Stand Alone Amplifiers - Nexo PS Série Manuel D'utilisation

P.26
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cover on the front panel (lower right corner).
Earth-Lift configuration can be accessed without removing the safety panel by pushing with a small
screwdriver the earth lift switch through two tiny holes in the safety cover. The upper hole switches to
"Ground on", the lower hole to "Ground off" (earth lifted).
Changing the Voltage configuration or the fuses requires the opening of the safety cover (2 outer
screws). 115/230 V mains configuration is made by pushing a switch (according to the silk screen
painting) through two holes. The main fuses are the same in both configurations (no change is required).
If the event of a main fuse failure both fuses shall be changed. The fuses are 5x20mm type temporized.
Fuse reference: T6.3AH250
Note: Two other fuses are located inside the unit on the PCB. Those fuses should never fail in normal
operation. In the event of a failure do not replace those fuses yourself, as something else could be faulty.
Contact an authorized dealer.
The mains power cable can be located on the front or on the back of the PSAmp. Changing the mains
cable from the front to the back shall be made by an authorized dealer. No other control or connection
exists on the back of the amplifier. At installation nothing else is required than sufficient air flow path on
the back of the PS10Amp.

Stand alone Amplifiers

Recommended Power
NEXO recommends high power amplifiers in all cases, budget constraints being the only reason to select
lower power amplifiers. If a problem occurs on an installation without protection, the use of a lower power
amplifier generating half their rated output power (-3dB) will not prevent possible damage. This is due to
the fact that the RMS power handling of the weakest component in the system is always 6 to 10 dB lower
than the amps' rating
Current Rating
It is very important that the selected amplifier behaves correctly under low load conditions. A speaker
system is reactive by nature, on transient signals like music it will require much higher instantaneous
current than its nominal impedance would indicate (four to ten times more). Amplifiers are usually
specified by their continuous RMS power into resistive loads (which is irrelevant); the only useful
information in that regard is the specification into a 2 ohms load. It is possible to make an amplifier
listening test by loading the amplifier with twice the number of cabinets considered for the application (2
speakers per channel instead of one, 4 instead of 2...) and modulating at high level (onset of clipping). If
the signal does not noticeably deteriorate the amplifier is well adapted (overheating after approximately
ten minutes is normal but thermal protection must not operate too quickly after starting this test).
Gain
It is very important to know the voltage gain of all amplifiers present in your set-up. This will ensure the
correct alignment of your system and may be obligatory (for reliability) in cases where only one
TDcontroller drives several amps. The tolerance should be about ±0,5 dB. In practice this can be difficult
to achieve:
Some amplifier brands have an identical input sensitivity for models of different power ratings (this means
DIFFERENT VOLTAGE GAIN for each model). This problematic practice, inherited from non-
PS SERIES MANUAL REV3 10/10/05
AMPLIFIERS