Australian Monitor ACM250P User Manual

ACM250P

250w Power Amplifier

Operating Manual

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ACM250P, 250 Watt Power Amplifier

Product Description

The ACM250P power amplifier is designed for commercial installations. It can be used for either low impedance (4 ohm)
or 70v/100v line speaker systems. It operates on 230/240 V AC, 50Hz (or 1 15 VAC, 60Hz with factory modification) and
may be desk or rack mounted. The ACM250P features a line level input (with parallel output) and is normally used with
mixers, mixer amplifiers or other power amplifiers. The ACM250P delivers 250 watts into a load of 4 ohms, 70 or 100 volt
line.

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POWER

Front Panel Features

Power Switch

The black rocker switch on the right hand side of the front panel is used to switch the amplifier on and off. The ‘up’
position is on. When the amplifier is connected to an appropriate AC power source and is switched on, the blue power
LED will illuminate.

On LED

The blue “On” LED above the power switch will illuminate when the amplifier is connected to mains power and is
switched on.

Signal LED

The green “Signal” LED located next to the On LED indicates that the ACM250P is receiving audio signal via its line
level input. The signal LED is a simple method to trouble-shoot installations especially in multi amplifier projects.
At a glance the signal LED will indicate that audio is reaching the amplifier.

Protect LED

A feature of the ACM250P is high temperature protection. In most applications, the internal cooling fan will most
probably never switch on. When used with demanding speaker loads or in difficult operating environments, the fan may
regularly switch on to cool the amp down and then switch off again. This switching on and switching off is quite normal.
The “Protect” function is there to protect the amplifier from a high temperature problems which would only occur if the
fan stopped working or became clogged up. In this very rare occurance, the protect LED will illuminate and the amplifier
may shut down. The amplifier will automatically restart once it’s internal temperature has fallen within “safe” limits. If the
protect LED illuminates, it is best to switch the amplifier off, let it cool down and then try it again. If the protect LED
illuminates again, please contact the company who supplied or installed the equipment.

Rack Mounting

The ACM250P is supplied with rack ears attached to allow mounting within a standard 19” equipment rack. As is the
case with almost all audio products, adequate ventilation and air flow is required. When installing multiple ACM250P
power amplifiers within the one rack, it is recommended that at least one rack unit of ventilation space is left between
every two amplifiers.

For table or shelf mounting, the rack ears can be removed using a screwdriver. Once the rack ears are removed, please
reinstall the screws.

DC FUSE

10 A SB

GAIN

INPUT

XLR
1 = Ground
2 = + Signal
3 = - Signal

ENGINEE R ED BY AUDIO TELEX COMM UNICATI ON S PTY LTD SYDNEY AUSTRALIA

Rear Panel Features

AC Power Inlet

The 3 pin IEC power inlet is located on the bottom left of the rear panel and accepts a standard mains power lead fitted
with an IEC connector. Before plugging in a power lead, please check the rear panel of the amplifier to ensure that the
voltage label shows the correct AC operating voltage for your part of the world.

The inlet is equipped with an in-built AC fuse holder fitted with a 6 Amp slow blow fuse plus a spare fuse. Please
ensure that the mains power cord is disconnected before attempting to check or replace this fuse. Power consump­tion is 400 V A (max).

Speaker Output Terminal Strip

Located on the top left of the rear panel is the speaker output terminal strip. Reading from left to right, the connec­tions are:

COM Common or “-” for low impedance speaker loads (4 ohms).
4 The “+” for 4 ohm speaker loads (use with common)

COM Common or “-” for 70v or 100v speaker loads (maximum load of 40 ohms at 100v)
70 The “+” for 70v line speaker loads (use with common)
100 The “+” for 100v line speaker loads (use with common)

Please ensure that the correct “Common” is used. Low impedance and 70/100v loads can be used simultaneously
but please pay careful attention to the overall speaker load. When used individually, the low impedance load should
be 4 ohms or higher while the 100v line load should not fall below 40 ohms. When both outputs are used
simultanously, ensure that neither output is loaded to maximum.

Level Control

Located to the left of the XLR input/output is a recessed screwdriver adjustable level control. The level control is
an input attenuation control normally used to match the amplifier to a wide variety of input signals. In essence, the
amplifier is designed to receive a 700mv input signal however the level control can be used to increase the level for
lower signals or decrease the level for higher input signals. In normal use, the level control is used as a ‘set and
forget’ master level control for the amplifier.

XLR Audio Input and Parallel Output

The ACM250P includes both male and female 3 pin XLR connectors. While the female is normally used as the input
to the amplifier, both XLR’s are connected in parallel so either will work. When signal is connected to one XLR, the
other XLR becomes a line level output allowing the input signal to be distributed (split) to other amplifiers. In some
projects, the same input may be looped through to multiple amplifiers using this method. Up to 6 amplifiers can be
looped together without any noticeable loss in level. A distribution amplifier should be used when more than 6
amplifiers need to be looped.

The XLR’s are wired as follows: Pin 1: Shield. Pin 2: Hot, +, Positive. Pin 3: Cold, -, Negative

Fuse Sizes

Mains 240 VAC - 6 Amperes Slow Blow
DC - 2 x 10 Amperes Slow Blow

Important Safety Information

1. Save the carton and packing material even if the equip­ment has arrived in good condition. Should you ever

need to ship the unit, use only the original factory pack­ing.

2. Read all documentation before operating your equip-
ment. Retain all documentation for future reference.

3. Follow all instructions printed on unit chassis for
proper operation.

4. Do not spill water or other liquids into or on the unit,
or operate the unit while standing in liquid.

5. Make sure power outlets conform to the power re-
quirements listed on the back of the unit.

6. Do not use the unit if the electrical power cord is
frayed or broken. The power supply cords should be
routed so that they are not likely to be walked on or
pinched by items placed upon or against them, paying
particular attention to cords and plugs, convenience re­ceptacles, and the point where they exit from the
appliance.

7. Always operate the unit with the AC ground wire
connected to the electrical system ground. Precautions
should be taken so that the means of grounding of a
piece of equipment is not defeated.

8. Mains voltage must be correct and the same as that
printed on the rear of the unit. Damage caused by
connection to improper AC voltage is not covered by
any warranty .

9. Have gain controls on amplifiers turned down during
power-up to prevent speaker damage if there are high
signal levels at the inputs.

10. Power down & disconnect units from mains voltage

before making connections.

11. Never hold a power switch in the “ON” position if it
won’t stay there itself!

12. Do not use the unit near stoves, heat registers, ra­diators, or other heat producing devices.

13. Do not block fan intake or exhaust ports. Do not
operate equipment on a surface or in an environment
which may impede the normal flow of air around the
unit, such as a bed, rug, weathersheet, carpet, or com­pletely enclosed rack. If the unit is used in an extremely
dusty or smoky environment, the unit should be peri­odically “blown free” of foreign matter.

14. Do not remove the cover. Removing the cover will
expose you to potentially dangerous voltages. There
are no user serviceable parts inside.

15. Do not drive the inputs with a signal level greater

than that required to drive equipment to full output.

16. Do not connect the inputs / outputs of amplifiers
or consoles to any other voltage source, such as a

battery, mains source, or power supply, regardless of
whether the amplifier or console is turned on or off.

17. Do not run the output of any amplifier channel

back into another channel’s input. Do not parallel- or
series-connect an amplifier output with any other
amplifier output.

Audio Telex Communications Pty Ltd is not respon­sible for damage to loudspeakers for any reason.

18. Do not ground any red (“hot”) terminal. Never
connect a “hot” (red) output to ground or to another
“hot” (red) output!

19. Non-use periods. The power cord of equipment
should be unplugged from the outlet when left un­used for a long period of time.

20. Service Information Equipment should be serviced
by qualified service personnel when:

A. The power supply cord or the plug has been
damaged.
B. Objects have fallen, or liquid has been spilled into
the equipment

C. The equipment has been exposed to rain
D. The equipment does not appear to operate normally ,

or exhibits a marked change in performance
E. The equipment has been dropped, or the enclosure
damaged.

Engineered by Audio T elex Communications Pty Ltd, Sydney , Australia

A.B.N. 78 001 345 482 Inc in NSW

www.audiotelex.com.au

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149 Beaconsfield Street, Silverwater NSW 2128

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