Input Signal Connections - Rotel Rb-991 Bedienungsanleitung

ROTEL
YourRB-991 is configuredat the factory for the properAC line
voltage in the country where you purchased it (either 115volts AC
or 230voltsACwith a linefrequency of either 50Hzor 60Hz).The
AC line configuration is noted on a decal on the back panel.
Note: Should you move your RB-991 amplifier to another country,
it is possibleto reconfigure your amplifier for use on a different
line voltage. Do not attempt to perform this conversion yourself.
Opening the enclosure of the RB-991 exposes you to dangerous
voltages.Consulta qualifiedservice person or the Rote/factory
service department for information.
If you are goingto be away from homefor an extendedperiod of
time such as a month-long vacation, it is a sensible precaution to
unplugyour amplifier(aswell as other audio andvideo compo-
nents) while you are away.
O and Power Indicator
Power Switch
The power switch is located in the center of the front panel of
your amplifier. Toturn the amplifier on, push the switch in. The
LEDindicator above the switch will light, indicating that the ampli-
fier is turned on. To turn the amplifier off, push the button again
and return it to the out position.
Protection Circuitry
The RB-991features a thermal protection circuit that protects the
amplifier against potential damage in the event of extreme or
faulty operating conditions. Unlike many designs, the RB-991's
protection circuit is independent of the audio signal and has no
impact on sonic performance. Instead, the protection circuit
monitors the temperature of the output devices and shuts down
the amplifier if temperatures exceed safe limits.
Most likely,you will neverseethis protectioncircuitry in action.
However, should a faulty condition arise, the amplifier will stop
playing and the LEDindicator on the front panel will light up.
If this happens, turn the amplifier off, let it cool down for several
minutes, and attempt to identify and correct the problem that
causedthe protection circuitry to engage.When youturn the am-
plifier back on, the protection circuit will automatically reset and
the indicator LEDshould go out.
In most cases,the protection circuitry activates becauseof a fault
condition such as shorted speaker wires, or inadequate ventila-
tion leading to an overheating condition. In very rare cases, highly
reactive or extremely low impedance speaker loads could cause
the protection circuit to engage.
If the protection circuitry triggers repeatedly and you are unable
to isolate and correct the faulty condition, contact your Rotel au-
dio retailer for assistance in troubleshooting.
2

Input Signal Connections

TheRB-991 givesyou a choice of two different kinds of input con-
nections — conventional unbalanced RCAtype connections (such
asfound on nearlyall audioequipment)or balancedXLR-type
connections for use with some high-end preamps or digital pro-
cessors featuring this lower noise connection.
Input Selector Switch
A slide switch in the middle of the RB-991'srear panel selects
which type of input signal to use.The operationof this switch is
self-evident. Put the switch in the unbalanced position when you
are usingthe RCA-type inputs. Putthe switch in the balancedpo-
sition when using XLR-type balanced connections.
Note: Topreventloud noises that neither younor your speakers
will appreciate, makesure the amplifieris turned off whenyou
make any signal connections.
RCA Input Connections (unbalanced) O
[See Figure 2 for wiring illustration]
When a component with RCAconnectors — such as a preampli-
fier or surround sound processor — supplies signals to the
RB-991,the RCA-type phono plug inputs should be used.
Select a high quality pair of audio interconnect cables. Connect
the left channeloutput of your preampto the left channel unbal-
anced input on the RB-991.Connect the other cable to the right
channel unbalanced input. Make sure that the input selector
switch is in the unbalanced position.
XLR Input Connections
[See Figure 3 for wiring illustration]
If youare using oneof the few high-endpreamplifiersor proces-
sors with low-noise balanced signal outputs to drive your RB-991 ,
you may choose to use these low-noise XLR-type connections.
Seeyour Rotelaudio retailer for the appropriatecables.
Connect the left channel output of your preamp to the left channel
balanced input on the RB-991.When properly seated, the connec-
tor should click into the connection.
the right channel balanced input. Make sure that the input selec-
tor switch is in the balanced position.
Speakers
Speaker Selection
We recommend using loudspeakers with a nominal impedance of
4 ohms or higher with the RB-991.You should exercise some cau-
tion in drivingmultiple pairs of speakersin parallel configuration,
becausethe effective impedancethe amplifier sees is cut in half.
Forexample,when driving two pair of 8 ohm speakers,the ampli-
(balanced)
Connect the other cable to