Behringer DJ Equipment SX4882 Manual De Usuario

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EURODESK SX4882 User Manual

It is positively undesirable to use screened cable to wire an amp to a speaker. 

Speaker leads should be as thick and short as possible, with XLR or wound 

post terminals.) Line-level signals can usually be run unbalanced over short 

or moderate distances (rack to desk etc.), but NOT from the back of the hall 

to the stage, always provided that there are no earth loops (see section 8.3 

“Looming problems” A loop acts as an aerial, positively inviting electromagnetic 

radiation to flow around the system). Microphone lines, however, are another 

story altogether.
Most microphones generate not volts, but millivolts. Protecting such a low 

level signal requires a more sophisticated solution. Hence, all mic networks run 

along balanced lines. It works like this. The mic diaphragm moves forwards and 

backwards according to the air pressure increases and decreases that constitute 

sound waves. Diaphragm movement generates a corresponding electrical 

signal, which is either positive or negative depending on the direction of travel. 

The +ve and -ve signals are mirror images of each other: if you shorted + and - 

you’d end up with nothing: one would cancel out the other. In fact this cancelling 

effect is what makes the balanced line work. Instead of simply shorting the 

negative line to earth, as would be the case in an unbalanced system (losing half 

the signal, or 6 dB, in the process), the two lines are kept apart until they reach an 

electronic (or transformer) balanced input.
Here something exquisitely simple happens:
You may not know this, but whenever a signal is amplified, its polarity is 

reversed. By inverting the negative side and adding it 1:1 to an unchanged 

positive, a balanced input wastes none of the available signal energy. In doing 

so, it also subtracts all the radiation picked up along the line. Random noise 

is unaffected, but you’ll hear no hum, and much reduced thyristor noise 

(from poorly-screened lighting dimmers). Live, you could not run a rig 

without balanced mic lines, and although in the studio cable runs are shorter, 

the recorded medium’s demand on signal to noise is far greater.
When patching a balanced input/output to an unbalanced one, simply short the 

-ve and screen together at the unbalanced input or output.

Fig. 12.1: A balanced microphone line

 MIC/LINE switch (

) UP, PAD switch (

) UP, 

FLIP switch (

) UP

 MIC/LINE switch DOWN, FLIP switch UP

 FLIP switch DOWN

Set GAIN (

1) 

) and all aux sends (

, 

, 

 and 

) to OFF 

(fully counterclockwise).
EQ switch (

2) 

) UP (off).

LOW CUT switch (

3) 

) ON for microphones, OFF for signals with desired 

low frequency content.
CHANNEL MODE set to PFL (

4) 

 UP).

Channel PFL/SOLO (

5) 

) switch UP (

 off).

Check that main PFL/SOLO LED (

6) 

) is not lit.

Channel PFL/SOLO switch (

7) 

) DOWN (

 and 

 should light).

Make a typical noise, or roll the tape. The -20 dB light should flicker, 

1) 

showing that a signal is present. There should also be some activity at the 

MAIN MIX bargraph meters, indicating the SOLOed level.
For LINE INPUTS: Adjust GAIN control (

2) 

) until transient peaks are 

regularly hitting 0 dB.
For MIC INPUTS: If your meters are reading 0 dB although the GAIN control is 

3) 

completely turned counterclockwise, push the PAD switch (

) to lower 

the input signal by 20 dB before you continue the gain adjustment.
TAPE inputs do not pass through the GAIN pot (

4) 

). This is why it is 

important to match the operating level of the desk (-10 dBV or +4 dBu) to 

that of your machine. If the signal is low (due to incorrect operating level 

setting or too low a level having been recorded to tape), try the -10 dBV 

setting. If too high, try +4 dBu. If neither gives a good level, try patching the 

tape track output into a line input and repeat steps 13.1.1 and 13.1.2.
lf EQ is used, repeat steps 13.1.1 & 13.1.2.

5) 

If an insert is used to patch in a compressor, gate, EQ, etc., use any 

6) 

outboard processor’s BYPASS or EFFECT OFF switch to A/B monitor the effect. 

Adjust the processor’s output level so that effected and bypassed signals 

are level matched.
Channel PFL/SOLO switch (

7) 

) UP. Move onto next channel.

13.2.1  
All board settings should be set to the normal default condition before or after 

every session. Usually faders are set to zero (minus infinity), EQs set flat and 

switched out, trimpots and channel aux sends turned fully anticlockwise etc. 

The natural initial setting for some pots, e.g. master aux sends, is unity gain. 

However, some settings, such as selecting PRE or POST for channel aux sends 

and whether TAPE or MIC/LINE is flipped onto B-channel etc. will depend 

on the operating environment, whether in a MIDI or A/V suite, 24-track 

studio or live venue, or even just on the engineer’s preferred way of working. 

Ultimately, the object of the excercise is:

13.2.2  
Set up the multitrack so that any track in “record ready” condition has its input 

monitored when the tape is stationary. Place all tracks to be recorded into 

“record ready” status (once a recording has been made, these tracks should 

automatically switch to tape playback). Check that the input levels to each 

TRACK are optimized before recording commences.