Input Select Switches; Channel Leds; Bridged Mono Leds; Signal Connections - Rotel RB-976 MkII Manual De Instrucciones

RB-976 Six-Channel Power Amplifier
MkII

Input Select Switches

Channel LEDs

Bridged Mono LEDs

A rear panel switch adjacent to the inputs selects
Stereo mode or Bridged Mono mode for each
of the three pair of amplifier channels.
For Stereo mode: Slide the switch associ-
ated with the desired pair of amplifier chan-
nels to the right, use both LEFT and RIGHT input
connectors, and connect one speaker to each
pair of speaker connectors. The two correspond-
ing front panel CHANNEL indicators will light.
: For groups "B" and/or "C", you can
NOTE
also place the INPUT SELECT switch in the
center LINK position for Stereo mode. This
routes the input signals from the "A" group to
the inputs for that pair of amplifier channels.
For Bridged Mono mode: Slide the switch
to the left, use only the LEFT INPUT connec-
tion, and connect only one speaker to the two
outer speaker connectors. The front panel
CHANNEL LEDs will be extinguished and the
BRIDGED MONO LED will light to indicate
Bridged Mono mode.

Signal Connections

The RB-976 provides standard conventional
MkII
input connections — unbalanced RCA type
connections as found on nearly all audio
equipment.
There is also a pair of SIGNAL OUTPUT LINK
connections for passing the input signal con-
nected to the "A" pair of channels on to an-
other audio component. Additionally, the in-
put signal to the "A" pair of channels can be
automatically linked to the inputs for the "B"
and/or "C" channels, so that a separate in-
put signal cable is not required for those chan-
nels, for example in large systems where the
RB-976 is being used to drive multiple pairs
MkII
of speakers in stereo mode.

RCA Inputs

See Figures 2 and 3
There are two RCA inputs for each of the three
pair of amplifier channels. These RCA inputs
accept audio signals from preamplifiers or sur-
round sound processors. Use high quality audio
interconnect cables for best performance.
For Stereo operation, use both inputs for
that pair of channels. Connect the left chan-
nel output of your preamp to the LEFT INPUT
on the RB-976 . Connect the right channel
MkII
of your preamp to the RIGHT INPUT. Make
sure that the INPUT SELECT switch is in the
STEREO position.
: You can link the inputs for group "A" to
NOTE
groups "B" and/or "C" by placing the IN-
PUT SELECT switch in the center LINK posi-
tion. No input connection is required for that
group. Placing the switch in this position
leaves that pair of channels in Stereo mode.
For Bridged Mono operation, use only
the LEFT INPUT for that pair of amplifier chan-
nels. Connect one output channel of your
preamp to the LEFT INPUT on the RB-976
Make sure that the INPUT SELECT SWITCH
selector switch is in the BRIDGED position.

Input Level Controls

Three controls on the front panel, one for each
pair of amplifier channels, provide input level
adjustments. These allow you to adjust the gain
of the amplifiers to match other components
in an elaborate system.
Turn the control clockwise to increase gain.
Turn counterclockwise to reduce gain.

Signal Output Link

This pair of RCA connections can be used to
pass unprocessed input signals to another audio
component, for example to "daisy-chain" an
additional amplifier to drive a second set of

speakers.

The input signals connected to the "A" inputs
are always available at SIGNAL OUTPUT LINK
connections. These input signals can also be
linked to the "B" and/or "C" inputs by play-
ing the INPUT SELECT switch associated with
that pair of inputs in the LINK position.
10
Speakers
The RB-976 has three groups of speaker
MkII
connectors, one for each pair of amplifier chan-
nels. These can be used to connect two loud-
speakers in Stereo mode, or to connect one
loudspeaker in Bridged Mono mode.

Speaker Selection

The nominal impedance of the loudspeaker(s)
connected to the RB-976
operating modes should be:
• Stereo mode: minimum 4 ohms
• Bridged Mono mode: minimum 8 ohms
When driving multiple pairs of speakers con-
nected in parallel to a single amplifier chan-
nel, the effective impedance the amplifier sees
is cut in half. For example, when driving two
8 ohm speakers, the amplifier sees a 4 ohm
load. When driving multiple speakers in par-
allel, select speakers with a nominal imped-
ance of 8 ohms or higher.

Speaker Wire Selection

.
MkII
Use insulated two-conductor stranded wire to
connect the RB-976
MkII
size and quality of the wire can have an au-
dible effect on the performance of the system.
Standard speaker wire will work, but can re-
sult 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 orienta-
tion 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 iden-
tify the two conductors. There may be ribs or
a stripe on the insulation of one conductor.
The wire may have clear insulation with dif-
ferent color conductors (copper and silver).
There may be polarity indications printed on
the insulation. Identify the positive and nega-
tive conductors and be consistent with every
speaker and amplifier connection.
in the various
MkII
to the speakers. The