© 2004 Wohler Technologies Inc. ALL rights reserved
20
AMP2-SDA/AVU
and
AMP2-SDA/APP
User Manual P/N
821576
Rev-
A
Section 3:
Technical Information
AES to Analog Converter Module PCB (919117) Description
There are four primary and three ancillary sections comprising the
919117
AES
digital to
analog
converter:
1) Input source selection.
2) Audio data extraction.
3) Digital to analog conversion.
4) Analog buffer/output amplifiers.
5) Power suppy, Reset, and Error indication.
Input Source Selection (IC13)
Each of the two selectable signal inputs are transformer-coupled to the inputs of a one-of-two active buffer/switch (IC13). The
output of this switch is applied to the receiver stage of the AES receiver/unframer.
Audio Data Extraction (IC11)
"Header" and ancillary data are removed from the recovered input datastream, yielding a datastream having only alternating left/right
channel audio data which is output on pin 26 of IC11.
Digital to Analog Conversion (IC10)
The "pure" audio datastream, along with a data clock and a channel ID (left/right) clock, are applied to a 20 bit two channel D to A
converter (IC10), where the datastream is converted into left and right analog outputs.
Analog buffer (IC4) / Output Amplifiers (IC8, IC9)
Buffer/amps provide balanced left and right channel outputs as well as single ended outputs. Gain calibration, the analog level which
corresponds to a given digital value, is settable via a DIP switch. The default factory setting is 20 dB below "full code" (digital zero)
to equal +4 dbu (0.775V). The other three settings possible are for -18 dBfs = 0 dBu, -9 dBfs = +6 dBu, and -20 dBfs = +8 dBu.
See page 12 for DIP switch location and settings.
Power Supply
The 24V rail internal to the rest of the unit is converted to +5V for digital portions of the 919117 PCB by switching regulator IC12.
Error Indication
The AES status LED is a bicolor LED (Red/Green). It is green as long as a valid digital data strean is being received. The 8412
receiver is capable of distinguishing two types of error conditions: 1) Faulty data; data identified by the sending device (possibly
invalid), or 2) Faulty reception; errors in reception of data or no data stream at all. The red LED indication may be set to occur for
only faulty reception (section 1 closed) or with either faulty data OR faulty reception (section 1 open). See
Item C
, page
12
for
more information regarding this setting.
919117 Specifications
D to A gain calibration,
(dB = dBFS):
AES sampling rate:
D to A converter:
Converted analog out:
(S/N):
Converted analog out:
(THD):
AES Termination:
+8 = -20, +4 = -20, +6 = -9,
0 = -18 (DIP selectable)
32-48 KHz, auto-select
24-bit low jitter
>90 dB
< 0.008%
Removable (DIP select)
