8
RMB-1565 / RMB-1575 Five Channel Power Amplifi ers
+12V Trigger Input and Output
5
The jack labeled IN is for connecting the 3.5mm Plug/Cable carrying
a +12 volt trigger signal to turn the amplifi er on and off. To use this
feature the adjacent switch must be placed to the 12V TRIG position
(see previous section). This input accepts any control signal (AC or DC)
ranging from 3 volts to 30 volts.
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.
Protection Indicator
2
Thermal and protection circuits protect the amplifi er against potential
damage in the event of extreme or faulty operating conditions. Unlike
many designs, the protection circuit in the RMB-1565 and RMB-1575
is independent 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 amplifi er if safe limits are
exceeded.
In addition, the amplifi er includes over-current protection which
operates only when load impedances drop too low. This protection is
independent for each of the fi ve channels .
Should a faulty condition arise, the amplifi er channel at fault will stop
playing and the PROTECTION LED on the front panel will light.
If this happens, turn the amplifi er off, let it cool down for several
minutes, and attempt to identify and correct the problem. When you
turn the amplifi er back on, the protection circuit will automatically reset
and the PROTECTION LED should go out.
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.
Input Signal Connections
4
See Figure 2
The RMB-1565 and RMB-1575 have standard unbalanced RCA-type
input connectors, the type used on nearly all audio equipment. There is
an RCA input for each of the fi ve amplifi er channels. These RCA inputs
accept audio signals from preamplifi ers or surround sound processors.
Use high quality audio interconnect cables for best performance.
Speakers
The RMB-1565 and RMB-1575 have fi ve sets of speaker connectors,
one for each amplifi er channel.
Speaker Selection
The nominal impedance of the loudspeaker(s) connected to each
channel of the amplifi er in the various operating modes should be no
lower than 4 ohms.
Speaker Wire Selection
Use insulated two-conductor stranded wire to connect the amplifi er 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 appropriate cables for your system.
Polarity and Phasing
The polarity – the positive/negative orientation of the connections
– for every speaker and amplifi er 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 amplifi er connection.
Speaker Connections
3
See Figure 2
Note:
The following text describes both binding post and plug-in
connections. DO NOT use both connection methods in combination to
connect multiple speakers.
The RMB-1565 and RMB-1575 have two color coded terminals for
each amplifi er channel. These speaker connectors accept bare wire,
connector lugs, or “banana” type connectors (except in the European
Community countries where their use is not permitted).
Route the wires from the amplifi er to the speakers. Give yourself
enough slack so you can move the components to allow access to the
speaker connectors.
If you are using banana plugs, connect them to the wires and then
plug into the backs of the speaker connectors. The collars of the
speaker connectors should be screwed in all the way (clockwise).
