The Electro-Voice ® MA-1206 is a 60-watt, twelve-input mixer amplifier designed for commercial sound applications. It features twelve separate input controls which can be used to adjust the level from any of 12 input sources. Figure 1 shows the layout of the front and rear panels.
Input channels 1-10 are designed to either be used as low-Z balance microphone or line level inputs. The combination connector on inputs 1-10 permits use of either XLR or ¼” input connectors. The block diagram shown in Figure 2 outlines the signal flow for the MA-1206. A signal appearing at either input 1 will automatically mute the other channels unless the mute function is defeated via a switch on the rear panel.
Inputs 11 and 12 are for auxiliary line-level sources such as tape or CD players. Mono or stereo signals may be applied to inputs 11 or 12. The left and right components of a stereo signal can be applied to the dual RCA phono jacks of these inputs and mixed together to drive the built- in monaural power amplifier. A rear panel paging input with gain control is provided for the paging output of a telephone system. An audio signal appearing at this input automatically mutes all other inputs. A preamplifier output jack and power amplifier input jack permit the mixed output to be fed to an external signal processor (graphic EQ or compressor), and then returned to the built-in amplifier. The preamp output may be used to drive an additional power amp with its own set of speakers without interrupting the function of the built-in amplifier.
There is also a 24v dc power option to operate the unit off of a 24v emergency power source. The speaker output is available at a barrier strip, which includes terminals for driving low impedance loudspeaker loads, as well as 25, 70.7 or 100 volt distributed systems.
at the paging input, it shall automatically mute other input sources. The paging input shall be equipped with its own gain control. There shall be a master level control. Separate bass and treble equalization controls shall be provided. The mixer amplifier shall meet the following performance criteria: output power shall be 60 watts; total harmonic distortion shall be less than 1% at 1 kHz; frequency response shall be within ±3 dB from 50 Hz to 15 kHz; input impedance shall be 600- ohms (balanced inputs) or 47 kW (unbalanced inputs); nominal load impedance shall be 4-, 8- or 16-ohms for voice- coil-connected loudspeakers, 25, 70.7 or 100-volt nominal transformer windings for the constant-voltage output.
In addition to a preamplifier output/power amplifier input link, there shall also be a line-level balanced XLR output. The mixer amplifier shall operate from either a standard 120 V ac 50/60 Hz or a 24V dc power source , and measure 13.3 cm (5.2 in.) high x 48.0 cm (18.9 in.) wide x 32.0 cm (12.6 in.) deep. The net weight shall be 9.0 kg (19.8 lb). The mixer amplifier shall be the Electro-Voice ® Model MA-1206.
