Toa A-503A Manual page 8

TOA Electronics Amplifier Guide
More complex systems include all these same stages — sources, mixing, processing, amplification, and
speakers — but may add additional signal paths (called busses) so that some sources or listening
areas can be treated differently. A common addition to the typical paging system is the Music On
Hold (MOH) output bus. This bus is fed from the music input, and not affected by speaker processing
modules or by mute functions used for the overhead paging (see fig. 2).TOA 900 Series amplifiers can
provide an MOH output using the T-12S module, which provides for both the music input and the
MOH output. This module also works with the 900 Series mute bus to allow for muting of the music
during paging announcements to the main output, while the separate MOH output is not muted and
receives no page announcement. TOA BG and BG-M Series amplifiers include MOH outputs as stan-
dard features.
Sources
PBX
Phone System
Microphone
Music Source
Figure 2: Basic System Plus Music-On-Hold Output
Zone paging and multimedia systems can use additional signal paths to route sounds to different
areas (see figs. 3 and 4). Figure 3 shows a typical 3-zone paging system for central mic and/or tele-
phone paging with background music. Simple contact closures, provided by the phone system or
contractor, are used to activate the zones in any desired combination, simultaneously muting the
background music in each activated zone. TOA BG-M Series amplifiers offer an especially economical
solution for this type of zone paging system. The background music may be from sources local to
each zone or distributed from the head-end via the MOH output.
In multimedia applications, multiple signal paths can be used to route speech and music or movie
sound to different speakers, allowing precise matching of speaker type for the intended application.
Figure 4 shows a multimedia system for a lecture hall, training room, or multi-media-ready meeting
room. This system provides for stereo playback of music sources and stereo sound for video, using a
pair of speakers which may be located flanking a fixed or retractable screen, alongside distributed
mono speech. The resulting system can provide powerful and moving reproduction of music and
movie soundtracks and clear, intelligible speech. An optional subwoofer for the music feed further
enhances the impact.
Mixer/Amplifier
Processor
Mixer
(optional)
to Phone System
Music on Hold input
5
Speakers
Amplifier