Operating Instructions
Proper gain staging of other equipment
The total noise performance of your system depends on proper gain control of all the elements. A "noisy mixer" is usually a quiet mixer in a system whose gain structure is incorrect. As a good starting point, set most volume level controls of other equipment at 3/4 or 75% of full. This will decrease the possibility of overload distortion and keep the amount of background noise to a minimum.
Turn down amplifier levels: In particular, don't set the input controls of a power amplifier "wide open" if you have to run the faders of the mixer in the bottom half of the travel (and the meter of the Multimix 12R well below the "0" mark) to keep the system from being too loud or feeding back. It's better to run the mixer at its normal level, and turn down the amplifier's controls for the desired level. By turning the amplifier's own volume controls down, you turn down the residual noise of everything that precedes it in the signal chain, resulting in a quieter, more controllable system.
However, if the mixer output is too loud, and the input stage of the amplifier being used is an active circuit (instead of a passive voltage divider type), it is possible to clip the preamp stage of the amplifier and cause nasty distortion even if the amp level is low. Use good judgment and consult the manual for your amplifier for more information.
Distortion caused by EQ: If a large amount of EQ is used, it may become necessary to decrease either the trim control, or the channel fader, or both. The EQ is capable of adding quite a bit of gain and is a frequent cause of overload distortion problems. The PEAK LEDs monitor the signal after the EQ circuit, both pre and post fader.
Multimix 12R Reference Manual | 29 |