Operatic school PA

In the valve era, the Bland radio company made a centralized PA system for schools in Australia.

The central unit consisted of a preamp for a microphone, turntable, AM radio tuner, and a push-pull amplifier, and switches that would switch it to drive speakers located in the classrooms, and out in the school yard.^[1]

The speakers in the class rooms were a wedge type cabinet design, and were mounted on the wall up high, containing a 20 cm Rola loudspeaker. The "yard" speaker was also a 20 cm Rola, but housed in a large steel horn^[2], that was mounted high up on either the wall of a 2 story school building,^[3] or sometimes on the roof of a school building.

The amplifier delivered a 70 volt line type output that coupled to the speakers via 500 ohm matching transformers, mounted in the speaker inclosures at each locality.

Its Use

Usually this system would be used with the ABC's radio programmes for schools. The teachers would tune the tuner into the programme, and switch it to the appropriate class room or class rooms. This would sometimes also be done, for assemblies outside where the yard speaker would be switched in.

Other Improvization

Schools that did not have such a system, often played a tape, to get the children to march into assembly or set up a radio in the class room and tuned into the "for schools" programmes. The television was also used, and parents would donate old monochorme TV sets to the school, and they would be stationed in most class rooms, where they would tune into the ABC TV For Schools programmes. The TV set would be repaired if it needed a new valve, but not picture tube replacement.^[4]

1. ^ In the living memory of many former school students who went to school in especially the 1970s
2. ^ Examining of the equipment in private collections in Adelaide
3. ^ Yard Speaker still mounted at one Adelaide school
4. ^ memories of the author, a former student of St Peters Anglican Grammer School (campus now demolished), in Glenelg, Adelaide South Australia 1975 to 1979