Acoustic Image S4Plus - Manual (Page 8)

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Once you have made the jumper selections you want, reinstall the
preamp in the chassis.
Speakers are connected via speakon connectors (“twist lock” type)
located on the rear panel. 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 (and the speakers themselves) are similarly
wired.
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 Coda EX, Corus EX
or Ten2 EX are excellent choices. As mentioned above, the power
amp is short circuit protected. If a short is connected to a speaker jack,
the output signal will be interrupted until the short is removed. Note
that when using a 1/4 inch type speaker plug, there is a momentary
short that occurs when the plug is put into the jack. That short can
cause a problem for the amp.
There may be times when you want to operate the amp without a
speaker connected to it. For example, you may want to record using
the Direct Out and don’t want the output of the amp to be heard
through a speaker. In that case, set the master level to zero. By setting
the master level to zero, the signal to the power amp is turned off and it
is not driven without a speaker load which can damage the amp.
Power Amp
Connecting a Speaker
Use Class 2 wiring for speaker cables.
Operation Without a Speaker Connected
Be
sure to set the master level to zero when a speaker load is not
connected to the amp. Operating the amp with no load and the
master level turned up can damage the amp.
To be on the safe side, you should
shut off the power to the amp before connecting or
disconnecting speakers from the unit.
The amp head component of our combo amps can be removed and
used as a stand-alone amplifier. To remove the head unit, first
disconnect the speaker “pigtail” that connects the speaker cabinet to
the amp, then unscrew the docking screws on the rear panel until they
are loose. Grip the cabinet as shown and use the tips of your fingers to
push the head unit out. The fit is quite snug so some force will be
needed.
Once you have removed the head, you will notice the rubber feet
stored in a compartment on the bottom. Remove the feet and screw
them into the four positions on the bottom of the head. When you want
to put the head back into the cabinet, you will have to remove the feet
and put them back into the storage compartment.
To reinsert the head unit, grip the cabinet as shown and push it in with
your thumbs. Again, the fit is snug so some force will be needed. Once
the head unit is in place, tighten the docking screws to pull the head
tight to the docking plate. Reconnect the speaker cable and the unit is
ready to go.
The omnidirectional low frequency output of our speaker cabinets
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. 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
Docking System
Speaker Placement (Combos or Extension Cabs)
Tilt Mechanism
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Operation--Speaker Cabinets
Removal Insertion