1 paging and distributed speaker system start part ll paging and distributed speaker system start...

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Paging and distributed speaker system

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BASIC TELECOMMUNICATIONS

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As a general rule of thumb, connecting speaker systems in parallel is the more desirable approach for a number of reasons

1) when connected in series, if any individual speaker system fails, none of the speaker systems will work because the circuit is incomplete through all of the speaker systems, no sound will come through any of the speaker systems


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2) when connected in series, speaker systems tend to interact with one another, which can result in distortion

All speaker systems exhibit a damping action, which is the result of the natural resistance of the voice coil in the speaker system against the permanent magnet located nearby


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This damping action, though mechanical in nature, can result in lower signal levels through the speaker system line

This is where daisy chaining can come into play. Speakers may be daisy chained in a parallel install in the ceiling or home run back to the amplifier and daisy chained there using a connection bar


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There is a practical limit to the number of TIC speaker systems that can be effectively connected in parallel

At some point, the amplifier will no longer be able to supply enough power to each of the speaker systems to produce adequate sound


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Example, the maximum current the power amplifier can supply limits the number of speaker systems in parallel.

When we are requested to simply add a speaker to an existing system

Is there room at the AMP? Sufficient voltage and current output?


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As a general rule, you are safe if you limit the number of speaker systems to four; 8-Ohm or eight 16-Ohm per channel, assuming the speaker systems are full range, and the power amplifier is rated at 100 watts per channel

Example, four 8-Ohm speaker systems in parallel results in effective impedance of 2 Ohms, and a current requirement of greater than 7 amperes at 100 watts output


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Combining Series and Parallel; To get around the limitations of an all series connection, or an all-parallel connection.

you can connect multiple speaker systems in a combination of parallel and series


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You can use this technique, for example, to connect four speaker systems together, and still present an effective impedance of 8-Ohms to the power amplifier.

In the diagram, two of the speakers are wired in series, and the two series combinations are wired in parallel.

In the other example 2 sets of 4 speakers are connected in parallel and then both parallel combinations are connected in series......


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Examples of Series/Parallel wiring


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Assuming all four TIC speaker systems are rated at 8-Ohms, the effective impedance for the array of TIC speaker systems is 8 Ohms, so you would connect the array to the 8-Ohm output of the power amplifier

This is why it is better to home run all speakers to a connection bar located near the AMPLIFIER so future changes in wiring can easily be accomplished


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When connecting multiple speaker systems, it is absolutely vital that you observe proper polarity at all times

If you mix the polarity, the sound delivered by your sound system will be substandard

The system may sound excessively “boomy”, and output levels may be substantially diminished

It is also possible some damage to the amplifier or speaker components may occur


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Watch your conductor colors!

70v in-line distribution cable wire run gaugesrecommended maximum wire run for a certain power rate and wire gauge


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Outdoor speaker cable based upon impedance testing 8 Ohm unitsRecommended Cable Gauge (AWG) Vs. Length of Cable Run

±50 Ft.= 18 AWG±100 Ft.=16 AWG ±150 Ft.= 14 / 12 AWG±200 Ft= 12 AWG±250 Ft= 12 /10 AWG±300 Ft. = 10 AWG


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Don’t forget that power and distance have a bearing on the conductor size we use

More wattage output = thicker conductor

Longer distances= thicker conductor

Don’t forget plenum and PVC either!!


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Here we have a typical wall or ceiling speaker with the wattage transformer connected to the speaker, and a close up of the transformer


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Depending on distance and coverage area you can increase the wattage output of the speaker by connecting the appropriate color coded tap wires.


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This diagram shows which color coded leads to tap for specific output wattage, these colors may vary from manufacturer to manufacturer


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According to the consumerreports.org outdoor speaker wireless models are not recommended; "Among the wireless sets we tested, they were prone to interference from devices such as cordless phones, microwave, resulting in static, hissing or clicking".

They have high failure rate for a frequency transmitter, their sound quality is AM radio comparable and made of fragile plastics components which can easily break."


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Ceiling speaker installation procedures….

1) Take the tile you wish to place the ceiling speaker in out of the ceiling.

2) With a pencil and the ceiling speaker on the tile, trace around the speaker completely.

3) With a hacksaw or jigsaw, cut around the hole you just made in the ceiling tile.


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4) Screw the ceiling speaker's mounting bracket onto the ceiling tile with the included screws.

5) Place the ceiling tile back into the ceiling.

6) Put the speaker up onto the tile onto the mounting bracket and secure it with the included screws.

7) Wire the ceiling speaker to the speaker wire and secure them with wire caps.


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8) Place the speaker grille onto the ceiling speaker and secure it with screws if needed, usually included.

9) Run the speaker wires to the receiver or amplifier.

10)Repeat the process for more ceiling speakers.


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Note that today, most inspectors require that ceiling speaker mount plates (a.k.a. tile bridges) be screwed down to the grid bar being used. We cannot just snap it on there anymore

Also, the speaker mount bar must be secured to the roof deck above at two points

This keeps the kiddies from pushing it upwards


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Many companies (see the big two-Bogen and Valcom) offer easy to install systems that do not require support bars

Note that we cannot simply put a speaker into a tile in most locales anymore. We must support them to the deck with guy wires at two points


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2’x 2’ and 2’ x 4’ceiling speaker-no cutting etc.


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Note that Valcom paging systems specify CAT 3, 4 pair cable for speaker terminations

When installing speakers over 300’ they recommend twisting pairs together to increase the wire guage

In that case the 24 AWG blue pair would be twisted together and the 24 AWG orange pair twisted together to effectively provide a 20 AWG wire pair


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It should be noted that you will follow the manufactures cable type recommendations for wiring speakers to a paging amp

Regardless of the type of cable used, the NEC dictates that wiring used for the distributed audio system shall not share the same raceway or cable tray for cables used in signaling systems and fire alarm system.

Article 725.56 (F) signaling systems, 760.56 (D) fire alarm systems


1 paging and distributed speaker system start part ll paging and distributed speaker system start...

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