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, a three-band EQ, 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.
Operation
Power
| | | AC Input | On |
RISK OF ELECTRIC SHOCK, | | |
CAUTION: TO REDUCE | THE | | | |
DO NOT REMOVE COVER. | | 115/230 VAC | |
INSIDE. REFER SERVICING | | |
NO USER SERVICEABLE PARTS | | | Tweeter Switch |
TO QUALIFIED PERSONNEL. | | 50/60 Hz |
| | | |
| I | 0 | 400 Watts | |
6.3A FAST BLOW FUSE | | | 115V | |
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 | | | | |
Fuse | Power Switch | Voltage Switch | Speaker Output 4 min |
| | | 115/230V | |
Combo Rear Panel
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. Operation at 230 volts with the switch in the 115 volt position
will damage the unit.
Please note that units sold in Japan operate at 100 volts only. The above mentioned voltage switch is not available for these units. Operation of a 100
volt amp at any other voltage than 100 volts will damage the unit.
Preamp
Refer to the signal flow diagram and the control panel drawings for more information (page 4).
Inputs
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.
