Starting The Equipment - AMIX SNA 70 Manuel Utilisateur

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A / REGULATION

For SNA70, it exists two types of controls:

Regulation on the global level with weighting choice A, M or without. The involved technology, controls the acoustic pressure,

without alteration of input signal spectral density. In that mode, SNA70 does not modify the signal dynamics, but its average

level. This is part A of the synoptic. Leq setting ranges from 64dB to 127dB.

SNA 70 features for instruction levels, for the global level, associated to 4 functioning types:

- External issues (doors/windows) closed / open.

Day / night hours.

Combination of settings allows the regulator to work automatically according to the 4 following modes :



During daytime period and outside acess opening information is not active , the instruction level is " Leq day 1".



During daytime period and outside acess opening information is active , the instruction level is " Leq day 2".



During nightime period and outside acess opening information is not active, the instruction level is " Leq night 1".



During nightime period and outside acess opening information is active, the instruction level is "Leq night 2".

Parameter "hour day  night"

Parameter "hour night  day" :

Regulation by octave band. It allows to limit bass frequencies which are the more often restricting for neighbourhood.

SNA70 provides control card by octave 63Hz, 125Hz, 250Hz and 500 Hz which are the more nuisance frequencies . We can

add in order cards for bands 1KHz, 2KHz and 4 KHz for specific cases acoustic isolation deficiency . On synoptic, this is part B

Analysis bandwith filters are conform with template norm IEC1260 of sono meters and hold a slope of 36dB by octave.The

setting range of Leq level by octave band is from 64 dB to 127 dB.

The frequency weighting for octave bands is the weighted Z, ie linear frequency response for all frequencies. Previous

selection for weighting M or A is only valid for the global regulation.

This regulation modifies audio signal spectral but allows to take back sound level in octave bands which are not nuisance.

Instruction levels can be obviously configurate differently for each octave band but there is only one contrary to global level

regulation

(same level day / night and the same level closed/open window)

The signal which controls 2 regulations can be :

- the acoustic level computed by sensor (this is mode C)

- the power level measured by left+right audio signal which comes in SNA70 (This is mode L).

SNA70 also allows the mixed mode, ie the regulation in global level by the electrical control signal and the regulation by the

octave band sound pressure level of the sensor (mode L+C).

Importante note:

The mode L for regulation by octave band should only be used if the sensor is placed in the near field of an acoustic speaker

and if the dimensions of the room are quite large. (theatre for example).

In the case of small rooms or atypical architectures, this operation must be avoided and use C mode or L + C. Indeed, the

frequencies of the standing waves in such premises (high enough in the spectrum) are not representative nor correlated with

the electrical signal that goes to SNA70. Only the acoustic measurement allows control and effective regulation

Line mode is often used to not be dependent on public noises that sound is in the medium and thus can not affect the

measurement of low-frequency filters such as 63, the 125 or the 250. More filters are very selective and have a slope of 36dB

per octave.

You must choose mode C functioning. Some critical point, regulation level is weak and public noise is

important, you can choose L mode because SNA70 records permantly the acoustic level.

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