ENGLISH
6
To access the digital signals from the 9-pin D-type output
connectors, the A/D card must be purchased with either an
AES or SPDIF D-Type conversion cable as follows:
AES cable: 9-pin D-type to 4 male XLR connectors.
SPDIF cable: 9-pin D-type to 4 male RCA (phono)
connectors.
Note: cables need to be purchased separately. Since there
are two different cable options - XLR for AES and
RCA/phono for SPDIF - these are not included with the
A/D converter options. Focusrite cables may be purchased
from your local dealer. If you experience difficulty in
obtaining these cables, contact your local distributor as
listed in the back of this manual.
The AES/SPDIF Connector Configuration
There are two AES connectors which can be configured as
follows:
AES/SPDIF 9-pin D-type
The connector labelled AES/SPDIF can be configured either
as an AES or an SPDIF dedicated output using the
AES/SPDIF switch next to it. When operating the connector
in AES mode an AES cable is required. When operating in
SPDIF mode the SPDIF RCA cable should be used, which
automatically sets the output stream to consumer mode.
AES 9-pin D-type
The second AES connector labelled AES always transmits in
AES-only mode regardless of the position of the AES/SPDIF
switch. The switch between the two 9-pin D-type
connectors selects the AES output between ‘1 wire’ and ‘2
wire’ mode as follows:
1 Wire Mode
Selected with the switch in the ‘out’ position. Both AES
connectors transmit 8 channels of AES data simultaneously
for all sample frequencies from 44.1 to 192kHz.
2 Wire mode
Selected with the switch in the ‘in’ position. Each AES
connector transmits 4 channels of AES data separately for
sample frequencies from 96kHz to 192kHz.
The reason for the two modes is that older equipment with
96kHz and 192kHz AES inputs can only receive speeds up
to 192kHz by using both digital channels of a single AES
connection (known as ‘2 wire’). Therefore one AES channel
can only send a single channel of digital data, and thus the 9-
pin D-type is switched from transmitting 8 channels of data
to sending 4 channels of data. Therefore to send all 8
channels from the ISA 428 in this mode requires two AES
connectors: one sending channels 1 to 4 (AES/SPDIF
connector) and the other sending channels 5 to 8 (AES-only
connector). Having this switch makes the ISA 428 useable
with both old and new equipment.
Word Clock In and Out
The internal ADC can be synchronised to an external word
clock. By pressing the front panel Ext switch, the
synchronisation mode can be switched between standard
external word clock and 256X external word clock. Both
types of external word clock should be connected to the
ISA 428 ADC card at the Word Clock In BNC connector.
The Word Clock Out BNC connector either regenerates
the external word clock connected at the Word Clock In
BNC connector, or transmits the internal sample frequency
of the ADC card. Where the ISA 428 is being used as a
slave device within a larger digital system, the Word Clock
Out BNC connector can be used to pass on the external
word clock signal to the next device. When the unit is not
slaved to another device and is in internal clock mode, the
Word Clock Out BNC connector outputs the sample
frequency selected on the ISA 428 front panel.
Digital Output Front Panel Controls
Clock Select
Pressing this switch allows the user to select between
sample frequencies of 44.1kHz, 48kHz, 88.2kHz, 96kHz,
176.4kHz, and 192kHz
Bit Depth Select
Selectable between 24, 20 and 16 bits.
Ext Select
Pressing EXT allows the ISA 428 to be slaved to an external
word clock source. Selecting 256X allows the ISA 428 to be
slaved to an external clock running at 256 times faster than
the sample frequency and enables connection to systems
such as the Digidesign 'Superclock' or other 256 slave clock
devices.
Lock LED
When lit, LOCK indicates that the unit is synchronised to
an external clock.
