Efficient signal transmission for large sound systems
In train stations, airports and shopping centres, sound systems often have to bridge hundreds of metres of cable to supply numerous loudspeakers. If these distances are realised using conventional low-impedance operation, the transmitted power drops noticeably, and cable costs rise significantly. This is exactly where 100-volt technology comes in.
What is 100-volt technology?
100-volt technology is a method of transmitting audio signals. Rather than raising its output signal to 4 or 8 ohms, as in low-impedance operation, the amplifier maintains a constant rated output voltage of 100 volts. A transformer integrated into the loudspeaker then steps this voltage back down to the appropriate impedance for the driver. The term “100-volt technology” describes a standardised reference voltage, not a physical constant.
Advantages over low-impedance operation
At the same power level, current decreases as voltage increases. This reduces line losses and allows thinner, more cost-effective cable cross-sections even over long transmission distances. In addition, a single amplifier line can supply numerous loudspeakers in parallel, without the overall impedance dropping with each additional loudspeaker and overloading the amplifier. While low-impedance operation does not require a transformer in the signal path, it is only suitable for short distances and a small number of loudspeakers, as is typical in hi-fi applications. For large, branched systems, 100-volt technology remains the dominant solution in practice.
Power tappings and system design
Every 100-volt loudspeaker has a transformer with several tappings, power tappings, for example 6 W, 3 W or 1.5 W. These tappings allow the power consumption of each loudspeaker to be set independently of the other loudspeakers on the line. One basic rule applies during planning: the sum of all set power tappings must not exceed the amplifier’s rated power. A safety margin of 10-20% is common practice to allow for ageing and component tolerances.
Relevance for EN 54-24-certified systems
Voice alarm systems compliant with EN 54-24 are subject to strict requirements for monitoring loudspeaker lines. The system must automatically detect and report cable breaks and short circuits, so that emergency announcements reach every area in a real event. End-of-line resistors at the end of each loudspeaker line, together with continuous impedance measurement, make this permanent monitoring possible, a core component of any standard-compliant voice alarm system.
All ic audio loudspeakers with a “T” in the product name have an integrated 100-volt transformer and are therefore designed for use in 100-volt systems. An overview of our full range can be found in our product catalogue.
