Housed in red-anodised aluminium rack-mounting cases these Sonifex silence detectors are used to monitor an output feed and in the event of the signal going 'quiet' after a given period, switch through an alternative audio signal. This signal could be recorded material, or an alternative recorded program. While the obvious application is in radio broadcasting, the units are equally capable in any situation where it is important that an outgoing signal is maintained at all times.
Sonifex RB-SD1 has two stereo inputs, designated A and B, which are assigned as the Main or Aux signal using a switch on the front-panel. The front panel has four LEDs indicate programme presence and alarm conditions for each channel of the two sources. When the signal on any input remains below the threshold level for a preset period of time, the associated front panel alarm LED illuminates and if the audio routing feature is enabled, the output is switched to the Aux signal. Three further indicators are used to show the status of the Source, Mode and Restore functions, adjacent to push switches for setting these functions.
For mono sources, the alarm can be set to trigger on the loss of signal level on either input channel, and for stereo sources the alarm triggers when both left and right inputs fail. In manual restore mode, the alarm must be reset from the front panel or remotely. If the automatic restore mode is chosen, the main source will be routed to the output two seconds after the programme returns.
The unit is equipped for remote operation; the alarm outputs from both Main and Aux detectors and the front-panel switch functions available. A start signal is also available to activate an external device, such as a tape or CD player, when the alarm triggers. The audio inputs and outputs are designed for balanced line level connections. However, in consumer mode, Input B accepts unbalanced equipment and applies 12 dB of make-up gain.
The rear panel has two pairs of female 3-pin XLR connectors for inputs A and B, and one pair of 3-pin XLR outputs. In the un-powered state, input connectors ‘A’ are routed to the output. There are two 16-position rotary switches; silence detect level is adjustable between -60dBu and -15dBu in 3dBu steps and silence interval can also be adjusted between 2 and 30 seconds in 2 second steps. An additional maximum delay setting of 125 seconds is available, which can also activated remotely to minimise false alarms on quiet programme passages. A 15-pin male D-sub connector provides connections for the remote controls.
Input: +28dBu maximum, 0dBu nominal, greater than100k ohm, balanced. Gain: 0dB, +8dB for input B in consumer mode. Response: 20Hz to 20kHz +/-0.1dB. Distortion: 0.05% THD, 1kHz, +8dBu output. Noise: -87dB, unity gain, +8dBu output. Output impedance: As input source, or less than 50ohms for Input B in consumer mode. Power source: 110-120V or 220-240V AC 6W maximum. Dimensions: 480(w) x 108(d) x 42(h) mm. Weight: 1.4kg.
Included accessories: Handbook, AC power cordset with plug.
Optional accessories: The RB-RK3 rear panel rack kit.
Ordering note: The RB-SD1 can be supplied, to special order, pre-programmed at the factory for specific applications. Please contact Technical Support for assistance.
The RB-DSD1 works in a similar way to the Sonifex RB-SD1 analogue silence detection unit, but has AES/EBU, S/PDIF and TOSlink inputs and outputs instead of analogue inputs and output respectively. All three different types of output can be used simultaneously. Sample-rate converters on each input provide for sources of different sample-rates to be mixed while the output sample-rate is defined independently. The digital audio output can be synchronised to either input, an AES/EBU reference input, a TTL word-clock BNC input or an analogue or SDI video feed if used with optional boards. The output can also be synchronised to an on-board master clock, with a selectable frame-rate. In the case of power failure AES and S/PDIF signal inputs are routed to outputs, essential for environments such as transmitter sites.
In the synchronisation 'Master' mode the output sample-rate is simply set by, and locked to, the internal on-board clock generator. No sync signal is used or required. In 'Auto- sync' mode output sample-rate follows the selected sync input. When the sync signal is not present the output sample-rate will be set by, and locked to, the internal on-board clock generator at the selected output frequency. In 'Auto Lock' mode no output will be generated until lock is achieved with a sync signal. The output sample-rate then follows the sync input. If the sync signal is removed then the output sample-rate will be set by, and locked to, the internal on-board clock generator at the closest frequency available to the previous sync input. In 'Slave' mode the output sample-rate follows the sync input. When the sync signal is not present the digital output is turned off.
The front panel has four momentary switches each with an arc of LED indicators. The first 'MAIN' switch selects which input source is used for the main input. Three LEDs above a backlit button illustrate which source is selected. There are also green and red LEDs, one of each for both left and right channels to show the programme and alarm state of the input. Programme LEDs will be illuminated if the level is above the current silence threshold. If the input is in an alarmed state, red alarm LEDs will illuminate. A 'RESTORE' button is used for restoring the main source signal when the unit is operating in manual mode. This can be remotely controlled using the remotes connector.
A small panel may be unscrewed to reveal three banks of miniature (DIP) switches to adjust the duration over which a silence is detected before alarming from the default 30 seconds to 2-252 seconds in two second intervals. A second bank adjusts the level below which silence detection occurs and can be varied from -39dBFS to -84dBFS in 3dB steps. A third bank defines switching when incoming source goes silent. When in stereo mode, if one channel goes quiet the unit will switch, and requires both channels to be present before it switches back. In mono mode the unit will only switch when both channels go quiet, and requires only one channel to be present before the unit switches back.
The rear panel has two groups of connectors, one for inputs one for outputs. Each has two XLR connectors for balanced AES/EBU digital connections, two RCA (phono) connectors for S/PDIF and two TOSlink optical connectors, one of each for stereo channels one and two. An XLR provides an input for AES/EBU sync and a BNC for word-clock. The serial port and 'remotes' connectors are 9-pin and 15-pin D-sub types, respectively. Power is connected by an IEC inlet. A miniature (DIP) switch-bank provides switching between ‘master’, ‘restore’, ‘remote start’, ‘channel loss’ and ‘sync loss’ modes.
Distortion and Noise: Better than -137dB THD + N at 1kHz, ref 0dB FS. Sample frequencies: 32, 44.1, 48, 88.2, 96, 176.4 or 192kHz. Bit-depth: Up to and including 24-bit. Power source: 85-264V AC, 47- 63Hz, 10W maximum. Dimensions (WxDxH): 480 x 108 x 42mm, 1U. Weight: 1.4kg.
Included accessories: Manual, AC power cable.
Optional accessories: RB-RK3 Rear rack panel kit, RB-SYA, RB-SYD
These sync boards, compatible with RB-DSD1, RB-SC2, RB-TGHDX and RB-TGHD8 mount inside the case, with a BNC connector protruding through a pre-punched aperture. They can be used to synchronise the outputs to a 48kHz sample rate.
RB-SYA analogue sync board will accept a composite signal of NTSC (525), PAL (625) and SECAM (625) signals covered by SMPTE-170-M (NTSC) and ITU-R BT.470-6 (PAL and SECAM).
RB-SYD digital video sync board will accept 270Mbps SD-SDI and HD-SDI signals covered by SMPTE-259-M-C (SD) and SMPTE-292M (HD).