ATI DDA208-BNC User Manual

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DDA-208

SERIES 2

HIGH RESOLUTION DUAL 1x4

DIGITAL AUDIO DISTRIBUTION

AMPLIFIERS

OPERATING AND MAINTENANCE MANUAL

© Copyright 2013, ATI Audio

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DESCRIPTION

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DDA208 Series 2 1x4 Dual Digital Audio Distribution Amplifiers are designed to
regenerate, isolate and distribute digital audio data formatted in accordance with
specifications AES3-1992 and IEC 958. This is commonly called AES/EBU
formatting or AES3.

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DDA208 Series 2 units inputs feed AES audio to eight separate outputs. Internal
jumpers select either re-clocking or non-reclocking of the input signal. In most
cases, re- clocking is preferred, as this feature improves the integrity of weak or
distorted input signals. Re-clocking may be switched off to allow distribution of
AES sync signals, Dolby E encoded AES signals, or other signals that should
not be re- clocked.

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DDA208 Series 2 units work with AES signals that contain sample rates from 27
through 192kHz and16-bit through 24-bit density, thus permitting very high
resolution signals to be distributed.

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The Model DDA208-XLR uses XLR connectors and operates from and drives a
110-ohm balanced shielded twisted pair distribution system per AES3-1992.

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The Model DDA208-BNC uses BNC connectors and operates from and drives
single-ended 75-ohm coaxial cable per AES-3id-1995 and is designed
to integrate easily into video facilities.

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S/PDIF (consumer) formatted digital audio data differs primarily in the use of
consumer type "RCA" audio connectors in an unbalanced 75 ohm system and
can be handled by a DDA208-BNC with use of an RCA-to-BNC input cable.

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Input Loop-through connection is provided to permit multiple units to be stacked,
or to insert the DDA208 into your digital workflow. Switchable line termination is
provided via Internal jumpers. Standard practice dictates that the last AES input
be terminated; therefore, if you are not using the loop-through feature, Input
Termination should be switched ON.

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FEATURES

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• Accepts sample rates from 27 to 192kHz

• Switchable re-clocking regenerates stable data before distribution

• Loop thru transformer balanced and isolated inputs

• Switchable input termination

• Individual, transformer balanced and isolated 110-ohm XLR outputs (XLR only)

• Individual isolated 75-ohm BNC outputs (BNC only)

• Eight outputs

• Quiet, internal power supply

• AC Input 100-250 VAC 50/60 Hz, 25W Maximum

• Attractive and rugged 1RU package

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DESCRIPTION

INPUTS

Incoming AES/EBU formatted digital audio data is selected by the internal
jumpers and applied to the input transformer. Both XLR and BNC inputs are
balanced and DC isolated from ground. Input termination resistors at
75 ohms for BNC inputs or 110 ohms for XLR inputs can be switched in or out of
the circuit with the internal jumpers. Inputs should always be terminated unless
they are looped thru to another device or DDA input. The last device or input
should always terminate the line.

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RECEIVERS

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When input re-clocking is enabled, the equalized AES/EBU data stream is
applied to the receiver circuit, which recovers the clock and synchronization
signals and separates the audio and digital data. The audio data may be 16 to 24
bits at sample rates from 27 to 192 kHz.

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Frame sync (FSYNC), Serial Clock (SCK), Serial audio data (SDATA), Channel
status (C), User channel data (U), and data validity information (VERF) are
passed directly to the transmitter section for reformatting into the output data
stream. VERF is an OR’ing of the validity information from the incoming data (V)
with an internal error flag (ERF) that detects serious transmission errors such as
parity errors, bi-phase coding violations and an out-of-lock PLL receiver. VERF
then becomes the transmitted validity bit (V) and can be used by downstream
error correction devices to interpolate through errors.

TRANSMITTERS

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The Frame sync (FSYNC), Serial Clock (SCK), Serial audio data (SDATA), Channel
status (C), User channel data (U), and data Validity information (VERF) are passed
directly to the transmitters for reformatting into the AES/EBU output data stream. The
transmitters are capable of operation from 27 to 192 kHz equivalent sample rates. The
transmitters operate in a transparent mode, which allows the transmitter block
structure (Channel Status, User and Validity bits) to be slaved to the block structure of
the receiver. In the transparent mode the propagation delay of data are less than 25
nanoseconds even at the lowest sample rate.

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OUTPUT DRIVERS

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DDA208-XLR units are equipped with balanced, 110-ohm, transformer coupled
outputs and XLR type connectors. DDA208-BNC units use the alternative 75­ohm unbalanced outputs to BNC coax connectors. The XLR outputs are in full
compliance with specification AES3-1992 and the BNC outputs are in
accordance with the recommendations of AES-3id-1995. XLR outputs are
transformer coupled for ground isolation.