Rotel Power Supply RB981 User Guide

RB-981  
STEREO POWER AMPLIFIER  
AMPLIFICATEUR DE PUISSANCE STÉRÉO  
STEREO-ENDSTUFE  
ETAPA DE POTENCIA ESTEREOFONICA  
POWER AMPLIFIER RB-981  
POWER  
PROTECTION  
BRIDGED MONO  
Owner’s Manual  
Guide d’utilisation  
Bedienungsanleitung  
Manual de Instrucciones  
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Figure 1: Controls and Connections / Commandes et branchments  
Bedienelemente und Anschüsse / Controles y Conexiones  
POWER AMPLIFIER RB-981  
POWER  
PROTECTION  
BRIDGED MONO  
1
2
3
4
SPEAKER IMPEDANCE  
STEREO 4 OHMS MINIMUM  
BRIDGED 8 OHMS MINIMUM  
WARNING:TO REDUCE THE RISK OF FIRE  
OR ELECTRICAL SHOCK, DO NOT EXPOSE  
THIS EQUIPMENT TO RAIN OR MOISTURE.  
CAUTION  
RISK OF ELECTRIC SHOCK  
DO NOT OPEN  
POWER AMPLIFIER  
MODEL NO. RB-981  
POWER CONSUMPTION: 400W  
AVIS: RISQUE DE CHOC ELECTRIQUE–NE PAS OUVRIR  
SPEAKERS  
RIGHT  
LEFT  
RIGHT INPUT  
LEFT INPUT  
SERIAL NO.  
5
6
5
7
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STEREO POWER AMPLIFIER RB-981  
Figure 2: Stereo Connections – Inputs and Speakers / [French Translation]  
[German Translation] / [Spanish Translation]  
PREAMPLIFIER / PRÉAMPLIFICATEUR / VORVERSTÄRKER / PREAMPLIFICADOR  
PREAMP OUTPUTS  
L
R
ROTEL RB-981  
WARNING:TO REDUCE THE RISK OF FIRE  
OR ELECTRICAL SHOCK, DO NOT EXPOSE  
THIS EQUIPMENT TO RAIN OR MOISTURE.  
SPEAKER IMPEDANCE  
STEREO  
CAUTION  
4
OHMS MINIMUM  
RISK OF ELECTRIC SHOCK  
DO NOT OPEN  
POWER AMPLIFIER  
MODEL NO. RB-981  
BRIDGED  
8 OHMS MINIMUM  
AVIS: RISQUE DE CHOC ELECTRIQUE–NE PAS OUVRIR  
POWER CONSUMPTION: 400W  
SPEAKERS  
RIGHT  
LEFT  
RIGHT INPUT  
LEFT INPUT  
SERIAL NO.  
Figure 3: Bridged Mono Connections – Inputs and Speakers / [French Translation]  
[German Translation] / [Spanish Translation]  
PREAMPLIFIER / PRÉAMPLIFICATEUR / VORVERSTÄRKER / PREAMPLIFICADOR  
PREAMP OUTPUTS  
L
R
ROTEL RB-981  
WARNING:TO REDUCE THE RISK OF FIRE  
OR ELECTRICAL SHOCK, DO NOT EXPOSE  
THIS EQUIPMENT TO RAIN OR MOISTURE.  
SPEAKER IMPEDANCE  
STEREO  
CAUTION  
4
OHMS MINIMUM  
RISK OF ELECTRIC SHOCK  
DO NOT OPEN  
POWER AMPLIFIER  
MODEL NO. RB-981  
BRIDGED  
8 OHMS MINIMUM  
AVIS: RISQUE DE CHOC ELECTRIQUE–NE PAS OUVRIR  
POWER CONSUMPTION: 400W  
SPEAKERS  
RIGHT  
LEFT  
RIGHT INPUT  
LEFT INPUT  
SERIAL NO.  
JUMPER LOCATIONS / FRENCH TRANSLATION /  
GERMAN TRANSLATION / SPANISH TRANSLATION  
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ENGLISH  
Contents (circled numbers refer to illustration)  
About Rotel  
A family whose passionate interest in music led them to manufac-  
ture high fidelity components of uncompromising quality founded  
Rotel over 30 years ago. Through the years that passion has re-  
mained undiminished and the family goal of providing exceptional  
value for audiophiles and music lovers, regardless of their budget,  
is shared by all Rotel employees.  
About Rotel __________________________________________ 1  
Getting Started ______________________________________ 2  
A Few Precautions  
Placement  
2
2
AC Power and Control ________________________________ 2  
The engineers work as a close team, listening to, and fine tuning  
each new product until it reaches their exacting musical stan-  
dards. They are free to choose components from around the  
world in order to make that product the best they can. You are  
likely to find capacitors from the United Kingdom and Germany,  
semi conductors from Japan or the United States, while toroidal  
power transformers are manufactured in Rotels own factory.  
AC Power Input  
Power Switch  
Protection Circuitry  
7
2
2
2
1
and Power Indicator  
2
3
Input Signal Connection ______________________________ 3  
Input Signal Connection  
5
3
Speaker Connection __________________________________ 3  
Rotel’s reputation for excellence has been earned through hun-  
dreds of good reviews and awards from the most respected re-  
viewers in the industry, who listen to music every day. Their  
comments keep the company true to its goal – the pursuit of  
equipment that is musical, reliable and affordable.  
Speaker Selection  
3
3
3
3
Speaker Wire Selection  
Polarity and Phasing  
Stereo Speaker Connection  
6
Bridged Mode Operation ______________________________ 4  
All of us at Rotel thank you for buying this product and hope it will  
bring you many hours of enjoyment.  
Resetting Jumpers  
4
4
Input Connection  
Bridged Speaker Connection  
4
Troubleshooting ______________________________________ 4  
Front Panel Power Indicator Is Not Lit  
Fuse Replacement  
No Sound  
4
4
4
4
Protection Indicator Is Lit  
Specifications ________________________________________ ?  
1
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STEREO POWER AMPLIFIER RB-981  
Getting Started  
AC Power and Control  
Thank you for purchasing the Rotel RB-981 Stereo Power Ampli-  
fier. When used in a high-quality music or home theater system,  
your Rotel amplifier will provide years of musical enjoyment.  
AC Power Input 7  
Because of its high power rating, the RB-981 can draw consider-  
able current. Therefore, it should be plugged directly into a 2-pin  
polarized wall outlet. Do not use an extension cord. A heavy duty  
multi-tap power outlet strip may be used if it (and the wall outlet)  
is rated to handle the current demanded by the RB-981 and all the  
other components connected to it.  
The RB-981 is a high-power, two-channel power amplifier, provid-  
ing the highest level of audio performance. Discrete output de-  
vices, a massive power supply, premium components, and Rotel’s  
Balanced Design ensure superb sound quality. High current capa-  
bility allows the RB-981 to drive the most demanding loudspeakers.  
Be sure the power switch on the front panel of the RB-981 is  
turned off (in the out position). Then, connect the supplied power  
cord to the AC power outlet.  
Be aware that the RB-981 is capable of high power levels, in ex-  
cess of 130 watts per channel. Make sure that your speakers can  
handle the power of the RB-981. If in doubt about your speakers,  
ask your local Rotel audio retailer for advice.  
Your RB-981 is configured at the factory for the proper AC line  
voltage in the country where you purchased it (either 115 volts AC  
or 230 volts AC with a line frequency of either 50 Hz or 60 Hz). The  
AC line configuration is noted on a decal on the back panel.  
The RB-981 is straightforward in its installation and operation. If  
you have experience with other stereo power amplifiers, you  
shouldn’t find anything perplexing. Plug in a pair of high-quality  
RCA cables from your preamp into the amplifier inputs, wire up  
your speakers, and enjoy.  
Note: Should you move your RB-981 amplifier to another country,  
it is possible to reconfigure your amplifier for use on a different  
line voltage. Do not attempt to perform this conversion yourself.  
Opening the enclosure of the RB-981 exposes you to dangerous  
voltages. Consult a qualified service person or the Rotel factory  
service department for information.  
A Few Precautions  
Please read this manual carefully. In addition to basic installation  
and operating instructions, it provides valuable information on  
various RB-981 system configurations as well as general informa-  
tion that will help you get optimum performance from your system.  
Please contact your authorized Rotel audio retailer for answers to  
any questions you might have. In addition, all of us at Rotel wel-  
come your questions and comments.  
If you are going to be away from home for an extended period of  
time such as a month-long vacation, it is a sensible precaution to  
unplug your amplifier (as well as other audio and video compo-  
nents) while you are away.  
Save the RB-981 shipping carton and all enclosed packing mate-  
rial for future use. Shipping or moving the RB-981 in anything  
other than the original packing material may result in severe dam-  
age to your amplifier.  
Power Switch 1 and Power Indicator 2  
The power switch is located on the front panel of your amplifier.  
To turn the amplifier on, push the switch in. The LED indicator  
above the switch will light, indicating that the amplifier is turned  
on. To turn the amplifier off, push the button again and return it to  
the out position.  
Fill out and send in the owner’s registration card packed with the  
RB-981. Also be sure to keep the original sales receipt. It is your  
best record of the date of purchase, which you will need in the  
event warranty service is ever required.  
Protection Circuitry  
3
The RB-981 features 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-981’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.  
Placement  
Because of its high power output, the RB-981 may generate con-  
siderable heat. The heat sinks and ventilation openings in the am-  
plifier are more than capable of dissipating this heat under normal  
conditions, but don’t smother your amplifier. There must be ad-  
equate clearance around the chassis. The ventilation slots in the  
top cover must be unblocked, and there must be reasonable air-  
flow around the amplifier. Use common sense when placing the  
amplifier in a cabinet or when stacking other equipment.  
Likewise, remember the weight of the amplifier when you select  
an installation location. Make sure that the shelf or cabinet can  
support its considerable bulk. Again, use common sense.  
2
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ENGLISH  
Speaker Wire Selection  
Most likely, you will never see this protection circuitry in action.  
However, should a faulty condition arise, the amplifier will stop  
playing and the LED indicator on the front panel will light up.  
Use insulated two-conductor stranded wire to connect the RB-981  
to the speakers. The size and quality of the wire can have an au-  
dible effect on the performance of the system. Standard speaker  
wire will work, but can result in lower output or diminished bass  
response, particularly over longer distances. In general, heavier  
wire will improve the sound. For best performance, you may want  
to consider special high-quality speaker cables. Your Rotel audio  
retailer can help in the selection of appropriate cables for your  
system.  
If this happens, turn the amplifier off, let it cool down for several  
minutes, and attempt to identify and correct the problem that  
caused the protection circuitry to engage. When you turn the am-  
plifier back on, the protection circuit will automatically reset and  
the indicator LED should go out.  
In most cases, the protection circuitry activates because of 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.  
Polarity and Phasing  
The polarity — the positive/negative orientation of the connec-  
tions — for every speaker and amplifier connection must be con-  
sistent so all the speakers will be in phase. If the polarity of one  
connection is mistakenly reversed, bass output will be very weak  
and stereo imaging degraded. All wire is marked so you can iden-  
tify the two conductors. There may be ribs or a stripe on the insu-  
lation of one conductor. The wire may have clear insulation with  
different color conductors (copper and silver). There may be po-  
larity indications printed on the insulation. Identify the positive  
and negative conductors and be consistent with every speaker  
and amplifier connection.  
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.  
Input Signal Connection  
5
[See Figure 2 for normal stereo wiring illustration.]  
The RB-981 has conventional RCA type input connectors, the type  
found on nearly all audio equipment.  
Stereo Speaker Connection 6  
The RB-981 has two pairs of color coded binding posts on the  
back panel. These connectors accept bare wire, connector lugs,  
or dual banana type connectors (except in the European Commu-  
nity countries where their use is not permitted).  
Note: To prevent loud noises that neither you nor your speakers  
will appreciate, make sure the amplifier is turned off when you  
make any signal connections.  
Route the wire from the RB-981 to the speakers. Give yourself  
enough slack so you can move the components enough to allow  
access to the speaker connectors.  
Select a high quality pair of audio interconnect cables. Connect  
the left channel output of your preamp to the left channel input on  
the RB-981. Connect the right channel output of your preamp to  
the right channel input.  
If you are using dual banana plugs, connect them to the wires and  
then plug into the backs of the binding posts. The hexagonal  
thumbscrews of the binding posts should be screwed in all the  
way (clockwise).  
If you are using terminal lugs, connect them to the wires. If you  
are attaching bare wires directly to the binding posts, separate  
the wire conductors and strip back the insulation from the end of  
each conductor. Be careful not to cut into the wire strands. Un-  
screw (turn counterclockwise) the binding post hexagonal thumb-  
screws. Place the connector lug around the binding post shaft, or  
insert the bundled wire into the hole in the shaft. Turn the hexago-  
nal thumbscrews clockwise to clamp the connector lug or wire  
firmly in place.  
Speaker Connection  
Speaker Selection  
We recommend using loudspeakers with a nominal impedance of  
4 ohms or higher with the RB-981. You should exercise some cau-  
tion in driving multiple pairs of speakers in parallel configuration,  
because the effective impedance the amplifier sees is cut in half.  
For example, when driving two pair of 8 ohm speakers, the ampli-  
fier sees a 4 ohm load. When driving multiple speakers in parallel,  
it is recommended that you select speakers with a nominal imped-  
ance of 8 ohms or higher. Speaker impedance ratings are less  
than precise. In practice, very few loudspeakers will present any  
problems for the RB-981. See your Rotel audio retailer if you have  
any questions.  
Note: Be sure there are no loose wire strands that could touch  
adjacent wires or connectors.  
3
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STEREO POWER AMPLIFIER RB-981  
Bridged Mono Operation  
Troubleshooting  
[See Figure 3 for bridged operation jumper setting and connec-  
tion illustration.]  
Most difficulties in audio systems are the result of poor or wrong  
connections, or improper control settings. If you encounter prob-  
lems, isolate the area of the difficulty, check the control settings,  
determine the cause of the fault and make the necessary  
changes. If you are unable to get sound from the RB-981, refer to  
the suggestions for the following conditions:  
The two channels of the RB-981 can be “bridged”. In this configu-  
ration the single channel produces a massive 390 watts! This fea-  
ture allows you to increase the overall power output of your  
system by bridging the RB-981 and adding a second bridged RB-  
981. Or the RB-981 is bridged to drive a monophonic subwoofer.  
Note however that when the RB-981 is bridged the speaker con-  
nected to it must have an impedance of 8 ohms or more.  
Front Panel Power Indicator Is Not Lit  
No main power to the RB-981. Check the front panel power  
switch. Make sure that it is set to the on position. Check AC power  
connections at the amplifier and the AC outlet.  
In order to use the RB-981 in bridged mode, three “jumper” con-  
nectors inside the amplifier must be moved from one set of pins  
to another. This task should be done by a qualified technicain. See  
your Rotel audio retailer. In addition the RB-981 is connected to  
the other components in a different way. When the RB-981 is  
setup for bridged operation the Bridged Mono indicator light 4  
on the front panel will light.  
Fuse Replacement  
If everything checks out correctly and you still cannot get the am-  
plifier to turn on, the internal power fuse may have blown. If you  
believe this has happened, contact your Rotel dealer for informa-  
tion on where to take your amplifier to get the fuse replaced.  
Resetting Jumpers  
No Sound  
If the amp is getting AC power, but is producing no sound, check  
the Protection indicator on the front panel. If it is lit, see below. If  
not, check all of your connections and control settings on associ-  
ated components.  
Before opening the RB-981 cabinet to reset the jumpers, the  
power cord must be unplugged from the wall. DO NOT OPEN THE  
CABINET OF THE RB-981 BEFORE THE POWER CORD HAS BEEN  
UNPLUGGED FROM THE WALL. FAILURE TO DO SO WILL EXPOSE  
YOU TO HAZARDOUS VOLTAGES.  
Protection Indicator Is Lit  
The front panel indicator lights when the RB-981 protection cir-  
cuits have shut off the amplifier. Typically, this occurs only when  
the ventilation openings are blocked, when there is faulty speaker  
wiring, or after a period of extreme use. Turn off the system and  
wait for the amp to cool. Then push the front panel power switch  
in and out to reset the protection devices. If the problem is not  
corrected or reoccurs, there is a problem with the system or the  
amplifier itself.  
After the power cord has been unplugged, remove the screws  
that hold the cabinet cover in place and slide the cover off the  
amplifier. Locate the three jumper pin blocks labeled S 601, S 602  
and S 603. The factory standard (stereo) position of the jumpers is  
on pins 1 and 2 of each block. There is a * mark on the circuit  
board next to this position. To convert the RB-981 to bridged mono  
move all three jumpers so they are on pins 2 and 3 of each jumper  
pin block. Replace the cover of the cabinet. Do not plug the RB-  
981 power cord back into the wall outlet until the cabinet cover  
has been replaced.  
Input Connection  
When using the RB-981 in bridged mono mode, connect the cable  
from the preamplifier output to the left input. No connection is  
made to the right input.  
Bridged Speaker Connection  
When using the RB-981 in bridged mono mode, the wire to the  
speakers is connected to the positve terminals of the left and right  
channels. Connect the wire that goes to the postive terminal of  
the speaker to the positve terminal of the left channel of the RB-  
981. Connect the wire that goes to the negative terminal of the  
speaker to the positve terminal of the right channel of the RB-981.  
No connections are made to the negative terminals of the RB-981.  
4
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5
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STEREO POWER AMPLIFIER RB-981  
Specifications  
Technische Daten  
Continuous Power Output  
(20-20 kHz, < 0.03%, 8 ohms)  
130 watts/ch  
Dauerausgangsleistung  
(20-20 kHz, < 0,03%, 8 Ohm)  
130 Watt pro Kanal  
< 0,03 %  
Total Harmonic Distortion (20Hz-20kHz, 8 ohms) < 0.03%  
Gesamtklirrfaktor (20 - 20.000 Hz, 8 Ohm)  
Intermodulation Distortion (60 Hz : 7 kHz, 4:1)  
Frequency Response ( +0.5, -3dB dB)  
Damping Factor (20-20,000 Hz, 8 ohms)  
Speaker Impedance (Normal mode)  
Signal to Noise Ratio (IHF A network)  
Input Impedance/Sensitivity  
< 0.03%  
Intermodulationsverzerrung (60 Hz : 7 kHz, 4:1) < 0,03 %  
4Hz-100kHz  
1000  
Frequenzgang ( +0.5, -3dB dB)  
Dämpfungfaktor (20-20,000 Hz, 8 Ohm)  
Lautsprecherimpedanz (Normalbetrieb)  
Geräuschspannungsabstand (IHF A)  
Eigangimpedanz/-empfindlichkeit  
Spannungsversorgung  
4 bis 100.000 Hz  
1000  
4 ohms nominal  
120 dB  
Minimum 4 Ohm  
120 dB  
33 k Ohms/1.0 volt  
33 k Ohms/1,0 V  
230 Volts, 50 Hz  
400 Watt  
Power Requirements  
115 Volts, 60 Hz or  
230 Volts, 50 Hz  
Max. Leistungsaufnahme  
Power Consumption  
400 Watts  
Abmessungen (B x H x T)  
440 x 121 x 305 mm  
10.2 kg  
Dimensions (W x H x D)  
440 x 121 x 305 mm  
173/8 x 43/4 x 12"  
Nettogewicht  
Weight (net)  
10.2 kg, 22.4 lb.  
Änderungen, die dem technischen Fortschritt dienen, bleiben vorbehalten.  
All specifications are accurate at the time of printing.  
Rotel reserves the right to make improvements without notice.  
Fiche technique  
Características Técnicas  
Puissance de sortie continue  
(20 Hz à 20 kHz, 0,03 %, 8 ohms)  
130 watts par canal  
Potencia Continua de Salida  
(20-20.000 Hz, THD menor del < 0’03%, 8 ohmios)  
130 vatios/canal  
Distortion harmonique total (20-20k Hz, 8 ohms) 0.03 %  
Distortión Armónica Total (20-20.000 Hz, 8 ohmios) < 0’03%  
Distortion d’intermodulation (60 Hz : 7 kHz, 4:1) 0.03 %  
Distortión por Intermodulación (60 Hz : 7 kHz, 4:1) < 0’03%  
Résponse en fréquence ( +0.5, -3dB dB)  
4 Hz à 100 kHz  
Respuesta en Frecuencia ( +0’5, -3dB dB)  
4Hz-100.000 Hz  
Facteur d’amortissement (20-20,000 Hz, 8 ohms) 1000  
Factor de Amortiguamiento (20-20.000 Hz, 8 ohmios) 1000  
Impedancia de las Caja Acústicas (modo Normal) minima de 4 ohmios  
Relación Señal/Ruido (norma IHF/ ponderación A) 120 dB  
Impédance (mode normal)  
Rapport signal/bruit (IHF A network)  
Impédance d’entrée/Sensibilité  
Alimentation  
4 ohms minimum  
120 dB  
33 kohms/1.0 volt  
Sensibilidad/Impedancia de Entrada  
Alimentación  
33 kohmios/1’0 V  
115 Volts, 60 Hz ou  
230 Volts, 50 Hz  
115 voltios/60 Hz  
230 voltios/50 Hz  
Consommation  
Dimensions (L x H x P)  
Poids (net)  
400 Watts  
Consumo  
400 vatios  
440 x 121 x 305 mm  
10.2 kg  
Dimensiones (An x Al x P)  
Peso Neto  
440 x 121 x 305 mm  
10.2 kg  
Toutes les spécifications de cet appareil étaient exactes au moment de  
l’impression de ce guide. Rotel se réserve le droit de les modifier sans  
préavis.  
Todas estas especificaciones son correctas enel momento de la  
impresión del presente manual de instrucciones.  
Rotel se reserva el deracho a realizar modificaciones en las mismas sin  
aviso previo.  
?
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RB-981  
STEREO POWER AMPLIFIER  
The Rotel Company, Ltd.  
10-10 Shinsen-Cho  
Shibuya-Ku  
Tokyo 150-0045  
Japan  
Phone: +81-3-5458-5325  
Fax: +81-3-5458-5310  
Rotel Deutschland  
Kleine Heide 12  
D-33790 Halle/Westf.  
Germany  
Phone: 05201-87170  
Fax: 05201-73370  
Rotel of America  
54 Concord Street  
North Reading, MA 01864-2699  
USA  
Phone: 978-664-3820  
Fax: 978-664-4109  
082 OMRB-981  
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