Acoustic Image + Models - Manual (Page 4)

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frequencies from 30 to 60 Hz, the last half of the rotation affects frequencies
between 70 and 400 Hz. This is done so that there is plenty of control in the critical
low frequency range. The notch filter is used to remove a given feedback frequency
to reduce feedback “howl”. The low cut filter is used to reduce the bass output in
cases where room location or instrument/pickup combination results in “boomy”
sound. Press the on/off switch to turn on the filter circuit then select the filter type
using the notch/cut switch. Start with the control fully counterclockwise and
gradually turn it clockwise until the desired effect is achieved. Experiment with the
p o s i t i o n
o f t h e c o n t r o l t o g i v e y o u t h e s o u n d y o u l i k e b e s t
.
Acoustic Image preamps have output (“Send”) and input (“Return”) capability in
each channel to allow you to use effects boxes. The send output is affected by the
input volume and tone controls and can also be used as a preamp output for driving
other power amplifiers. The Return input can be used to directly connect an external
preamp to the unit’s power amp. The effects level control in each channel controls
the volume of the returned (“wet”) signal relative to the original (“dry”) signal.
Because the effects loop is a parallel type, plugging something into the send output
does not interrupt the signal path. So, a tuner can be plugged into the send output
without affecting the signal going through the amp. When the effects loops are not
used, the level controls should be set at zero.
The return input can also be used as an auxiliary input for connecting other line level
signals such as a CD player.
An XLR jack is provided for a Direct Out connection that allows the system’s output
to be fed to mixing boards of house PA systems or recording studios. As a result, the
instrument amplified by the unit can be recorded or further amplified by the house PA
system. In the Coda+ and Corus+ combos, the Direct Out signal is the combined
output of the two channels. A switch is provided to allow you to select whether the
output from the Direct Out jack is affected by the tone controls (post EQ) or not (pre
EQ).
With the switch in either the pre or post EQ position, the input level control affects the
level of the Direct Out signal, the master level does not. This allows independent
adjustment of the “stage” volume (the volume coming from the combo amp) and the
“house” volume (the volume in the house PA system) when the unit is used as a
stage monitor. Once the level has been set for the house, if more volume is needed
on stage, the master level can be increased. This will increase the stage volume but
not the volume in the house PA.
The phase reverse switch is used to reduce feedback and to control phase
interactions between the two channels. If you are using two pickups or a mic
and a pickup, you will find the phase reverse switch to come in handy. Mic
feedback can be reduced by reversing the phase of the signal. Phase related
interactions between a mic and a pickup or two pickups can be cleared up by
reversing the phase of one of the channels. You should experiment with the
phase reverse switch to see if the effect is one that you like.
Effects Loop
Direct Out
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Signal Flow Diagram (Coda+ and Corus+
2 channel version shown, Contra is ch 1
only with notch/hp filter in place of low cut
and phase reverse and no effects or
headphone amp, Contra output
configuration shown in dashed box)
Contra Control Panel
Level Level Bass Mid Master
Direct Out
Treble
Send
Return
Effects
Loop
Notch Cut
On Off
Freq
Input
Mute
Ground lift
Post
EQ
Off On
Phantom Filter
30
70
800
Power
PRE EQ OUT
BUFFER
INPUT BUFFERS
INPUT BUFFERS
OFF ON
-10 dB MIC
ATTEN
ON OFF
-10 dB MIC
ATTEN
FILTER
OFF
CUT
FILTER
OFF
CUT
180
PHASE INV
OFF
180
PHASE INV
OFF
FILTER (CONTRA)