Sound Performance Lab 2711 manual Control Elements, Mic Gain, About Leveling

Control Elements Mic Gain, About Leveling

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Mic Gain

With the Mic Gain control you can regulate the preamplification of the microphone signal. It ranges from +14 dB to +72 dB. The input stage can handle input levels of up to 18 dB. The value set with the Mic Gain con- trol defines the output level equally for both Output 1 and Output 2.

When you set the Mic Gain you have to consider the type of micro- phone that you are using (dynamic or condenser microphone) as well as its sensitivity. The sensitivity of a dynamic microphone is at around 2 mV/Pa whereas the sensitivity of a condenser microphone can be up to 20 mV/Pa. The result is a difference in output of 20 dB.

You should also consider the sound pressure level of the sound source, the distance of the microphone to it and the acoustics of the room when you set the preamplification.

About Leveling

Initially you should always ensure to have deactivated the -10 dB but- ton so that the VU meter displays correct values (see “-10 dB” on page 11). Now turn up the Mic Gain control until the VU meter displays max- imum levels between 0 dB and +3 dB. At this level you don’t risk any overdrive when you experience sudden and unexpected peaks in the level of the source. Always remember that the VU meter only shows average values and that a peak level can be much higher (up to +10 dB). If necessary, turn on the PPM mode to see the actual peak levels.

Usually levels of around 0 dB and +3 dB are safe. If, however, you expe- rience very high peaks already at minimum Mic Gain values (i.e. drums, brass instruments), you can activate the PAD function (see “PAD” on page 12). The input level is now reduced so that you can regulate Mic Gain again in a useful range.

If you know in advance that the level will be very consistent you can always turn up Mic Gain. In this case you can activate the -10dB button to have more headroom in the display.

IMPORTANT: To exclude any audible distortion the OVL LED should only light up shortly. It starts illuminating 3 dB before a potential overload, so first illumination does not indicate an overload, but that the limit of leveling is reached. Avoid permanent illumination of the OVL LED to exclude overloads (also refer to “Overload LED” on page 13).

10 RackPack: Preference Mic Pre