Australian Monitor. AMIS250 User Manual

Clever Features, Contactor Friendly

AMIS250

250w Mixer Amplifier

Operating Manual

AMIS250, 250 Watt Mixer Amplifier

Product Description

The AMIS250 mixer amplifier is designed for commercial installations. It operates on 115 VAC, 60Hz and
may be desk or rack mounted (rack mount kit supplied). The AMIS250 delivers 250 watts into a load of 4
ohms, 25 or 70 volt line. As standard, the AMIS250 is supplied self standing with rubber feet. It features 6
microphone/line input channels as well as a host of unique features including multiple levels of muting, a
VOX relay output, Transformer Balanced 600 Ohm Telephone input, 24 VDC operation and VCA master
level control make the AMIS250 a very flexible amplifier.

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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. This switch will not switch DC power on or off in DC operation. In DC
operation mode, the amplifier is always on and the blue power LED will always be illuminated.

Protect LED

A feature of the AMIS250 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 115 VAC @ 60 Hz. 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.

The inlet is equipped with an in-built AC fuse holder fitted with an 8 amp fuse plus a spare within the
holder. Power consumption is 550VA.

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

24 Volt DC Power Inlet

The AMIS250 features optional 24VDC power to run off a battery supply if required. This is connected via
the rear terminal strip. The front panel Power Switch will not switch DC power ‘on’ or ‘off’ in DC
operation. In this mode the amplifier is always ‘on’.

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 ohms)

4 Ohms
Spare
Constant Voltage Common (use with 25v or 70v)
25 Volt Line
70 Volt Line
Spare
Tone Generator Common (use with one of the 4 tones listed below)
Pre-Announce Chime
Alert Tone
Bell Chime
Evacuation Tone

Note: The minimum impedance (or maximum load) at 70 Volt line should be no less than 20 Ohms.

Phantom Power

This button enables or disables the 18 volts DC phantom power which is available on all microphone inputs
(XLR’s). The “in” position indicates that phantom power is on for all mics. The “out” position means that
phantom power is switched off for all mics. Phantom power is required for electret condenser microphones
which require DC power to operate. While some of these microphones can operate from an internal battery,
having phantom power available on the amplifier eliminates the need to regularly change batteries in the