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How It Works







The School Bell melody sounder holds 16 pre-recorded melodies (interchangeable with your own MP3 files). Its function is to indicate breaks or class change times in environments such as schools, factories or workshops. The Sigma master clock can also broadcast a verbal message at the press of a button e.g. “Lock down”, “Intruder”, “Bomb Alert”, “Evaluate School” “All Clear”, “the school bus will be leaving from the front of the school this evening” etc. This can be used as part of your schools Safety Emergency Procedure (SEP).

The master Clock system has an option to have an additional key pad with 4 alert buttons which can be used to get any 3 personalised voice overs such as “Caretaker to call reception” etc. The Wireless melodies when combined with the Sigma master clock, the Melody Sounder can wirelessly play a choice of melodies at pre-programmed times.


  • 4 Versions of melodies: indoor wall mounted or ceiling versions (90 dB)
  • Outdoor wall mounted (90 dB) and wall mounted with horn speaker (120 dB)
  • 3Types of power supply: 100v to 240v AC or 24v D (Melody Speakers) or PoE (Harmonys Speakers)

For synchronisation there are 3 models:

  • DHF; wirelessly controlled by Sigma master clocks with a choice of up to 16 melodies sounding at different times.
  • IP All Speakers can be synchronised through NTP software /  master clock
  • Hard wired; at power up, sounding the melody chosen from the 16 melodies available.