8
RB-1581 Bridged Mono Power Amplifi er
The jack labeled OUT is for connecting another 3.5mm plug/cable to
provide a 12V trigger signal to other components. The 12V output signal is
available whenever a +12 volt trigger signal is applied to the IN connector.
Input Signal Connections
3
See figure 2
NOTE:
To prevent loud noises that neither you nor your speakers will
appreciate, make sure the system is turned off when you make any
signal connections.
The RB-1581 provides two types of input connections · unbalanced
RCA type connections as found on nearly all audio equipment as well as
balanced XLR connections.
Select high quality audio interconnect cables. Connect each of the outputs
from the preamplifier or signal processor to the corresponding input of the
amplifier.
Input Selector Switch
A toggle switch in the rear panel selects the type of input signal to use.
Select the correct inputs to use with this flip switch.
NOTE:
You should choose only one method of analog connection from
a source component to RB-1581. Do not connect both the RCA and
XLR outputs of a source component to the RB-1581 at the same time.
Speaker Outputs
See Figure 2
Speaker Selection
The nominal impedance of the loudspeaker(s) connected to the RB-1581
should be a minimum of 4 ohms. When driving multiple pairs of speakers
connected in parallel, 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, select speakers
with a nominal impedance of 8 ohms or higher.
Speaker Wire Selection
Use insulated two-conductor stranded wire to connect the RB-1581 to the
speakers. The size and quality of the wire can have an audible 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 authorized
Rotel dealer can help in the selection of cables for your system.
Polarity and Phasing
The polarity --- the positive/negative orientation of the connections --- for every
speaker and amplifier connection must be consistent 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 identify the two conductors. There may be ribs or a stripe on the
insulation of one conductor. The wire may have clear insulation 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.
Speaker Connection
6
See Figure 2
Turn off all the components in the system before connecting the speakers.
The RB-1581 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 European Community countries where their use is
not permitted).
Route the wires from the RB-1581 to the speakers. Give yourself enough slack
so you can move the components 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 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 counterclockwise) the binding
post. Place the connector lug or wire around the binding post shaft. Turn the
binding post 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.
