RTS SSA324 2-Wire to 4-Wire Converter

The SSA324 is a system to system interface. It interconnects voice signals between intercom systems that are otherwise technically incompatible. An optional card makes it possible to pass call-light signals between different system types. The two-wire interface is suitable for balanced (Audiocom) and unbalanced (TecPro, Clear-Com) systems allowing RTS Two-Wire to interface with virtually any party-line systems in use today.
The SSA324 may be used free-standing, or rack-mounted. Alternatively it may be fitted in a console.

Features

– Easy linking to Clear-Com, TecPro and similar intercom types
– Balanced operation may be selected (e.g. to match Audicom products)
– Trim controls for null, level and ducking help keep the voice signal clean
– Simple set-up procedure for two-wire nulling
– Adjustable signal ducking (0dB to 30dB)
– Two level trims per interface (to and from two-wire) optimise operating levels
– Front panel mounted headset outlet for set-up and monitoring
– Rear connectors include terminals to aid making rapid connections in the field
– Optional transformers may be fitted to maximise common mode rejection
– Packaged in a half-rack, 1U metal housing, for durability

Each SSA324 offers a pair of two-wire to four-wire converters (converter A and converter B). It can function as a two-wire to two-wire adaptor (e.g. RTS to TecPro) by interconnecting both two-wire interfaces at the four-wire level. This is achieved by connecting converter A’s four-wire output to converter B’s four-wire input. Likewise, converter B’s four-wire output is connected to converter A’s four-wire input.
When used as a dual two-wire to four-wire interface the SSA324 carries two voice channels. This is reduced to a single voice channel when operating as a two-wire to two-wire interface.
To increase common-mode isolation between two-wire and four-wire systems, optional transformers may be fitted to all active inputs and outputs.
Nulling of the return two-wire signal can be carried out by either a voice test or a test tone selected by an internal jumper. There are three null adjustments associated with each two-wire port. These are centred around 3kHz, 1kHz and 300Hz. Nulling may be re-adjusted at any time to compensate for changes to the intercom line caused by adding or removing stations.
If full-duplex operation is not possible due to acoustic feedback, introducing a small amount of ducking can clean up the signal. This should not be overdone.
Systems from different manufacturers operate at different levels. Both A and B interfaces have volume controls to adjust the audio signal going to and from two-wire.
Rear-panel connections comprise a pair of 3-pin XLR connectors for two-wire interconnections, eight rapid-access terminals for making speedy four-wire interconnections in the field, and one 25-pin D-sub connector duplicating the functions of the rapid connection terminals together with additional features.