Here’s a PA system used for the sound reinforcement of meetings. Considering the number of participants, four microphones are prepared. A 12-channel MG12XU analog mixer, a PX3 power amplifier, and two CBR12 speakers will be used.
(1) First, place the mixer in a location that will not interfere with the meeting. Place the mixer on a desk or table at an appropriate height where it can be easily operated.
(2) Position the power amplifier and speakers. To prevent acoustic feedback, place the CBR12 speakers at either side of the participants: Don't point the speakers towards the microphones.
(3) Prepare the AC power for the mixer and power amplifier. But do not turn the power on until all the connections have been made.
(4) Connect the mixer and the power amplifier with XLR cables. Connect the power amplifier and the speakers with speaker cables.
1. Connecting the microphones
Connect the four microphones to channels 1 through 4 with XLR cables.
2. Turn the power on
(1) Set the mixer's GAIN, fader, and the volume levels of the power amplifier to minimum.
(2) When turning the power on, first turn the mixer's power on then the amplifier's power, in order to avoid generating any noise . Note: When turning the power off, first turn the power amplifier off and then the mixer.
3. Producing Sound
The example given here is for a single microphone channel.
(1) Adjust the level of the power amplifier. For now, set it to the 12 o'clock position. Note: This is a temporary volume setting for the power amplifier. Readjust the volume later as needed to a suitable level.
(2) Turn on the STEREO channel switch, and raise the fader to "0".
(3) Turn on the channel 1 ON button and the ST button, and raise the fader to "0".
(4) Adjust the GAIN with this setting in order to get the necessary volume. Pay attention and adjust the GAIN so that the PEAK indicator on the fader does not light up.
Once adjustment for one microphone has been completed, adjust the volume for the other microphones in the same way.
4. Turning unused channels off
When one person is talking, any other surrounding microphones will also pick up those sounds. Pulling down the faders will get rid of those sounds; but since we have already taken the time to adjust the volume balance for each channel, it is better to use the channel ON button to switch off unused channels. This will keep the sound clear and intelligible.