NAD S250 - Manual (Page 6)

GB
6
7. SOFT CLIPPING
When an amplifier is driven beyond its specified power output it
normally produces “hard clipping” or distortion of the signal. Such
hard clipping, in addition to sounding unpleasant, can damage the
speakers in the system. The NAD Soft Clipping circuit gently limits
the output waveform, minimizing audible distortion and reducing the
change of speaker damage when the amplifier is overdriven. We
recommend that the Soft Clipping switch on the back panel of the
S250 be left in the ON position when system is being operated at
levels that might exceed the amplifier’s power capacity. The LED on
the front panel indicates if Soft Clipping has been engaged.
FRONT PANEL CONTROLS
1. POWER SWITCH
Press this button to switch the amplifier on or off. The Power LED
located just above the power button and Protection LED will light up.
After a few seconds, the Protection LED will turn off, indicating that
the amplifier is ready for use.
The S250 can also be remotely switched from On to Stand-by and
vice-versa using the 12V-trigger input on the back panel. For the
12V-trigger input to work, the S250 must first be turned on by
means of the Power switch, and the switch must be left in this
position. Using the 12V-trigger source component, switch its 12V-
trigger output to on and off. The S250’s trigger input will now follow
the source component’s 12V-trigger output. Ensure that the Auto
Trigger switch on the back panel is in the ON position and that the
12V-trigger input is connected properly.
NOTE: If no cable is attached to the 12-trigger input socket on the
S250’s back-panel, the Power Switch will operate as normal, even if
the Auto Trigger switch on the back panel is in the ON position.
2. SOFT CLIPPING LIGHTS
When the Soft Clipping circuit of the S250 is activated the indicator
LED’s on the front panel will light.
3. PROTECTION/STAND-BY LED
The Protection LED will light up every time the amplifier is switched
on. After a few seconds it will extinguish and the amplifier is ready
for operation. With the 12V trigger input activated (Auto Trigger
switch on back-panel set to ON position) the Protection LED will also
light up to indicate Stand-by status. In this mode, the Power LED will
be off.
This LED will also come on when one or more of the internal five
amplifiers go into protect mode, but the other amplifiers will
continue to function so it is likely you will still hear sound.
When the amplifier is switched off completely from normal operation
by means of the power switch, the Protection LED will light up and
will fade out in a couple of seconds.
NOTE: If you see the Protection LED light up during use, turn off the
amplifier immediately. Check if all speaker wires are connected
correctly and that none of the wires are damaged, causing a short
circuit. Another cause may be excessive heat build-up inside the
amplifier. Make sure there is adequate ventilation around the
amplifier and that none of its ventilation slots, top or bottom, are
blocked. After the amplifier has cooled down, it will function
normally again.
In case the Protection LED remains on despite the checks mentioned
above, turn the amplifier off and consult your NAD dealer.
NOTE: Looking through the S250’s top-cover you may be able to see
5 LEDs. During normal operation these will light up green. In Stand-
by mode all LEDs will light up red. Whenever one of the channels
goes into protection mode, the corresponding LED will also turn
from green to red. If this occurs, switch the amplifier off immediately
and check as indicated above for correct connection and/or heat
build-up.