The Soundfusion Telephone Hybrid Is a South African Post Office approved full-range automatic telephone balancing system.
The unit is available In various forms:
1) A single channel/line version in a 1U" 19 inch rackmount unit with hybrid card, interface card and internal power supply.
2) A dual channel/line version in a 1U" 19 inch rackmount unit with dual hybrid cards, an interface card, and internal power supply.
The single and dual versions are housed in the standard Soundfusion extruded aluminium 1 'U' housing with removable front panel for setting levels and removing euro-cards. Audio inputs and outputs are electronically balanced on 3 pin XLR connectors. Telephone line and instrument connections are on a single way Phoenix Contact screw-terminal block (extra terminals for PABX transfer). Control is on a 25 way sub D-type connector and IEC for mains power input. Separate 0 Volt and Chassis terminals also appear on the back panel for strapping or wiring out.
Send and return levels are adjusted by removing the front panel and adjusting the potentiometers situated on the front of the hybrid euro-cards. LED indication of send and return levels, as well as a VOX LED (indication of automatic balancing taking place), are available on the front of these euro-cards.
When the unit is not in operation the telephone operates normally. An Internal opto-coupled circuit on the Interface card detects ringing on the line and will - if requested -give an audible tone via an internal buzzer. At the same time this card will also give an external control to the rear panel remote connector to ring an external buzzer and/or flash an external indicator.
During the initial ringing or dialing out period the output of the hybrid is muted. When "diverted", the telephone instrument handset is disabled and the line routed Into the hybrid. At the same time the hybrid mute is disabled to allow the signal to feed through to the output. Once diverted, there is a facility to "Talk-to-Caller" whereby a separate line level feed is routed to the caller (i.e. Mic Channel Direct or Talk-back).
The hybrid unit has an in-built send limiter and return expander in order to clamp/expand the audio levels to required limits. These devices are fitted in order to enhance the automatic balancing network.
