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Overview on the different noise levels
10 dB Heartbeat
80 dB Heavy traffic or telephone ringing
20 - 30 dB Whisper
90 dB Pneumatic drill
40 dB Average home
100 dB Power mower
50 dB Light traffic
120 dB Boom box in car
60 dB Normal conversation
130 dB Pain level
70 dB Vacuum cleaner
140 dB Jet plane 30 meters overhead
It is important to know that doubling the power increases the noise level by 3 dB. The human hearing does
only recognizes a doubling of the sound level when the noise level is increased by 10 dB. Damaging the
hearing does not depend on the sound level but on the noise level and starts way before the pain level.
Many people deceive themselves by thinking that noise is something they can get accustomed to. It is
possible that a positive opinion of a certain noise can reduce the physiological reaction, but the slow impacts
on the inner hearing must not be neglected: over stimulation and continuous elimination of the Cortic organ's
hair cells.
The reason why some people have got accustomed to a certain noise level and are no longer disturbed is
that they have already suffered a hearing damage. This damage make the insensitive to those frequencies
forming the loudest part of the noise. Getting accustomed to noise does not mean anything other than trying
to get along with the hearing loss in everyday life. The hearing loss itself cannot be healed, it can only be
compensated by hearing aids.
Subjectively, the hearing loss feels like dampened ears. This effect weakens with the time, but a loss in
hearing sensitivity often remains.
In order to relax the hearing sufficiently, the noise level should not exceed 70 dB(A) for 10 hours. Higher
noise levels during this relaxing period can prevent the relaxation and promote a permanent hearing damage
(Tinitus) or hearing loss.
Therefore:
Whoever wants to maintain his hearing should use hearing protectors!
4 OPERATING DETERMINATIONS
The stereo PA amplifiers of the SMA series with integrated limiter and bass boost have been specially
designed for stage and the disco applications. The amplifiers may be used in stereo operation, parallel
operation or in mono bridge operation. Thanks to their switch mode power supply unit, the weight of the
amplifiers is considerably lower than that of amplifiers of comparable power equipped with a standard power
supply unit which makes them particularly attractive for rental companies. The amplifiers and the speakers
connected are protected through extensive protective circuits.
This product is allowed to be operated with an alternating current of 230 V, 50 Hz and was designed for
indoor use only.
This device is designed for mobile use and for permanent installations.
By operating amplifying systems, you can produce excessive sound pressure levels that may lead to
permanent hearing loss. Please refer to the explanations under "Legal instructions".
Please note:
operating an amplification system in public or industrial areas, a series of safety instructions
have to be followed that this manual can only give in part. The operator must therefore inform himself on the
current safety instructions and consider them.
Do not shake the device. Avoid brute force when installing or operating the device.
When choosing the installation-spot, please make sure that the device is not exposed to extreme heat,
moisture or dust. There should not be any cables lying around. You endanger your own and the safety of
others!
This device must never be operated or stockpiled in surroundings where splash water, rain, moisture or fog
may harm the device. Moisture or very high humidity can reduce the insulation and lead to mortal electrical
