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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
inhigh fidelityamplification.
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
completeclarity ofsoundreproduction.
This manual provides operating information for your Acoustic Image Contra,
CodaR andCorus comboamp orContraEX extensionspeakercabinet.
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 samesophisticated, sensitive preamplifier. Thefeatures of thepreamp and
thespeaker configurationdefinethe specificcombo model.
The power ampis a high efficiency design that requires no external heat sinks
or cooling fansand is capable of drivingloads as low as 2ohms.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
ofyour amptoverify theAC voltagecapability.
The Contracombo is equipped witha one-channel preamp,the Coda Radds 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 ita somewhatdifferent soundfrom theother combos.The inputchannels
of bothpreamp typesincorporate combo jackinterfaces thatallow eithera 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
createa stereosystem.
All ofour speaker enclosuresincorporate a 10-inch downfiringwoofer, 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 andhard shell cases are available
asaccessories.
While our combos and speakers are designed to play loudly--and clearly--
enough so thatyou can be heard inmost gigging situations, they arenot 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,
2
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
frontpanel ofthe amp. A 6.3-amp fastblow fuseis mountedonthe backpanel.
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. Aspare fuse is included
withthis manual.
All combos willwork with either115 volt, 60 HzAC or 230 volt,50 HzAC power.
A switch located on the rear panel selects the appropriate voltage. Note that
the correctAC power cord must be used for connectionto theappropriate 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 intoit. Phantompower is availablethrough theconnector 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 wayoff when switching on thephantom 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
instrumentthereby performingmuchlike asmall PAsystem.
Operation at 230 volts with the switch in the 115 volt position
will damagetheunit.
Operation of a 100
voltamp atanyother voltagethan 100voltswill damagetheunit.
Inputs
Refer to the signal flow diagram and the control panel drawings for more
information(page 4).
Operation
CAUTION: TOREDUCE THE
RISK OFELECTRIC SHOCK,
DO NOTREMOVE COVER.
NO USER SERVICEABLE PARTS
INSIDE. REFERSERVICING
TO QUALIFIEDPERSONNEL.
CAUTION: TOREDUCE
THE RISK OF FIRE, REPLACE
FUSE WITHTHESAME TYPE
6.3AFAST BLOWFUSE
Fuse
Power Switch
Voltage Switch
115/230V
AC Input
115/230 VAC
50/60 Hz
400 Watts
Speaker Output 4 minW
Tweeter Switch
On
0
I
115V
Combo Rear Panel