B-52 US Series Professional Power Amplifiers - Instruction Manual
THE BEAUTY OF POWER
US SERIES AMPLIFIERS
NOTe:
Match the pin designations printed next
to the output connectors on rear panel to ensure
proper connections.
9. CIRCUIT BReAkeR
The circuit breaker protects the amplifier from faults
at the AC supply and serves as protection when the
amplifier fails.
If the circuit breaker trips, cutting AC power
supply to your amplifier, it may indicate a serious
malfunction or failure. Wait for the circuit breaker to
cool before resetting it by simply pressing the reset
knob. If the circuit breaker repeatedly trips, especially
when there is no signal on the inputs or outputs, this
indicates a failure of your amplifier. DISCONNECT
the power cord from the amplifier immediately and
contact an authorized B-52 Service Center.
There are rare instances when the circuit breaker acts
on a constant heavy overload with a very low imped-
ance load connected to amplifier, protecting your
amplifier against such improper usage. In such cases
you need to check and correct your load (loudspeak-
ers) to provide for the proper load impedance,
and/or reduce output signal.
10. AC INPUT
IEC connector for the AC power cable. Connect the
supplied heavy-gauge 3-pin IEC power cable.
NOTe:
Never disconnect the EARTH pin from the
AC connection. It will defeat safety measures
used in your power amplifier and void the
warranty.
US-Series amplifiers feature comprehensive protection
circuitry that protects both the loudspeakers and the
electronics from malfunctioning. The protection is non-
intrusive, sonically transparent and does not affect the
sound unless there are extreme conditions that acti-
vate the protection circuitry.
The PROTECT LEDs on the front panel illuminate when
the protection is active during the power-up sequence,
when thermal protection is activated, or when there is
a malfunction. When the PROTECT LEDs are ON, the
amplifier’s outputs are muted.
INITIAl POWeR-UP:
The protection circuitry will
activate for about two to three seconds from the time
you turn ON the amplifier. The speaker outputs are
muted during this period. If the amplifier is operating
normally, the protection circuitry will deactivate and
the amplifier will switch to operation mode.
NOTe:
It is normal for the PROTECT LED to fade
gradually after the amplifier is turned OFF.
TheRMAl PROTeCTION:
Excessive heat-sink tem-
peratures will engage the thermal protection circuitry
to avoid damage to your amplifier. The speaker
output will mute and the PROTECT LED will illuminate.
Thermal protection only engages on the channel
which has the overheating heatsink, except the US-
1200 where both channels will be muted. The thermal
protection will automatically restore to normal opera-
tion mode automatically once the heatsink tempera-
ture drops to a safe level.
NOTe:
If the thermal protection constantly
activates, check the impedance of your loud-
speakers and the condition of the air filters on
front of the amplifier. The loudspeakers
impedance must not be lower than what is
specified in this manual for 2-channel and
BRIDGE operation. 8 Ohms and 4 Ohms speaker
loads per channel (8 Ohms and 16 Ohms in
BRIDGE mode) should not trigger the thermal
protection circuitry if the air access is not
blocked and the air filters are clean. 2 Ohms
speaker loads per channel (4 Ohms in BRIDGE
mode) can cause the thermal protection circuitry
to activate occasionally. If this occurs, decrease
the signal level and consider reconthe speakers
connections to reduce the load on the amplifier
(for example, do not connect too many speakers
in parallel to the same channel).
NOTe:
Make sure there is adequate air access
PROTECTION
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