APU750 Guide 2012
User Guide
V1.0 Sep’ 2012
2-Way Crossover
Protection Unit for
AIW750E Loudspeaker
The APU750 has been designed to work exclusively with your AIW750E loudspeaker. It
performs the vital function of splitting the full range audio signal from your amplifier and
directing the appropriately split signals to the separate HF and LF loudspeaker panels.
The APU750 features adjustable output levels for the HF panel to allow optimum
balance of sound once installed. The APU750 also features a current sensing fuse to
protect the loudspeaker from being over-driven and potentially damaged. If the
APU750 senses excessive drive current from your amplifier, it will automatically reduce
the sound level from the speaker until the amplifier volume is reduced to a safe level.
Ensure that the APU750 is used only with the AIW750E Evolution series loudspeaker.
Failure to do so may result in speaker damage.
NEVER connect more than one AIW750E loudspeaker to an APU750
Be sure that all connections are made in accordance with this guide.
It is not recommended you use amplifiers with power outputs far greater than the peak
power rating of the AIW750E loudspeaker.
Do not intentionally cause the APU750 to go into protection mode by deliberately
over-driving the loudspeaker.
If your APU750 automatically reduces audio volume from the loudspeaker frequently, it
may suggest the amplifier is too powerful or the layer of plaster applied to the AIW750E
is too thick. In either case please consult with your dealer or Amina Technologies Ltd.
Install this product in a cool, dry and clean place - away from direct sunlight, heat
sources, vibration, dust and moisture.
Do not expose this unit to sudden temperature changes or locate it in an environment
with high humidity. This is to prevent condensation forming inside which may cause
damage to the unit and possibly other devices connected to it.
Do not clean this unit with chemical solvents as this may damage the finish. Use a
clean, dry or damp cloth.
APU750: Positioning
The APU750 is designed to be free-standing or permanently fixed to a suitable
structure using the two mounting holes.
The APU750 does not require ventilation and therefore its installation position is not
critical. However, the product should ALWAYS be installed in a dry environment that will
not exceed 35 degrees Centigrade (95 degrees Fahrenheit).
Do not place equipment on top of the APU750.
Where possible, do not position the APU750 adjacent to mains power cables as these
may interfere with the product’s internal circuit components.
APU750: HF Panel adjustable output
The APU750 features internal jumper
switches to allow the installer to adjust
the output level of the HF
(high-frequency) panel relative to the
LF (low-frequency) panel. The factory
supplied setting is “0dB”. Please read
the following if these settings need to be
The APU750 is a low voltage, passive
device, however ALWAYS disconnect it
from all speakers and amplifiers before
adjusting the internal jumpers (ensure
all equipment is turned off at this point).
The HF panel can be adjusted to suit
personal taste or to allow for minor
variations in frequency response as a
result of uneven plaster thickness. Use
of a sound pressure level meter will help
accurately achieve evenly matched
Set the jumpers as follows depending
on the required output level in the
frequency range 500Hz - 20KHz:
No more than one jumper should be used per bank of 3 pins
- set jumper to 0dB
- set jumper to +2dB
- set jumper to -2dB
APU750: HF Panel adjustable output
Inside the APU750
To change the jumpers, the APU750 housing must be opened by carefully unscrewing
the four screws on the underside of the unit. These are located on the base of
the APU750.
The jumpers (0dB, +2dB, -2dB) for each channel are positioned as indicated in the
below diagram:
Ensure that the jumper is fully pushed
down onto the pins.
ONLY remove and replace the housing
fixing screws by hand. Always use the
correct tool and DO NOT overtighten.
It is recommended that the PCB is left
out of the housing when testing jumper
settings so as to avoid repeated
tightening and un-tightening of the
housing fixing screws. Make sure the
PCB is resting on the housing base and
not on a metal surface of any kind.
Diagram shows the jumper setting for
the factory set 0dB position.
APU750: Connecting to your system
APU750 wiring schematic
(one channel shown)
Stereo Amplifier
Red levers on the Springcon® plugs are used for the “+” loudspeaker connections.
Black levers on the Springcon® plugs are used for the “-” loudspeaker connections.
IMPORTANT - ensure that the HF and LF panels are connected to the correct output of
the APU750. Also ensure that the correct polarity is used. Careful labelling of the
speaker cable during speaker installation is recommended.
IMPORTANT - DO NOT operate either the HF or LF panels in isolation as the load
presented to the amplifier could be below 3.2 Ohm.
Springcon® plugs connection
Ensure the cables are securely
clamped when the Springcon® levers
are closed.
Strip cable back
by 6 - 8mm
(1/4” - 5/16”)
To remove the plugs from the
connecting header squeeze the two
clips on either side to release.
WARNING: Always switch your amplifier off whilst connecting /disconnecting speakers
APU750: Specifications
Model Number
190 x 100 x 42mm (71/2 x 4 x 15/8”)
0.6kg (1. 3lbs)
Filter type
2-way crossover, 2nd order type with adjustable mid/treble output level
Fuse protection
Self-resetting, current sensing type
Suitable for use with Amina AIW750E only
Number of channels
Connection type
Input – 1x Springcon® 2 pole connector (supplied) / Output – 1x Springcon®
4 pole connector (supplied)
Repeated tripping of protection fuse may require fuse replacement by
manufacturer to ensure optimal speaker performance
APU750: Dimensions
Contact information
R. Sá de Figueiredo 6 – C
2790-233 Carnaxide
Telef. (+351) 21 417 76 21
Fax. (+351) 21 030 00 31
Web: www.sislite.pt - email: [email protected]
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