P.A. Amplified, Impedance Balanced & Constant Voltage Paging Equipment - Although theses technologies still exists, they are usually seen in older installations.  They involved using one or more P.A. (Public Address) Amplifiers and standard or transformed speakers and horns.  The P.A. Amplifiers usually had 4, 8 and 16 ohm outputs for "Impedance Balanced" speakers and 25/70 Volt outputs for "Constant Voltage" speakers with transformers attached.  Impedance Balanced systems were the worst.  The idea was that no matter how many 8 Ohm speakers you used, the combined load could not be more than 4 ohms or not less than 16 ohms when presented at the amplifier.  This often involved elaborate "series-parallel" wiring schemes.  Normally, this technology would not be used in new installations except for applications such as airports or sports arenas.  However, if you have an existing paging system that uses this technology, we have replacement speakers, horns and amplifiers to replace failed components. Constant Voltage technology was an improvement over Impedance Balancing because it eliminated the need for elaborate wiring.  Each speaker or horn was daisy-chained.  Each speaker or horn had a transformer attached to it and a technician would normally select one of several lugs to attach the wire to, depending on how loud the speaker needed to be.  The selections were measured in watts and used solder type lugs.  Many techs didn't understand the relationship between watts (power) and sound levels (decibels).  Then, there was the likelihood of them owning a soldering guns, having a spool of solder and then wanting to drag a 100 foot extension cord up a ladder to solder to connection.