Commercial Audio

We thought we would talk tech today on commercial Audio. There are a lot of questions out there about 70V line transformers and amplifiers, how to hook these up types of speakers etc..
In this blog we will address some of these issues.

Let's start with, what is a 70 Volt Sound System & What it is used for.
A 70 Volt Sound System is comprised of amplifiers, speakers with transformers, microphones, volume controls, a telephone system interface and an assortment of wires used as connections. It is generally used for commercial sound applications where there is need for electronically amplifying and distributing sound for the function of paging, playing music and/or pre-recorded messages to a commercial environment.

What are the benefits of using a 70 Volt Sound System?
A 70 Volt system uses a basis of high voltage to result in a lower current when distributing power to a sound system. By not having excessive, wasted current, long runs of wire can be prevented from overheating. Which makes a 70 Volt Sound System very energy efficient.

Generally 70 Volt systems are more cost effective than an 8 Ohm speaker system when dealing in volume installations.

70 Volt Systems are easier to design than 8 ohm speaker systems. The impedance does not have to be matched throughout the system as would be required in an 8 ohm system.
Because 70 Volt speakers come with transformers impedance is not an issue unless an excessive amount of speakers are going to be installed together.

What is the purpose of a 70V Transformer on a Speaker?
The transformer protects the speaker and only allows a certain wattage to pass through the transformer to activate the speaker depending on the sound requirement. The higher the wattage tap is set or wired the louder the speaker will be. Transformer based systems are current efficient by protecting the system from getting overheated from wasted power.

How do I wire a commercial run of speakers?
Commercial speakers should be wired in a "Parallel Run" meaning the positive outbound connection of the amp. or receiver should run to the positive terminal of the first speaker. That positive terminal wiring should proceed to the next speakers positive terminal. The return wire from each common terminal goes to the next speaker on the return run's common terminal and finishes at the amp.
Large runs with many speakers should be broken down into several smaller runs coming from the amplifier . If one speaker stops working it is easier to locate the problem on shorter runs.

What size wire should I use?
Run's less than 50 feet and 50 Watts or less of power use 16 Gauge
Run's more than 50 and over 50 Watts of power use 14 Gauge.

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*Information provided is for educational purposes please consult licensed professionals when performing commercial installations.