Installations
Figure 5. Balanced wiring of a 1/4Ó (6.3 mm) three-wire phone plug.
Figure 6. Unbalanced wiring of a 1/4Ó (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 (Ð) and Audio Ground input connections. See Figure 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 (ÒbalancedÓ) configuration, if possible, to lessen the possibility of interference being picked up by the cables.
Since the input jack and barrier screws for each channel are connected in parallel, only one of these should be used unless the same signal is to be connected in parallel to another amplifier channel.
The input impedance of the Alesis amplifiers is 20 kΩ in balanced or unbalanced configuration. Thus, the inputs of several amplifiers may be connected in parallel if desired. The maximum number of amplifier channels will depend on the minimum output load impedance of the device feeding the amplifiers. For example, if the minimum output load impedance of the source device is 600ÊΩ, up to 30 amplifier channels may be connected to it in parallel without overloading the source deviceÕs output.
To use the amplifier in Bridged Mono mode, connect the input signal to Channel A only and move the recessed slide switch to the Bridged Mono position. The Channel B input will be inactive. See below for output wiring in Bridged Mono configuration.
Audio Installation: Output Wiring
Warning: Be sure that the AC power is off prior to connecting or disconnecting any signal wiring.
Alesis amplifiers can reliably drive 2 Ω loads in Stereo mode and 4 Ω loads in Bridged Mono mode. However, the impedance of a loudspeaker varies with frequency, and its nominal rated impedance is not necessarily its minimum impedance. Some loudspeakers carry both nominal and minimum impedance specifications, and some are supplied with impedance curves. When connecting
Matica 500/900 Reference Manual | 9 |
