Why Transformer is connected in some Speakers? Distributed Audio System

In the above picture, you can see here is a ceiling speaker is shown. A transformer is connected to this speaker. But do you know what is the use of this transformer? You may think that it is used for amplifying purposes but it is wrong because a transformer cannot be used as an amplifier. Read the Reason Here.
So in this article, we are going to know why Transformer is connected in some speakers.

The speakers that are used in a Distributed Audio System or Distributed Speaker System or Constant Voltage Speaker System have transformers connected inside them. So if you know about the distributed speaker system then you will know why transformers are used in some speakers. So let's go to learn about distributed speaker systems.

Distributed Speaker System

Distributed Speaker System is nothing but the technique of connecting multiple speakers in parallel. In this technique, a constant voltage (generally 100V or 70V) is maintained in the whole distribution network which is why it is also called a constant voltage speaker system.

If the voltage of the system is 100V then it is called a '100 Volt Line' or '100 Volt distribution system'
If the voltage of the system is 70V then it is called a '70 Volt Line' or "70 Volt distribution system'

In Offices, auditoriums, cinema halls, and airports, the distributed speaker system is used.

The amplifier used in a distributed speaker system has a step-up transformer inside it which increases the voltage and decreases the current. The step-up transformer inside the amplifier increases the voltage up to the standard constant voltage level of the distributed network which may be 100V or 70V.

Each speaker used in the distributed audio system has a step-down transformer inside them which decreases the voltage from the standard constant voltage level(100V or 70V) to the appropriate speaker voltage.

In the above figure, you can easily understand the distributed audio system. Actually, the way of connecting multiple speakers to an amplifier in a distribution audio system is the same as the way of the electricity distribution system. Here the amplifier can be considered as an electricity generating station and individual speakers are considered as substations or loads.

Transformer inside Speaker

So the transformer connected inside the speaker is used for voltage step-down purposes. Each speaker connected in a distributed speaker system has an individual step-down transformer.

These transformers are called Audio transformers. These transformers have two sides - the primary side and the secondary side. The primary side of the transformer is rated in watts and the secondary side of the transformer is rated in ohms.

The primary side of the transformer has input tappings such as 5W, 10W, 15W, and 20W. The primary side has a common line also. The feed cable coming from the amplifier is to be connected to the common line and any one terminal from the tappings. The tapping terminal is to be selected according to the relative volume requirement. For example, if we need the highest relative volume, then we should connect the 20W terminal but if we need the lowest relative volume, then we should connect the 5W terminal.

The secondary side of the transformer has one common line and output tappings such as 4ohm, and 8ohm. The terminals of the speaker are to be connected to this side. 8ohm speaker is to be connected to the common line and the 8 Ohm tap whereas 4 Ohm speaker is to be connected to the common line and 4ohm tap.




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