Despite the relatively low cost, each of the models in the MA series is well equipped. Facilities include input signal indicators, an output level meter, a graphic equaliser, announcement chime, siren and VCA remote control of volume using just a standard potentiometer. There are also external mute and chime controls.
The level of inputs three to six are controlled by the priority control volume when inputs one and two, or the chime or siren are active. All the inputs are also reduced by an adjustable amount when the 'tel' input is active - an input for connection to a private telephone exchange for paging announcements.
The front panels have six rotary controls to adjust the level of the six inputs, each has an LED to indicate when signal is present at the input. A further rotary control, master volume, sets the overall level. When the remote VCA control is used, the master volume control sets the maximum level which can be produced. An adjacent LED indicates if the amplifier's protection circuits are active due to the amplifier operating abnormally, and also indicates if the external mute control is activated.
Two switches above the input level controls activate the siren and chime facilities. Each has an LED to indicate operation. When the siren is de-selected, the siren reduces in level gradually over 2.5 seconds. Above the master volume control is a row of LEDs which indicate the main output signal relative to the rated power output.
(Jim Evans)
