Acoustic Image Series II - Manual (Page 5)

Notch/High Pass Filter
The notch/high pass filter is a fixed amplitude, variable frequency type that
inserts either an 18 dB cut or a 12 dB per octave rolloff at frequencies between
30 and 700 Hz , depending on the position of the control. The notch filter is used
to remove a given feedback frequency to reduce feeback “howl”. The high
pass filter is used to reduce the bass output in cases where room location or
instrument/pickup combination results in “boomy” sound. To use either, push
the on/off switch to turn on the filter circuit then select the filter type using the
notch/high pass switch. Start with the control fully counterclockwise and
gradually turn it clockwise until the desired effect is achieved, then experiment
with the position of the control to give you the sound you like best. The Clarus
SL’s do not have the filter capability.
Effects Loop
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 Clarus SL’s do not have the effects level control.
Direct Out
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 two-channel amps, the Direct Out
signal is the combined output of the mic and instrument channels and it is
affected by the input level and tone controls of each channel (post EQ). Any
reverb signal selected is also present in the direct out signal.
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. The Clarus SL’s do not have the ground lift switch.
Reverb (Clarus/Focus 1R, Clarus/Focus 2R and Clarus SL·R only)
Our high-quality digital reverb units offer 8 program selections: 2 “Hall”
(Concert Hall and Arena), 3 “Room” (Club, Chamber and Garage), 2 “Plate”
reverb simulations (Plate and Vocal), and 1 “Spring” reverb simulation. The
Clarus SL·R offers 3 program selections, Concert Hall, Club and Spring. With
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the Clarus/Focus 2R, there are also switches to select which channel (mic or
instrument) has reverb added. If both switches are closed, the selected reverb
setting 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
reverb. You should experiment with both the reverb program selection and the
level control to find the sound that you prefer. When reverb is not used, the
switches for both channels should be off and the level control should be turned
fully counterclockwise.
Power Amp
Speakers are connected to the amps 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 a speaker are
similarly wired. Cables with Speakon connectors are available from Acoustic
Image if you are unable obtain them from your local music store. One Speakon
to 1/4 inch cable is supplied with the unit.
The power amplifier is capable of driving speaker loads as low as 2 ohms (4
ohms for the Focus amps). 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 one of the
speaker jacks, the output signal will be interrupted until the short is removed.
If there is an intermittent short, the output will be interrupted for about one
second each time the short appears. However, the nature of a switching
amplifier makes it difficult to protect against shorts in all circumstances. To
be on the safe side, you should shut off the power to the amp before
connecting or disconnecting speakers from the unit.
We highly recommend the use of Speakon connectors at both the amp and
speaker ends of the connecting cable. If you use these connectors, you will
get the highest possible performance and reliability from your amp. Conversion
of your speaker to Speakon connectors is a simple job. Contact your local repair
shop or Acoustic Image for more information.
All Acoustic Image amps can be operated without a speaker load if required.
When operating without a speaker attached, turn the master level
to zero (all the way counter clockwise). This will prevent the power
amp section of the amp from being driven and protect it from
damage.
Amp Placement
The small size and light weight of the amps allow them to be placed almost
anywhere that is convenient for the preformer. The best results will be
achieved from the speaker/amp combination if the resistance of the speaker
cable is kept as low as possible. That means that a shorter cable is better.
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