
Our combo amps all use the same superb class-D 400-watt (4 ohms) power
amplifier, the same compact three-way speaker system (also used in the
Contra EX, but the speaker configuration of the Corus is slightly different) and
the same sophisticated, sensitive preamplifier. The features of the preamp and
the speaker configuration define the specific combo model.
The power amp is a high efficiency design that requires no external heat sinks
or cooling fans and is capable of driving loads as low as 2 ohms. AC power and
output speaker jacks are located on the rear of the enclosure. A standard,
three-prong detachable AC power cord is used to provide power to the unit,
while AC voltage selection switch allows the unit to operate at 115V/60 Hz or
230V/50 Hz. Japan models operate at 100V, 50/60 Hz only. See the rear panel
of your amp to verify the AC voltage capability.
The Contra combo is equipped with a one-channel preamp, the Coda R adds a
second, identical channel and a six-program effects unit. The Corus combo
has the same preamp as the Coda R but uses a different speaker system that
gives it a somewhat different sound from the other combos. The input channels
of both preamp types incorporate combo jack interfaces that allow either a high
impedance instrument input (to optimize the sound of piezo-type pickups) or a
mic input,
an effects loop with return level control, a
selectable notch/low cut filter for feedback control and reduction of low
frequency boominess, a direct out capability with ground lift and pre/post EQ
switch, a master level control and a mute switch. The two-channel preamp of
the Coda R and Corus has a switch that allows the second channel to be
disconnected from the main amp and connected to a satellite power amp to
create a stereo system.
All of our speaker enclosures incorporate a 10-inch downfiring woofer, a 5-inch
frontfiring midrange, and a 1-inch defeatable tweeter. The Corus uses a
different woofer that gives it a sound that is better for instruments like guitar. A
built-in, spring loaded tilt mechanism allows the cabinet to be tilted back to
better direct sound to
your listening position. The cabinet is made of an
acoustically inert, high durability, injection molded polymer material which
dramatically reduces the weight of the cabinet. Each unit comes with a fitted
slip cover and shoulder strap. Both padded and hard shell cases are available
as accessories.
While our combos and speakers are designed to play loudly--and clearly--
enough so that you can be heard in most gigging situations, they are not suited
to playing at extreme volumes. Generating high SPLs may require an
extension cabinet like the Contra EX or augmentation by a larger house
system.
a three-band EQ,
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Power
Preamp
Plug the detachable AC power cord into the receptacle on the back of the amp
and into a wall receptacle. A power switch next to the AC connector turns on
power to the pre- and power amps, illuminating a “power on” indicator on the
front panel of the amp. A 6.3-amp fast blow fuse is mounted on the back panel.
To replace the fuse, turn off the amp, remove the AC cord and use a small
screwdriver to remove the fuse from the fuse holder. A spare fuse is included
with this manual.
All combos will work with either 115 volt, 60 Hz AC or 230 volt, 50 Hz AC power.
A switch located on the rear panel selects the appropriate voltage. Note that
the correct AC power cord must be used for connection to the appropriate wall
plug. If you do not have the right cord, you can buy one from an electronics or
computer store. Be sure the switch is in the correct position for the intended
application.
Please note that units sold in Japan operate at 100 volts only. The above
mentioned voltage switch is not available for these units.
The Contra, Coda R and Corus use combo jacks for the input to each channel
of their preamp. Either an XLR or 1/4 inch connector can be plugged into this
type of jack. The 1/4 inch input has a 1 megohm input impedance that is
optimized to get the best sound from piezo pickups. The XLR input is a low
impedance balanced input with sufficient gain to allow microphones to be
plugged into it. Phantom power is available through the connector for powering
a mic or outboard preamp and can be activated using the push button switch
located next to the connector. To avoid an audible “pop”, set the mic input level
control all the way off when switching on the phantom power. An LED indicates
when phantom power is on. The two channels of the Coda R and Corus
combos can blended to mix two instruments, 2 microphones or a mic and an
instrument thereby performing much like a small PA system.
Operation at 230 volts with the switch in the 115 volt position
will damage the unit.
Operation of a 100
volt amp at any other voltage than 100 volts will damage the unit.
Inputs
Refer to the signal flow diagram and the control panel drawings for more
information (page 4).
Operation
CAUTION: TO REDUCE THE
RISK OF ELECTRIC SHOCK,
DO NOT REMOVE COVER.
NO USER SERVICEABLE PARTS
INSIDE. REFER SERVICING
TO QUALIFIED PERSONNEL.
C A U T I O N : T O R E D U C E THE RISK OF FIRE, REPLACE
FUSE WITH THE SAME TYPE
6.3A FAST BLOW FUSE
Fuse Power Switch Voltage Switch
115/230V
AC Input
115/230 VAC
50/60 Hz
400 Watts
Speaker Output 4 min W
Tweeter Switch
On
0 I
1 15V
Combo Rear Panel