Commercial Audio and Video

Constant-voltage speaker systems refer to networks of loudspeakers that are connected to an audio amplifier using step-up and step-down transformers to simplify impedance calculations and to minimize power loss over the speaker cables. Systems like this have been around for nearly 100 years and were invented in response to the need for large public address installations that required a large number of loudspeakers. These systems use higher voltage and lower current to distribute the signal using lower gauge wire. In Canada and the US these systems are most commonly referred to as 70-volt systems. 

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Few systems are as misunderstood as "70V" systems.  The most important trait of these systems is the use of transformers that are used to "step down" the signal voltage before applying it to the loudspeaker. This is necessary because the signal voltage is "stepped up" at the amplifier. Myths regarding these systems abound. Some are rooted in fact, others, not so much. 

 

This type of application works well when you need a large quantity of speakers.