Australian Monitor ACM250 User Manual

ACM250

250w Mixer Amplifier

Operating Manual

ACM250, 250 Watt Mixer Amplifier

Product Description

The ACM250 mixer amplifier is designed for commercial installations. It operates on 230/240 V AC, 50Hz (or 1 15 VAC,
60Hz with factory modification) and may be desk or rack mounted (rack mount kit supplied). The ACM250 delivers 250
watts into a load of 4 ohms, 70 or 100 volt line. As standard, the ACM250 is supplied self standing with rubber feet. They
may be stacked to a maximum of four units high.
.

Front Panel Features

Microphone/Line Level Controls

The 6 dual mic/line input controls are labelled Ch 1 through to Ch 6 and should be adjusted to provide the required level
mix for each individual channel. Start with the controls set to level 0 and turn the controls clockwise until the desired mix
level for each channel is reached.

Bass Control

Setting this control in the centre position will give an overall flat bass response. Adjusting the bass control in a
clockwise direction will provide up to 12 dB of bass boost @ 100 Hz. Adjusting the bass control in a counter-clockwise
direction will provide up to -12 dB of bass cut @ 100 Hz.

Middle Control

Setting this control in the centre position will give an overall flat middle response. Adjusting the mid control in a
clockwise direction will provide up to 12 dB of mid boost @ 600 Hz. Adjusting the mid control in a counter-clockwise
direction will provide up to -12 dB of mid cut @ 600 Hz.

Treble Control

Setting this control in the centre position will give an overall flat treble response. Adjusting the treble control in a
clockwise direction will provide up to 9 dB of treble boost @ 10kHz. Adjusting the treble control in a counter-clockwise
direction will provide up to -9 dB of treble cut @ 10 kHz.

Master Output Control

The Master level pot controls the overall output level of the amplifier depending on the levels set for the individual input
channels as detailed above. Start with the control set to level 0 and turn clockwise until the desired output level of the
amplifier is reached.

Power Switch

This switch controls the switching of AC power to the amplifier. A blue On LED will indicate whether the amplifier is
switched on or off.

Protect LED

A feature of the ACM250 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 amplifier will shut down and the protect LED
will illuminate. 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.

Rear Panel Features

AC Power Inlet

The operating voltage is 230/240 V AC @ 50 Hz or 1 15 V AC @ 60 Hz (with factory modification). 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 switch is set
correctly for your part of the world.

The inlet is equipped with an in-built AC fuse holder fitted with a 6 amp fuse plus a spare within the holder. Power
consumption is 400 watts.

---- Please ensure that the mains power cord is disconnected before attempting to check or replace this fuse----

230V/240V Slide Switch

The operating voltage of the amplifier is user selectable between 230V and 240V via a slide switch located on the right
of the AC inlet. This switch should be set to match the AC voltage of your country.

Speaker Output Terminal Strip

The screw terminals on the left hand side of the strip allow access to the direct speaker outputs of the amplifier. The
screw terminals on the right hand side are for activation of the in-built 4 tone generator. Reading from left to right the
terminals are: Low Impedance Common (use with 4 or 8 ohms)

4 Ohms
Spare
Constant V oltage Common (use with 70v or 100v)
70 V olt Line
100 V olt Line
Spare
T one Generator Common (use with one of the 4 tones listed below)
Pre-Announce Chime
Alert T one
Bell Chime
Evacuation T one

Note: The minimum impedance (or maximum load) at 100 Volt line should be no less than 40 Ohms.