Introduction; Features; Precautions; About This Manual - A SYSTEMS SR703 User Manual

SR703 CONTRACTOR AMPLIFIER

INTRODUCTION

Congratulations on your purchase of the Asystems
SR703 professional contractor power amplifier. The SR
series is a line of power amplifiers specifically designed
for contracting application� The SR703 has independent
channels and is able to drive 200V, 140V, 100V, 70V,
50V or 25V constant voltage lines� Each channel has
its own power transformer (toroidal type) secondary to
provide maximum audio separation (minimum sound
leakage) between two channels, minimizing interaction
that can otherwise occur on amplifiers with a common
power supply�

FEATURES

√ Automatic dual-speed, high efficiency fan cooling
√ Rear panel detented gain controls for security and
resetability
√ Stereo, bridge or parallel operating modes
√ XLR and barrier strip inputs
√ XLR in and outs for multiple amplifier operation &
easy signal pass-through
√ Fully short-circuit, temperature and DC offset
protection
√ Barrier strip connection determines output mode -
25V, 70V, 100V and direct low-impedance outputs
available
√ Toroidal output transformers provide full electrical
isolation and meet worldwide safety agency approval
√ 45Hz subsonic filter prevents speaker transformer
saturation with minimal effect on program material
√ Power-up muting

PRECAUTIONS

1. When first powering up the amp, keep the amplifier
gain controls all the off, in order to block potentially
damaging or annoying sounds caused by defective
cables or hookups� When turning up the gain, do it
gradually, until normal operation is verified� These
precautions are necessary with all high-power
amplifiers, since they have enough power to blow
most speakers in abnormal situations�
2. Check local voltage levels before connecting the AC
plug� Under no circumstances should the grounding
pin of the power cable be defeated�
3. Speaker Output Shock Hazard! The SR703 amps
are capable of producing hazardous output voltages�
To avoid electrical shock, make sure the cover is in
place over the output terminals, and do not touch
any exposed speaker wiring while the amplifier is
operating�
English

ABOUT THIS MANUAL

Please be reminded that a power amplifier is a high-
current, high-power device and should be treated with
care and respect� Please read this manual before
connecting and operating your unit, and file it in a safe
place for future reference�

FRONT PANEL

1. Power Switch
The power ON/OFF switch with an LED indicator�
2. Protect LED Indicators
The SR703 features several types of protection to prevent
damage to the circuitry during turn-on or fault conditions�
If the LEDs light up, this indicates that one of the various
protections is safeguarding the different sections of the
amplifier and in these cases, the power output is normally
switched off until normal operating conditions are restored.
• Loudspeaker protection: the power-on protection relay
prevents damaging thumps to the speakers as the
power comes on� When the amp is switched on, the
protect LED will light for a few seconds, and then go out,
indicating that the relay has closed�
• Thermal protection on the heat sink: If the amp
overheats, thermal shutdown protects the circuitry until
the temperature is reduced to a safe level�
• Short circuit protection: The Protect LED Indicator
will also light up if the speaker terminals are short-
circuited, or the impedance of the load is too low� In
these circumstances, the Protect LED will stay on until
the fault conditions are rectified.
Some protection situations require the amplifier to be
switched off and then back on for normal operating
conditions to be restored�
3. Signal "Status" LED Indicator
Each channel of the SR703 features a signal LED to show
that there is an audio signal at the input to the channel�
The threshold for the indicator is -26dB, which should be
enough to avoid noise triggering the LED�
4. Limit LED Indicator
The SR703 has a built-in limiter on each channel to
prevent clipping� Should the signal reach a level high
enough to cause clipping, the limiter momentarily reduces
the input signal level, just enough to prevent it� The limit
LED lights whenever this occurs�
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