Considerations; Starting Up; Equalization; Ground Loops, Background Noise - Ecler eHMA Serie Manual De Instrucciones

6. CONSIDERATIONS

6.1. Starting up

This is directly done via the POWER mains switch , or by supplying power from the external power
supply (eHMA60 and eHMA120). Even is the power-up noise of this unit is minimal, we highly
recommend to power up all equipment in the following order: sound sources, mixing units, equalizer,
processors and finally power amplifiers. The power down sequence is the inverse of the power up one.

6.2. Equalization

The tone controls of the main output provide a ± 15dB gain/attenuation for each of the bands,
and their central operating frequencies are 100Hz and 10kHz.

6.3. Ground loops, background noise

You should always make sure that the signal sources coming to the mixer, 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 shields, when connected to the chassis, must never be linked together. This will avoid
ground loops.
The eHMA was designed to produce the lowest background noise. Independently from the
electronic design, the resulting background noise directly relies on the correct use and installation of the
mixing unit.
Adjust, where appropriate, the gain of each input for an adequate operating level and then adjust
the VOL controls on the front panel to obtain the desired input mix. Finally, adjust the VOL control of the
main mix output to get the relevant output volume for your installation, and also enable the TK switches
for priority inputs (a signal detection on these priority inputs will attenuate the signal of non-priority
inputs).
Important note on mix level adjustment: setting for example a channel VOL control to "2" and the
output VOL control to "10" is not the same as the opposite. In the first case, the signal entering the
mixing amplifier is weak, but even so it contains a background noise, so the signal/noise ratio is low (low
signal). When the output amplifier equally amplifies both parts as a whole, the output has a very high
background noise. In the second case, as the channel VOL control is set to the maximum, the signal
received by the mixing amplifier has a high level and therefore also a high (good) signal/noise ratio, so
when this signal reaches the output VOL control and is amplified, the signal/noise ratio remains better
than in the previous case.

6.4. 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 unit through the holes of the front
panel.
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