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TURN ON MODE
AUDIO SENSE
CONSTANT
3-30V
AC/DC
TRIGGER
INPUT
INSTALLATION CONSIdERATIONS
Automating the turn-on of your SC12-30 is one of the easiest steps when installing
it in a distributed system. However, do not plug the main power cord into the
switched AC outlet of your preamplifier or receiver. The high power design of the
SC12-30 requires large amounts of current from its AC power source. Additionally, it
is always recommended to activate the system preamplifier/receiver before turning
on your SC12-30 in order to prevent system “turn-on thumps”. In order to address
these important needs, the SC12-30 has three special turn-on modes that let you
turn the amplifier on only when it is needed. These three options are accessed by
the Turn-On Mode selector switch (see Figure 7).
Turn-On Modes
Constant
– The auto turn-on circuitry is off. The
front panel master power switch operates the
amplifier. In is “On”, Out is “Off”.
Audio Sense
– The master switch on the
front panel must be in the “On” position. The
amplifier is off when there is no audio signal
present at any of the audio inputs, but the
sensing circuitry is on. The turn-on sensing
circuitry looks for a signal present at any of the
audio inputs. If it detects a signal, the adjacent
pair of amplifier channels (i.e. channel 1 & 2 , 3
& 4, etc.) assigned to receive the input signals
will turn on. Once the audio signal stops, the
sensing circuit waits two minutes, then turns all
amplifier channels off.
3-24 Volt Ac/Dc Opto-Isolated Voltage Trigger
- The Power switch on the front
panel must be in the “On” position for the voltage trigger to function. When a Trigger
Plug is inserted into the rear panel connector and the sensing circuitry detects a
voltage, the amplifier is turned on. Once the Trigger voltage is turned off, the sensing
circuit instantly turns the amplifier off. The amplifier is off when there is no 3-24V
AC or DC voltage detected at the trigger input. Voltage triggers can be supplied
by SpeakerCraft automated switchers, some video projectors, some surround
sound processors, or something as simple as a 12 volt AC wall adapter plugged
into the switched outlet of your stereo receiver. Linear DC wall adapters are not
recommended; the long discharge time of the DC adapter’s filter capacitor will delay
the turn-off of the amplifier. Trigger sources must be 3-24VAC or DC, 20mA or greater.
Figure 7
ImporTanT!
The FronT Panel
Power SwiTch muST be in
The on (SwiTch in) PoSiTion
For any oF The Three Turn-
on oPTionS To FuncTion
