Specifications

AMIS60/120
Product Description
The AMIS60 and AMIS120 mixer amplifiers are designed for commercial installations. Both models
operate on [230/240 VAC, 50Hz] (240V version)/[115VAC, 60Hz] (115V version) or 24 VDC, and may be
desk or rack mounted (rack mount kit supplied fitted). Both amplifiers incorporate a 6 zone 100 volt line
speaker zone selector with “All Call”. The AMIS60 will deliver 60 watts into a load of 8 ohms, 70 volt or
100 volt line. The AMIS120 will deliver 120 watts into a load of 4 or 8 ohms, [70 volt or 100 volt line]
(240V version)/[70 volt or 25 volt line] (115V version). Both Models feature 4 universal mic/line inputs,
and an insert point for additional EQ or feedback exterminator if required. The AMIS60/120 also feature a
dual RCA tape output while a balanced, 700mV XLR output is also provided to feed up to six power
amplifiers. Other standard features include on-board Bell, Pre Announce, Alert & Evac tones, Remote
Master VCA Control & dual stage priority muting. As standard, both models are self standing and come
with rubber feet. They may be stacked to a maximum of four units high. [The 115V version also has a
transformer balanced, 600 ohm telephone input] (115V version).
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 switch is set correctly for your part of the world.
The operating voltage is [230/240 VAC @ 50 Hz] (240V version)/[115 VAC @ 60 Hz] (115V version).
(240V version) [The inlet is equipped with an inbuilt AC fuse holder fitted with a 4 amp fuse (ACM120) or
a 2 amp fuse (ACM60) plus a spare within the holder].
(115V version) [The inlet is equipped with an inbuilt AC fuse holder fitted with an 8 amp fuse (AMIS120)
or a 4 amp fuse (AMIS60) plus a spare within the holder].
Power consumption is approximately 125 VA for the AMIS60 and 250VA for the AMIS120.
24 Volt DC Power Inlet
The AMIS60 & AMIS120 feature 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’.
There is no trickle charge resistor across the diode (one diode of a bridge rectifier).
[230V/240V Slide Switch] (240V version)
The operating voltage of the amplifier is user selectable between 230V and 240V via a slide switch located
on the top left side of the rear panel. This switch should be set to match the AC voltage of your country.
The mains transformer is wound with a 230V winding plus a 10V winding internally connected.
Power Amp
The power amp is a push pull single supply amplifier driving a centre tapped transformer. The amplifier
has an overall gain of approximately x10 and the transformer has a turns ratio of approximately [x7] (240V
version)/[x5] (115V version). The sensitivity of the amp is approximately 2.7V.
A particularly good aspect of this amplifier is the current limiting circuit. The sensing circuit is a standard
rail load line limiting circuit but it is the drive circuit that is important. As transistors V12 & V14 (BC640)
turn on transistor V11 (BC639), it pulls bias current away from the amp through diodes D1 & D4 (BAV21)
and pulls drive away from the op amp IC1 (LM1458) through the diode/resistor pair D2/R12 (BAV21/2k2)
& D3/R23. Individually each topology acts to limit the current in the amp but it is the combination of the
two and the fine tuning of there interaction that produces the characteristic soft limiting without the harsh
crossover distortion. It is not until the amp is in hard clip does the amp produce the high freq crossover