Rotel RMB-1080 Speaker Connection, Protection Circuitry, Input Selector Switch, Speaker Selection

Protection Circuitry

The RB-1080 features a thermal protection cir- cuit that protects the amplifier against potential damage in the event of extreme or faulty operating conditions. Unlike many designs, the RB-1080’s protection circuit is indepen- dent 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 tem- peratures exceed safe limits.

Most likely, you will never see this protection circuitry in action. However, should a faulty condition arise, the amplifier will stop play- ing 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 iden- tify and correct the problem that caused the protection circuitry to engage. When you turn the amplifier 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 ventilation lead- ing to an overheating condition. In very rare cases, highly reactive or extremely low im- pedance speaker loads could cause the pro- tection circuit to engage.

If the protection circuitry triggers repeatedly and you are unable to isolate and correct the faulty condition, contact your authorized Rotel dealer for assistance in troubleshooting.

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Input Signal Connections

The RB-1080 gives you a choice of two dif- ferent kinds of input connections – conven- tional unbalanced RCA type connections (such as found on nearly all audio equipment) or balanced XLR-type connections for use with some high-end preamps or digital processors featuring this lower noise connection.

NOTE: To prevent loud potentially damag- ing noises, make sure the amplifier is turned off when you make any changes to the input signal configuration.

Input Selector Switch

Set the switch to select the inputs that are be- ing used. Set it to Unbalanced if the RCA inputs are used. Set it to Balanced if the XLR inputs are used.

RCA Inputs (unbalanced)

See Figure 2

When a component with RCA connectors – such as a preamplifier or surround sound pro- cessor – supplies signals to the RB-1080, the RCA-type phono plug inputs should be used.

Select high quality audio interconnect cables. Connect each of the outputs from the pream- plifier or signal processor to the correspond- ing Unbalanced Input of the RB-1080.

XLR Inputs (balanced)

See Figure 3

If you are using one of the high-end pream- plifiers or processors with low-noise balanced signal outputs to drive your RB-1080, you may choose to use these low-noise XLR-type con- nections. See your authorized Rotel dealer for the appropriate cables.

Connect XLR audio interconnect cables from each of the outputs from the preamplifier or signal processor to the corresponding Bal- anced Input of the RB-1080.

English

Speaker Connection

Speaker Selection

We recommend using loudspeakers with a nominal impedance of 4 ohms or higher with the RB-1080. 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 amplifier sees a 4 ohm load. When driving multiple speakers in parallel, it is recommended that you select speakers with a nominal impedance of 8 ohms or higher. Speaker impedance ratings are less than precise. In practice, very few loudspeakers will present any problems for the RB-1080. See your authorized Rotel dealer if you have any questions.

Speaker Wire Selection

Use insulated two-conductor stranded wire to connect the RB-1080 to the speakers. The size and quality of the wire can have an audible effect on the performance of the system. Stan- dard 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 spe- cial high-quality speaker cables. Your autho- rized Rotel dealer can help in the selection of appropriate cables for your system.

Polarity and Phasing

The polarity — the positive/negative orien- tation of the connections — for every speaker and amplifier connection must be consistent so all the speakers will be in phase. If the po- larity of one connection is mistakenly reversed, bass output will be very weak and stereo im- aging degraded. All wire is marked so you can identify the two conductors. There may be ribs or a stripe on the insulation of one conductor. The wire may have clear insula- tion with different color conductors (copper and silver). There may be polarity indications printed on the insulation. Identify the positive and negative conductors and be consistent with every speaker and amplifier connection.