Speaker Connection
Speaker Selection
We recommend using loudspeakers with a nominal impedance of 4 ohms or higher with the RB-1070. 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-1070. See your authorized Rotel dealer if you have any questions.
Speaker Wire Selection
Use insulated two-conductor stranded wire to connect the RB-1070 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.
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Stereo Speaker Connection 
The RB-1070 has two pairs of color coded binding posts on the back panel. These con- nectors accept bare wire, connector lugs, or dual banana type connectors (except in the European Community countries where their use is not permitted).
Route the wire from the RB-1070 to the speak- ers. 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 thumb- screws 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. Unscrew (turn coun- terclockwise) the binding post hexagonal thumbscrews. Place the connector lug or wire around the binding post shaft. Turn the hex- agonal 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.
Bridged Mono Operation 
[See Figure 3 for bridged operation
jumper setting and connection illus-
tration.]
The two channels of the RB-1070 can be “bridged”. In this configuration the single channel produces a massive 330 watts! This feature allows you to increase the overall power output of your system by bridging the RB-1070 and adding a second bridged RB- 1070. Or the RB-1070 is bridged to drive a monophonic subwoofer. Note however that when the RB-1070 is bridged the speaker con- nected to it must have an impedance of 8 ohms or more.
English
In order to use the RB-1070 in bridged mode, three “jumper” connectors inside the ampli- fier must be moved from one set of pins to another. This task should be done by a qualified technician. See your authorized Rotel dealer. In addition the RB-1070 is connected to the other components in a different way. When the RB-1070 is setup for bridged operation the Bridged Mono indicator light 
on the front panel will light.
Resetting Jumpers
Before opening the RB-1070 cabinet to re- set the jumpers, the power cord must be unplugged from the wall. DO NOT OPEN THE CABINET OF THE RB-1070 BEFORE THE POWER CORD HAS BEEN UN- PLUGGED FROM THE WALL. FAILURE TO DO SO WILL EXPOSE YOU TO HAZARD- OUS 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-1070 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-1070
power cord back into the wall out- let until the cabinet cover has been replaced.
Input Connection
When using the RB-1070 in bridged mono mode, connect the cable from the preampli- fier output to the left input. No connection is made to the right input.
Bridged Speaker Connection
When using the RB-1070 in bridged mono mode, the wire to the speakers is connected to the positive terminals of the left and right channels. Connect the wire that goes to the positive terminal of the speaker to the posi- tive terminal of the left channel of the RB-1070. Connect the wire that goes to the negative terminal of the speaker to the positive termi- nal of the right channel of the RB-1070. No connections are made to the negative termi- nals of the RB-1070.
