Welcome to HowToAV.tv - Today we are looking at 100 volt line audio and explaining where
it would be used and why.
100 volt line audio is mainly used in public address and low level background music systems.
It simplifies the installation of multiple speakers and allows the audio to be sent over
longer distances with a smaller gauge cable when compared with low impedance music amplifiers
used in a Hi-Fi or foreground / live performance music system.
A 100 volt line system can also be referred to as a 'constant voltage' or a 'high impedance'
system. When you are in an office block, waiting for
a flight at the airport, or at an outdoor event and you hear a paging announcement,
it will probably be through a 100V line audio system.
For a 100 volt system you will need a suitable public address amplifier and speakers that
have a transformer fitted. As 100 volt line PA systems are commonly used these are readily
available. Microphones and music sources such as CD players and MP3 players will easily
connect into the amplifier and require no modification or extra equipment.
You will need to select an amplifier that has the correct number of audio inputs that
you need, each audio source requires it's own input.
Then choose the amount and type of speakers that you want to install. Speakers often have
a choice of power settings to choose from. These are called tappings or taps. Choose
which ever is the most appropriate for your job. The higher the tap, the louder the sound
is from the speaker. It makes sense to use the lowest possible tap for your installation.
As an example a ceiling speaker might have a six watt, three watt and one and a half
watt tap. You can have twice has many speakers on a three watt tap as you can if you had
used the six watt tap on all of your speakers. You can combine different types and power
ratings of speakers dependent on the room size, sound levels needed and the environment
it is installed into. They don't all have to be the same speakers. Add up the wattage
of your speakers and pick an amplifier that exceeds the load of the speakers and has the
number of audio inputs you need.
When it comes to wiring up the speakers, they can all be wired in parallel and "daisy chained"
together without worrying about the impedance of the system. There is no messing around
with series and parallel wiring to match the amplifier on a 100 volt line system. You
can go speaker to speaker or even star wire from a central point. The golden rule is that
the combined speaker wattage of all the speakers in the system should not exceed the output
wattage of the amplifier.
When selecting the type of loudspeaker cable, remember that the system is running at a high
voltage and impedance and, therefore, the electrical current flowing in the speaker
cable is very low. An office PA system with perhaps twenty, 6 watt ceiling speakers , will
only need a 0.5mm twin speaker cable and the speakers can be up to one hundred and thirty
meters away from the amplifier.
So that's 100v line audio - an ideal solution for commercial PA systems and large scale background
music. If you'd like more information or advice on
your next PA system project, then HowToAV are the go-to team. Our experts in audio system
architecture consult and design many of the UK's most largest and most complex professional
PA systems. So contact them on the number shown now.
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