5. OPERATION AND USAGE MANUAL
5.1. Start-up
To switch the mixer on push the switch labelled POWER (57) located in the rear panel. After a short time, the
POWER LED below the VU-Meters will light up. Although the switching noise produced by the NUO4 is very low
and almost inexistent when starting up the NUO4 with the main faders down, we highly recommend the "safe
power-up sequence", which means that you should switch on your audio devices in the following order:
1. Sound sources.
2. Mixer, equalizers, active filters.
3. Finally, power amplifiers.
Powering off should be done by following the exact reverse sequence in order to avoid any possible damage to the
loudspeakers.
5.2. Control Description
5.2.1. Input selector
Each channel features an input toggle switch selector (2).
5.2.2. Channel gain
All NUO4 inputs have an accessible input GAIN/sensitivity control (1) to compensate existing level differences
between connected sound sources and the console before mixing. The gain settings must be made with extreme
care using SP (Signal Present) (3) and PEAK (2) LEDs, Vu-Meter and/or phones monitoring as a reference. The
standard reference level to mix audio signals is 0dBV. In order to obtain an optimal mixing, set the input level as
close as possible from 0dBV on the PFL Vu-Meter and make sure to never reach the clipping level, using red
PEAK LEDs as a warning for each channel.
5.2.3. Equalization
The rotary tone controls for each channels provide a +10/-30dB boost/cut range for the bass (7) and treble (5)
bands, and +10/-25dB at the mid range (6). This great attenuation range is specially designed for creative live
performance. Also the bass frequencies can be "killed on the fly" activating the BASS OFF switch (8) located below
each BASS rotary knob.
ATTENTION: Use equalization carefully, by boosting too much the low frequency range, you can induce an
excessive displacement of the speakers membrane.
5.2.4. Monitoring System
The NUO4 is equipped with a flexible and easy monitoring system that will allow the performers to finely tune PFL
(Pre-fader listening) and Mix levels of each input through the VU-METER and the HEADPHONES.
Each channel can be monitorized visually and pre-listened pressing the dedicated yellow led PFL (9) button.
For HEADPHONES monitoring, the PFL/MIX rotary potentiometer (23) allows you to blend a selected PFL together
with the main MIX Program. The VOL rotary potentiometer (22) controls the level of headphones output.
The NUO4 can display (28) at the same time PFL R+L signal (on the first left VU-METER bar) together with the
Main MIX Right and Left signals (second and third VU-METER bars).
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