ROTEL RMB-1555 - Manual (Page 10)

10
RMB-1555/RMB-1585 Five Channel Power Amplifiers
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 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 Connections
6
NOTE: The following text describes both binding post and plug-in
connections. DO NOT use both connection methods in combination to
connect multiple speakers.
Turn off all the components in the system before connecting the speakers.
The RMB-1555 and RMB-1585 have two color coded binding
posts, two
for each channel. These connectors 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 amplifier 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 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 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.
Cooling Fans
The Rotel RMB-1585 amplifier is equipped with dual cooling fans to help
ventilate the internal components. The rear panel of the RMB-1585 includes a
3 position fan speed selection switch including Fan Off, Fan Low Speed and
Fan High Speed. Please select the fan speed that best suits the installation
and cooling requirements considering that higher speed fan will provide
more cooling.
NOTE: The RMB-1585 produces significant power and associated heat -
even with the cooling fans in use. Appropriate installation and ventilation
is required to ensure proper operation.
Most likely, you will never see this protection circuitry in action. However,
should a faulty condition arise, the amplifier will stop playing and the Power
Indicator on the front panel will blink.
If this happens, turn the amplifier off, let it cool down for several minutes,
and attempt to identify and correct the problem. When you turn the amplifier
back on, the protection circuit will automatically reset and the Power Indicator
should light up, indicating that the amplifier is turned on normal.
In most cases, the protection circuitry activates because of a fault condition
such as shorted speaker wires, or inadequate ventilation 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 authorized Rotel dealer for
assistance in troubleshooting
Input Signal Connections 234
The RMB-1555 and RMB-1585 have conventional RCA type input connectors,
the type found on nearly all audio equipment. The RMB-1585 also includes
Balanced input connectors. Only one set of inputs should be connected.
Never connected both Balanced and RCA inputs at the same time.
NOTE: To prevent loud potentially damaging noises, make sure the amplifier
is turned off when you make any changes to the input signal configuration.
Select high quality audio interconnect cables. Connect each of the outputs
from the preamplifier or signal processor to the corresponding input of the
amplifier.
Speaker Connection
Speaker Selection
We recommend using loudspeakers with a nominal impedance of 4 ohms
or higher with the RMB-1555 and RMB-1585. You should exercise some
caution 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 RMB-1555 or RMB-1585.
See your authorized Rotel dealer if you have any questions.
Speaker Wire Selection
Use insulated two-conductor stranded wire to connect the amplifier 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.