Audio 4+1 systems are the most common type of intercom and the most traditional, perhaps the oldest type of door entry intercom. Referred to as AC buzzer type intercoms. The technique is very simple and many manufactures still make this type of system.

In the last few years the introduction of Electronic call systems have overtaken and are  now the most common in the market place, the handsets no longer have an AC buzzer which is considered by many as having a harsh tone, electronic call is much softer, the handsets are not as interchangeable across manufactures as the AC type, manufactures differ in how the intercom generates the tone at the handsets, some handsets generate the tone locally, while other manufactures generate the tone at the power supply.

The handsets don’t suffer so much from interference and the audio is much clearer.

Video 4+1 has overtaken the more traditional RG-59 Co-axle plus multi core cable, it was introduced originally to replace the traditional Audio systems, upgrading from Audio to Video without the cost and disruption of wiring. The systems are available in Mono or Colour, they are also electronic call, with the introduction of the new Exhito monitors, you also have the choice of Echos Colour handsfree monitors, in White or Silver finish, surface of Semi flush.

External panels for Audio or Video can be Agora, Profilio or Matrix. For technical information on the 4+1 systems download the No 11 technical manual.

Audio or Video 2 wire Duo is the latest in wiring systems, designed for ease of installation and utilising more electronics than the more traditional 4+1 type systems, analogue or digital, benefits such as the use of less skilled labour, installation is quicker as there are only two connections though out the system.

Giving savings on cable and labour, the initial cost of the equipment is higher than the more traditional systems, but as technology improves and the systems become more and more popular the equipment cost will begin to fall.

The Duo systems use the Agora, Profilo and Matrix external panels and the Exhito and Echos handsets and monitors. For more information one the Duo system download the Duo leaflet and for technical information download the No 13 technical manual.