Acoustic Energy Acoustic Image Stereo Amplifier - Manual (Page 6)

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Stereo Operation
Note that channel 2 will not be heard through the speaker
system unless the Ch 2 switch is in the depressed or on position. If you
are not hearing channel 2 in the output, check to be sure that the switch is
on.
Effects (Coda R and Corus only)
The two-channel preamp of the Coda R and Corus can be operated in stereo
mode. When it is in the “on” position, the switch labeled “Ch 2” connects the
channel to the internal power amp and speaker. When it is in the “off” position, it
is disconnected from the internal amp but is accessible from the channel 2
send output. By connecting the send output to a satellite power amplifier (such
as our Focus SA),and putting the switch in the off position,
the preamp
operates in stereo mode. Note that channel 2 remains in the direct out signal
even when the switch is in the off position. This is done since stereo operation
is typically a “stage” mode but not a “house” mode (house systems are typically
not stereo).
Our high-quality effects units (which use the Alesis DSP chips) offer 6
program selections: 3 reverb programs (Hall, Room and Plate), a delay, an
ambient chorus and a flanger. There are switches to select which of the two
channels are processed by the effects unit. Either channel can be connected to
the effects unit. If both switches are engaged, the selected program appears in
both channels. A level control affects the level of the reverb signal that is mixed
with the “dry” signal to control the overall effect of the selected program. You
should experiment with both the program selection and the level control to find
the sound that you prefer. When effects are not used, the switches for both
channels should be off and the level control should be turned fully
counterclockwise.
An extension speaker (ideally, the Contra EX) can be connected to the amp to
increase its output level using the jack provided on your amp’s rear panel.
Speakers are connected via Neutrik Speakon connectors (“twist lock” type).
These connectors are used because of their low contact resistance and non-
shorting operation. The output of each Speakon connector is wired to pole “1”.
Make sure the cables you use to connect an external speaker are similarly
wired. Cables with Speakon connectors are available from Acoustic Image if
you are unable obtain them from your local music store.
The power amplifier is capable of driving speaker loads as low as 2 ohms. Use
a high quality speaker system in order to get the maximum performance from
the amp. The Acoustic Image Contra EX is an excellent choice.
The power amp is short circuit protected. If a short is connected to the
extension speaker jack (or if the internal speaker is shorted), the output signal
will be interrupted until the short is removed. If a short is present, you will hear a
ticking sound at 3 to 4 second intervals which indicates that the short circuit
External Speaker Jack
protection is working.
The omnidirectional low frequency output of the Contra, Coda R, Corus or
Contra EX makes speaker placement relatively noncritical. You will easily be
heard all over the bandstand no matter where one or more are located.
However, best results are obtained when the cabinet is placed on the floor.
Putting the unit on a shelf or stand will reduce bass frequencies. There may be
circumstances where this is desirable. Again, feel free to experiment to find the
sound that is best for you.
In some settings, such as a hollow stage or small, “boomy” room, your amp or
enclosure will produce too much bass. One way to cut unwanted bass output
is to use the built in tilt back feature to lift the front of the cabinet, reducing the
coupling to the floor. To do this, pull the stand into its forward position and set
the combo in place on the floor. The stand is spring loaded so when you pick up
the unit, the stand will spring back into its storage position. You may want to use
the tilt stand at all times in order to aim the high frequency output of the speaker
toward your ear so that you can better hear the amp.
An on-off switch for the tweeter is mounted on the back panel of the combo unit.
Try the unit with the tweeter on and off to decide which sounds best to you.
Since the tweeter covers only the last octave of the musical spectrum, you will
find its effect to be subtle, particularly with bass instruments.
So, what’s the difference between the Corus and the Coda R? The Corus uses
a different woofer than the Coda R. It is more efficient and has slightly less bass
response. When coupled with the other speakers in the three-way system and
after the crossover is adjusted for the higher efficiency of the woofer, the result
is still a flat response like the Contra and Coda R but the low frequency 3 dB
point is higher (60 Hz versus 40 Hz) and the overall efficiency of the system is
higher (94 dB versus 90 dB). Thus the Corus is more optimized for non bass
instruments than the other combos. In particular, guitar players will like the
sound of the Corus. The higher efficiency gives it a more “forward” sound that
guitarists prefer. The slightly higher low frequency cut off is not noticeable with
guitar and other instruments.
The Corus combo has a gray front panel and a gray front grill so that it looks a
little different and can be easily distinguished from the other combos.
Acoustic Image combos and cabinets are made from injection molded polymer
materials. A little care will keep yours looking new for years to come. Use a
clean, dry cloth to clean the cabinet and metal parts of the amplifier.
To be on the safe side, you should shut off the power
to the amp before connecting or disconnecting speakers from the unit.
Tilt Mechanism
Speaker Placement (Combos or Contra EX)
Tweeter Switch
Description of the Corus Combo
Care
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