Input Signal Connections, Speakers | Rotel RMB1575BK, RMB-1565

8	RMB-1565 / RMB-1575 Five Channel Power Ampliﬁers

+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 ampliﬁer 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 ampliﬁer 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 ampliﬁer if safe limits are exceeded.

In addition, the ampliﬁer includes over-current protection which operates only when load impedances drop too low. This protection is independent for each of the ﬁve channels .

Should a faulty condition arise, the ampliﬁer channel at fault will stop playing and the PROTECTION LED on the front panel will light.

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 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 ﬁve ampliﬁer channels. These RCA inputs accept audio signals from preampliﬁers or surround sound processors. Use high quality audio interconnect cables for best performance.

Speakers

The RMB-1565 and RMB-1575 have ﬁve sets of speaker connectors, one for each ampliﬁer channel.

Speaker Selection

The nominal impedance of the loudspeaker(s) connected to each channel of the ampliﬁer in the various operating modes should be no lower than 4 ohms.

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 appropriate 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 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 ampliﬁer 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 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 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).