3It is always preferable to mount power amplifiers, which generate a certain amount of heat, above heat sensitive equipment, like SM30.If however, power amplifiers must be mounted beneath the Control Centre, a heat shield should be installed above them. This is necessary to deflect the hot air currents, which could otherwise cause instability in the SM30 microprocessor controlled units.
5.5Connecting amplifiers
The SM30 system is intended for use with 2 separate amplifiers, or two separate channels of a multi channel amplifier. One channel will handle the ‘call’ signal, and the other channel will amplify the ‘music’ signal. This allows the music signal to continue, uninterrupted, when a call is made to other loudspeaker zones. It is possible to use only 1 amplifier channel for both the ‘calls’ and ‘music’ signal. This has the disadvantage however, that any music playing will be interrupted whenever a call is made, regardless of the zone(s) to which the call is routed. Though the SM30 system will work with any line level input amplifier, the amplifiers from the Philips SQ45 range have been specifically designed to take the greatest advantage of the functions of SM30.
Two Channel System (fig.5.5.1) Connections of SM30 to two amplifiers, or two channels of a Philips SQ45 amplifier:
1Connect both the ‘Call’ and ‘Music’ outputs of the Line Output Module, to the separate ‘Call’ inputs of the SQ45 amplifier(s).
2Connect the outputs of the amplifiers (with two core loudspeaker cable) to their respective ‘Call’ and ‘Music’ inputs on the
One Channel System (fig.5.5.2)
When using a single amplifier system, the following steps must be taken:
1The ‘Call’ and ‘Music’ outputs of the Line Output Module should be connected to their respective ‘Call’ and ‘Music’ inputs on the SQ45 amplifier. The relay on the Line Output Module will switch the active input of the SQ45 amplifier from music to call.
See the relevant SQ45 amplifier Instructions For Use for details of this function.
2The output of the amplifier has to be connected to the ‘Call’ input on the
3Refer to Installer Program step 9 to program this function.
As previously stated, zones with music will be interrupted for as long as a call to any other zone(s) lasts.
Rack Mounting
If the amplifier(s) and SM30 are mounted in a rack unit, and an ‘earth loop’ occurs (evident by a 50 or 60 Hz hum through the loudspeakers) follow the Instructions For Use given with the SQ45 amplifier for details of earthing the units.
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