Harman EPM12, Руководство пользователя

Страница: 22 / 36

22
USING YOUR EPM CONSOLE
The final output from your sound system can only ever be as good as the weakest link in
the chain, and especially important is the quality of the source signal because this is the
starting point of the chain. Just as you need to become familiar with the control functions
of your mixer, so you must recognise the importance of correct choice of inputs,
microphone placement and input channel settings. However, no amount of careful setting
up can take account of the spontaneity and unpredictability of live performance. The
mixer must be set up to provide “spare” control range to compensate for changing
microphone position and the absorption effect of a large audience (different acoustic
characteristics from soundcheck to show).
MICROPHONE PLACEMENT
Careful microphone placement and the choice of a suitable type of microphone for the
job is one of the essentials of successful sound reinforcement. The diagrams on the left
show the different pick-up patterns for the most common types of microphone. Cardioid
microphones are most sensitive to sound coming from in front, and hypercardioid
microphones offer even greater directivity, with a small amount of pickup behind the
microphone. These types are ideal for recording vocalists or instruments, where rejection
of unwanted sounds and elimination of feedback is important. The aim should be to
place the microphone as close as physically possible to the source, to cut out unwanted
surrounding sounds, allow a lower gain setting on the mixer and avoid feedback. Also a
well chosen and well placed microphone should not need any appreciable equalisation.
There are no exact rules - let your ears be the judge. In the end, the position that gives
the desired effect is the correct position!
INITIAL SETUP
Once you have connected up your system (see the sections on connection and wiring
earlier in this manual for guidance) you are ready to set initial positions for the controls
on your mixer.
Set up individual input channel as follows:
•
Connect your sources (microphone, keyboard etc.) to the required inputs.
WARNING: Phantom powered mics should be connected before the +48V is
switched on. Ensure the PA system is OFF when switching phantom power on
or off.
• Set Master faders at 0, input faders at 0, and set power amplifier levels to about
70%.
•
Provide a typical performance level signal and press the PFL button on the first
channel, monitoring the level on the bargraph meters.
•
Adjust the input gain until the meter display is in the amber section, with occasional
peaks to the first red LED at a typical maximum source level. This allows sufficient
headroom to accommodate peaks and establishes the maximum level for normal
operation (but see note below).
•
Repeat this procedure on other channels as required. As more channels are
added to the mix, the meters may move into the red section. Adjust the overall
level using the Master Faders if necessary.
•
Listen carefully for the characteristic sound of “feedback”. If you cannot achieve
satisfactory input level setting without feedback, check microphone and speaker
placement and repeat the exercise. If feedback persists, it may be necessary to
use a Graphic Equaliser to reduce the system response at particular resonant
frequencies.