Alesis RA300, RA150, RA500 manual To use an unbalanced source with an Alesis amplifier

Connections: Chapter 2

Warning: Be sure that the AC power is off prior to connecting or disconnecting any signal wiring.

The input circuits of the Alesis amplifiers are electronically balanced. They may be fed from either symmetrical (“balanced”) or unbalanced sources. On the RA300 and RA 500, there are two combination XLR/1/4” (6.3 mm) jacks provided, one for each channel.

Figure 3. Balanced wiring of an XLR input

connector.

Figure 4. Unbalanced wiring of an XLR input

connector.

Figure 5. Balanced wiring of a 1/4” (6.3 mm) three-

wire phone plug.

Figure 6. Unbalanced wiring of a 1/4” (6.3 mm)

three-wire phone plug

All input wiring should be done with shielded cable.

To use an unbalanced source with an Alesis amplifier:

Connect the High (+) signal wire as shown in Table 1 and connect the shield wire to both the Low (–) and Audio Ground input connections. See Figures 4 and 6. If a two-wire (tip and sleeve only) phone plug is used for an unbalanced input, the sleeve of the plug will automatically connect the Low and Audio Ground connections together inside the amplifier.

Long input cable runs, particularly in areas with high electrical interference, should be done with symmetrical (“balanced”) configuration, if possible, to lessen the possibility of interference being picked up by the cables.

Only one input jack of a channel should be used at a time: don't use the 1/4"/XLR input jack and phono input jack simultaneously. Do not plug two different sources into the same amplifier channel. While this will not harm the amplifier, the sources may interfere with each other causing distortion.

14 RA150/300/500 Reference Manual