Norsonic Nor275, Пользовательская документация

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• Short circuit. If the output current exceeds 35Amp
due to a short circuit of the output stage or a speaker
system with a nominal impedance less than 2 ohm is
connected.
• Over temperature. If the temperature exceeds the
temperature limit, the amplifier is turned off and the
cooling fan is turned on at full speed.
The signal is turned on again as soon as the error
condition is removed.
Please note that the fan is turned on if the tempera-
ture inside the amplifier exceeds 35 ºC and the input
signal exceeds 100mVrms. The amplifier however is
still well suited for reverberation time measurements in
areas of low background noise since the fan is turned
off when the input signal drops below 100mVrms.
Remote on LED
The “remote on” LED indication is normally illuminated. If
the wireless remote on/off control option is added, the out-
put to the speaker can be switched on/off from the small
remote hand switch. The remote on indicator is turned off if
the output is switched off from the remote switch.
Input connector
The input connector is a 3 pin female XLR. The input
stage is balanced in order to remove influence from
external noise such as hum and crosstalk. A BNC to
XLR adaptor is a part of the delivery schedule. It is
recommended to use a XLR cable from the Nor280 to
the external signal, and convert it to a BNC or other
single ended cable system as close to the signal source
as possible. This ensures a minimum influence from
external hum and noise.
Output connector
The output connector is a 4 pole Speakon NL4MP type.
1+ and 2+ are connected together to form the + out-
put, and 1- and 2- are connected together to form the –
output.
Connecting to a speaker
Connect the amplifier to the speaker. Connect the
signal input to the amplifier or select the noise source. Set
the signal attenuator to off. Switch on the amplifier and in-
crease the signal to the desired leve. Precaution should be
taken against hearing loss – wear hearing protectors!
Power output vs input voltage
The input sensitivity when connected to a Norsonic speak-
er is 1.0 Vrms. This give a power output to the speaker
of about 100 Wrms for the Nor275 and 200 Wrms for the
Nor276.
If higher power is required for other speakers than
Norsonic, the input voltage to the amplifier may be
increased. Max. utput power is 500 Wrms/250 Wrms
in 4/8 ohm. This correspons to a input level of appr. 2
Vrms.
0 dB on the input attenuator/noise generator corre-
spons to 1 Vrms.
Warning: The balanced speaker outputs are
both “hot” with a common DC voltage separate
from ground. Shorting one of the terminals to
ground results in an over-current situation.
Caution !
Consult the table on page 15 for
selecting the level of the noise. If your speaker
is not listed, precaution must be taken in order
not to damage the speaker system.
14 User documentation