Cloud Electronics MA60Media - Manual (Page 19)

MA60 & MA60
media
Installation and User Guide v1.2 19
information regarding the internal jumpers. Care should be taken to ensure that
phantom power is activated only when the microphone connected to the input
requires it – i.e., a capacitor or electret type; other types of microphones (such as
dynamic or ribbon) may be damaged if a DC voltage is applied to them.
Mic gain adjustment
The mic input has a preset gain control
6
adjacent to the input connector. The gain
can be adjusted over a range of 40 dB, from 10 dB to 50 dB. A high overload margin
is maintained at all gain settings. (Note - the gain range is modified if the telephone
matching transformer is in circuit. See “Paging via a telephone system” on page 20
for more details.)
Microphone level control
A front panel level control
3
is provided for the mic input and this provides the user
with a means of adjusting the volume of the microphone. The microphone signal is
unaffected by the music level control
4
. The rear panel gain control
6
should be set
at a level where microphone distortion does not occur even when the front panel
level control is fully clockwise. If the mic level is set too high, the front-panel PEAK
LED
5
will illuminate. Note that this LED also indicates excessive music level.
Paging control
The mic input is equipped with an external access control input; this is a 2-pin
5 mm-pitch screw terminal connector
7
adjacent to the mic input connector. The
access input is primarily intended to provide compatibility with paging microphones
and their associated switching arrangements. By default, mic priority over music is via
AVO mode (Automatic VoiceOver) and the access port is disabled. In AVO mode, the
presence of a signal at the mic input automatically activates the priority circuitry, and
attenuates the current music source by 30 dB so that the announcement is audible.
To use the access port, move internal jumper J5 from its default ‘ON’ setting to
‘OFF’. See “PCB layout diagrams” on page 30 for further information regarding the
internal jumpers. Once enabled, the microphone input is muted as long as the pins of
the access connector are open-circuit. When the pins are connected together, the mic
input becomes active.
In either AVO or SW mode, the music signal is faded back up after the announcement
is complete. Unlike Line 4 priority, the fade-up time (‘release time’) is not adjustable.
If the mic input is being used for a non-announcement purpose (such as karaoke),
mic priority may be disabled by removing J14 altogether. In this setting, the mic input
may be mixed as desired with the music source. (It is recommended that J14 is left
attached to one pin of the header in case a different setting is needed in the future.)