4. Electro-technical contexts

Once more: With 100V PA systems, we are dealing with a fundamentally different concept than the traditional music and voice transmission systems. The audience of 100V PA systems will simply never remain static in a single position, a situation which would be appropriate for stereo transmission. With 100V PA systems...

1. ... transmission is therefore always mono.
2. ... only a single amp is required (minimum).
3. ... as many speakers as the amp allows can be hooked up.
4. ... separate amps for every programme to be transmitted are required.
5. ... sound can be transmitted over greater distances than other PA or HiFi systems.
6. ... relatively low wattage (e.g. 120 W) is involved.

Technically speaking, we achieve the longer transmission distances by employing transformers, which step the signal voltage up or down, convert impedance (alternating current resistance) and then adjust it again.

I have explained the circuit principle above.

We can therefore do without greater currents and the concomitant larger cable diameters.

The speakers' output is often less than 10 W and may even be halved or quartered. This also means that the volume, or sound pressure, is reduced. Halving the output means a reduction by 3 dB. By adding the output values of all the speakers, we arrive at the system's total output value.

Ten Watt may not deliver great volume, but to supply a restaurant of 80 square meters with background sound, for example, 40W is actually sufficient.

Furthermore, in such a system we can switch all speakers in parallel without any problems, since their input transformers supply the necessary impedance. In low-ohm circuits (4 Ohm / 8 Ohm) this does not work, since the total impedance quickly reduces to a degree which is dangerous for the amp (this continually overloads the amp and can lead to its destruction).

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