Considerations; Ground Loops, Background Noise; Cleaning - Ecler MAC70v Notice D'emploi

You must be careful when setting up the general output level of the mixer. The "clip"
display of the connected power amplifiers must never remain permanently lit, but do it only
occasionally by following the rhythm of the bass signals that are being played.
The MAC70v mixing unit is factory adjusted at 0dBV/1V, although this output can be
internally modified to +6dBV/2V. See configuration diagram.
The OUT1 output (45-46) is balanced or symmetrical, and the pin-out of the
connector is as follows:
The balanced circuit simulates an output transformer, so if you wish to use OUT1 in
non-balanced mode, you should short circuit the unused pin to ground. Otherwise, the signal
will not have an appropriate level and quality.
The OUT2 output (47) is non-balanced or asymmetrical.
The MAC70v has two recording outputs: REC1 (44), which is pre-talkover (no signals
which activate the talkover are passed to this output, so no attenuation occurs) and REC2 (43),
which is influenced by the talkover.
Finally, a MONO (24) switch that converts an stereo signal into a monophonic one or
sends one side to both channels. This switch affects the outputs OUT1, OUT2, and REC2.

5. CONSIDERATIONS

5.1. Ground loops, background noise

You should always make sure that the signal sources coming to the unit, as well as all
devices connected to its outputs, do not have their grounds interconnected, that is; ground must
never come from two different devices. Should this ever happen, noises could occur and seriously
interfere the sound quality.
Cable shielding, when connected to the chassis, must never be interconnected, so as to
avoid ground loops.
The MAC70v mixer has been designed for the lowest possible background noise.
Independently from the electronic design itself, background noise level will directly depend on the
right installation and use of the mixing unit.
I. e.: setting a channel VOL to "2" and the output to "10" is not the same as the other
way round. In the first case, the signal coming to the mixing amplifier - which has got its own
noise - is low, and so is the signal-to-noise ratio (low signal). When the output amplifier boosts the
whole signal we will get a very high background noise. In the second case - with the channel
fader at maximum - the mixing level is high, and so is the signal-to-noise ratio. When the signal
reaches the VOL OUTPUT and is boosted, it will keep a much better signal-to-noise ratio than in
the preceding case.

5.2. Cleaning

The front panel should not be cleaned with dissolvent or abrasive substances because
silk-printing could be damaged. To clean it, use a soft cloth slightly wet with water and neutral
liquid soap; dry it with a clean cloth. Be careful that water never gets into the amplifier through
the holes of the front panel.
8
Hot or direct signal
Cold or inverted signal
Ground
> Pin 2
> Pin 3
> Pin 1