The 70 volt system is utilized primarily in commercial applications where both voice paging and/or background music has to be evenly distributed over a number of speakers, fed by large amounts of speaker cable. If one were to use regular P.A. gear in this application, it would turn into a nightmare of impossible impedance calculations and enormous amounts of very, very thick speaker line. In other words, more trouble than its worth. 70 volt technology has overcome the impedance and power loss problems by utilizing transformers between the amp and speakers. By bumping up the signal after the amplifier, then converting it back to normal levels at the speaker, we are able to overcome the aforementioned impedance and power problems.
It is important to note that most 70 volt mixers/amplifiers have limited band width and cannot reproduce the entire audible frequency range. In most applications where these systems are being used, this is not a big deal. However, with the expertise of companies like Bose, Toa and Altec Lansing, there are now 70 volt systems available to rival some of the best hi-fidelity systems out there.
By: Dwayne Wells
Sales - Axe Calgary
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