Rotel Guide to Bridged Mono Operation and Troubleshooting for RB-981 Amplifier
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STEREO POWER AMPLIFIER RB-981

Bridged Mono Operation

[See Figure 3 for bridged operation jumper setting and connec- tion illustration.]

The two channels of the RB-981 can be “bridged”. In this configu- ration the single channel produces a massive 360 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.

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 technician. 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.

Resetting Jumpers

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.

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.

Troubleshooting

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:

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.

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.

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.

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.

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.

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Contents RB-981 Risk of Electric Shock Do not Open Stereo Power Amplifier RB-981 Rotel RB-981 English About RotelGetting Started AC Power and Control Input Signal Connection Speaker ConnectionTroubleshooting Bridged Mono OperationFrançais Table des matièresEmplacement Un mot sur RotelPréliminaire Quelques précautionsAlimentation et commutateur général Prises d’entréePrise de courant secteur Commutateur 1 et témoin d’alimentationUtilisation de l’appareil en mode ponté Raccordement des enceintesDépannage Inhaltsverzeichnis Sicherheits- und WarnhinweiseDeutsch Die Firma RotelZu dieser Anleitung Einige VorsichtsmaßnahmenNetzspannung und Bedienung EingängeNetzanschluß Netzschalter 1 und BetriebsanzeigeLautsprecher BrückenschaltungBei Störungen Italiano IndiceIstruzioni di Sicurezza per l’RB Attenzione Numeri in grassetto fanno riferimento alle illustrazioniAlcune parole sulla Rotel Per cominciareAlcune precauzioni PosizionamentoCollegamento alla rete e controlli Collegamenti per i segnali in ingressoIngresso in corrente alternata Interruttore 1 e spia di accensioneConfigurazione mono a ponte Collegamento dei diffusoriRicerca dei guasti Contenido Español Acerca de RotelPara Empezar Algunas PrecaucionesAlimentación y Control Conexión de la Señal de EntradaToma de Corriente Eléctrica Circuitería de ProtecciónConexión de las Cajas Acústicas Funcionamiento en Modo Monofónico PuenteadoProblemas y Posibles Soluciones Specifications Technische DatenFiche technique CaratteristicheRB-981

RB-981 specifications

The Rotel RB-981 is a powerful stereo power amplifier that has carved a niche among audiophiles and music enthusiasts since its launch. Known for its combination of solid performance, high build quality, and innovative technology, the RB-981 offers a multitude of features that enhance audio reproduction.

One of the standout characteristics of the RB-981 is its robust output capability. With a power rating of 130 watts per channel at 8 ohms, this amplifier can drive a wide range of speakers with ease, ensuring that dynamic musical passages are delivered with clarity and authority. The dual-mono design further enhances its performance by allowing each channel to operate independently, which minimizes crosstalk and distortion for a more immersive listening experience.

The RB-981 utilizes Rotel's proprietary Class AB amplification technology. This design strikes a perfect balance between the efficiency of Class D and the sound quality typical of Class A amplifiers. The result is a rich, warm sound with excellent detail retrieval across the frequency spectrum. Whether reproducing delicate acoustic instruments or powerful orchestral arrangements, the RB-981 maintains composure and provides a listening experience that is both engaging and satisfying.

Another notable feature of the RB-981 is its high-current capability, which allows it to effectively handle low-impedance loads and dynamic musical transients. This characteristic is crucial for maintaining stability during peaks in performance, ensuring that the audio remains clean and undistorted.

In terms of build quality, the RB-981 is solidly constructed with a chassis designed to minimize resonance and vibration. The amplifier also features extensive internal shielding to protect against electromagnetic interference, further enhancing the sound quality. The hefty transformer and high-quality capacitors ensure that the amplifier has the necessary headroom for demanding audio signals.

For connectivity, the RB-981 offers balanced XLR and unbalanced RCA inputs, allowing versatile integration into various audio setups. This modularity ensures that it can be seamlessly paired with a range of preamplifiers and audio sources.

In summary, the Rotel RB-981 is an impressive power amplifier that successfully combines power, precision, and versatility. Its robust construction, advanced technologies, and high-fidelity sound make it an excellent choice for anyone looking to elevate their audio experience. Whether you're a casual listener or a dedicated audiophile, the RB-981 stands as a testament to Rotel's commitment to performance and quality in audio equipment.
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