Ecler eHMA SERIES User Manual

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Ecler eHMA SERIES User Manual Manual pdf 7 page image

76. CONSIDERATIONS6.1. Starting upThis is directly done via the POWER mains switch , or by supplying power from the external powersupply (eHMA60 and eHMA120). Even is the power-up noise of this unit is minimal, we highlyrecommend 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. EqualizationThe 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 noiseYou should always make sure that the signal sources coming to the mixer, as well as all devicesconnected to its outputs, do not have their grounds interconnected, that is; ground must never come fromtwo different devices. Should this ever happen, noises could occur and seriously interfere the soundquality.Cable shields, when connected to the chassis, must never be linked together. This will avoidground loops.The eHMA was designed to produce the lowest background noise. Independently from theelectronic design, the resulting background noise directly relies on the correct use and installation of themixing unit.Adjust, where appropriate, the gain of each input for an adequate operating level and then adjustthe VOL controls on the front panel to obtain the desired input mix. Finally, adjust the VOL control of themain mix output to get the relevant output volume for your installation, and also enable the TK switchesfor priority inputs (a signal detection on these priority inputs will attenuate the signal of non-priorityinputs).Important note on mix level adjustment: setting for example a channel VOL control to "2" and theoutput VOL control to "10" is not the same as the opposite. In the first case, the signal entering themixing amplifier is weak, but even so it contains a background noise, so the signal/noise ratio is low (lowsignal). When the output amplifier equally amplifies both parts as a whole, the output has a very highbackground noise. In the second case, as the channel VOL control is set to the maximum, the signalreceived by the mixing amplifier has a high level and therefore also a high (good) signal/noise ratio, sowhen this signal reaches the output VOL control and is amplified, the signal/noise ratio remains betterthan in the previous case.6.4. CleaningThe 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 frontpanel.