Rotel RB-981 Input Signal Connection, Speaker Connection, Speaker Selection, Polarity and Phasing

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.

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.

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.

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.

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.

Speaker Connection

Speaker Selection

We recommend using loudspeakers with a nominal impedance of

4ohms 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.

English

Speaker Wire Selection

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.

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.

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).

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.

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 or wire around the binding post shaft. Turn the hexagonal thumbscrews clockwise to clamp the connector lug or wire firmly in place.

Note: Be sure there are no loose wire strands that could touch adjacent wires or connectors.

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