Acoustic Image S4Plus - Manual (Page 5)

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The speaker emulation filter is a low pass filter that modifies the
preamp output to sound like a single speaker guitar amp. It rolls the
frequency off starting a 4 kHz. If you are a guitar player, you may find
this to be a desirable sound, it will allow you to get a more “classic” jazz
guitar sound.
The Clarus preamp has an output (“Send”) and input (“Return”)
capability in each channel to allow you to use effects boxes. The
effects loop for each channel is located on the rear panel of the unit.
See page 3 for a diagram of the rear panel. 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. 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.
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
preamp output to be fed to mixing boards of house PA systems or
recording studios. As a result, the instrument(s) connected to the unit
can be recorded or further amplified by the house PA system. The
direct out jack is located on the front panel of the Clarus preamp. 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.
A ground lift switch is available to “lift” the ground from the output of the
direct out--reducing noise should a ground loop create hum when the
unit is connected to a mixing board.
If the direct out signal is overdriving the mixing board, switch in the 10
dB pad to reduce the signal output level.
Effects Loop
Direct Out
Mute Switch
If you are not
getting any sound out of the amp, check to make sure that the
mute switch is off.
Preamp Output
Stereo Operation
Effects
A switch is provided to allow you to mute the output of the Clarus
without having to turn the amp off. This will allow you to tune your
instrument on stage without being heard. The amp output and direct
out signals are both muted by the switch. The mute switch is on the
front panel and when it is on, the switch is illuminated.
There are 1/4 inch jacks labeled “Preamp Out” on the rear panel of the
Clarus for accessing the output of the preamp.. When the Clarus
preamp is in mono mode, the top jack, labeled “Ch 1” or “Mono” is the
output to use.
An internal jumper option is available to allow the Clarus preamp to
operate in true stereo mode. The output of channel 2 can be
disconnected from the jack labeled “mono” on the rear panel and
connected to the channel 2 output jack by changing the position of a
jumper on the backside of the preamp control board (see the “Jumper
Options” section for details). When in the true stereo mode, the output
of each channel is independently available from each preamp output
jack.
Note that when in the stereo mode, channel 2 is no longer connected
to the internal power amp, so it will not be heard through a speaker
connected to the Clarus.
The Clarus preamp has a high-quality, 24 bit digital effects processor.
Three variable effects are available: a reverb with variable decay time,
a reverb/delay with variable delay, and a delay with variable delay
time. A four position switch selects the program (Off, Reverb,
Delay/Reverb and Delay). There are illuminated switches to select
which of the two channels is 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 amount of effect that is heard in the signal (the
“wet/dry” mix) and another control affects the rate of the effect (reverb
decay time or delay time). For example, the rate control has enough
range that the Reverb program can be varied from a large hall to a
small room. You should experiment with both the program selection
and the level and rate controls to find the sound that you prefer. When
effects are not used (program switch in the off postion), the switches
for both channels should be off and the level control should be turned
fully counterclockwise.
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