DIY stores, hotels, big offices and department stores all have one thing in common: they are extensive and therefore require many speakers. For a system with one or more amplifiers and many speakers, though, you would need a high intensity of current. However, this means thick cables with cabling distances as short as possible. Laying cables like these requires great effort and expense, a problem solved by the 100V line technique.
In the 100V line technique, a transformer used to be integrated between PA amplifier and 100 V speaker. Today, this transformer is already built into the PA amplifier. It raises the output voltage of the amplifier to 100 V. An additional transformer, which transforms the 100 V current to a level suited for the speaker, precedes the speaker or is built into it. Due to the high voltage, audio signals can be transmitted via thin cables for hundreds of metres without great losses.