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9. Special Functions
9.1 Bit Split
Especially digital tape recorders are often limited to 16 bit resolution. To use the complete dy-
namic range of the ADI-8 PRO with such devices the functions BIT SPLIT and COMBINE
were integrated. This technique is a simple but effective solution, differently used by several
manufacturers.
The method used in the ADI-8 PRO is compatible to the one used by Yamaha in their digi-
tal mixing desk 02R, so the ADI-8 PRO can be used directly in 24 bit operation with this
desk. Additional the COPY MODE (see chapter 8.2 Copy Mode) allows an operation of BIT
SPLIT and COMBINE in digital domain. This allows to use the ADAT inputs of the 02R with full
24 bit resolution (normally limited to 20 bit).
BIT SPLIT divides the 24 bit signal into a 16 bit and an 8 bit signal. When recording on 16 bit
machines two tracks are required for each channel, an 8 track machine will record 4 channels.
To transmit all 8 channels of the ADI-8 PRO two digital interfaces (16 tracks) are provided
and have to be used.
On the rear of the ADI-8 PRO two ports of each TDIF and ADAT format named MAIN and
AUX can be found.
When BIT SPLIT is active the analog ins are processed to the digital outs as shown below:
Input
1
Output
1/5
Port
MAIN
As long as not more than the first 4 channels are used only the MAIN output is necessary. It
makes no sense to connect AUX as it carries no data. When using inputs 5-8 the AUX output
also has to be used and carries the data of inputs 5-8.
9.2 Combine
COMBINE is the reverse function of BIT SPLIT, putting split signals back together according to
the upper table. Again: As long as not more than the first 4 channels are used only the MAIN
input is necessary. The AUX input has to be used to receive channels 5-8.
As COMBINE is fed from digital inputs a function to verify lock and synchronicity is required.
The lock state of the MAIN input is indicated as usual by the LEDs of the Clock DA section. The
input AUX has its own lock/sync LED at the key COMBINE. This LED operates in a slightly
different way as it indicates both Lock and Sync state.
As long as no signal is found at the AUX input the SYNC LED will be off. When a valid sig-
nal is fed the LED begins to flash (lock state). When the data received is synchronous to
the data at the input MAIN the LED will stay lit (lock+sync state). This securely indicates
and prevents audio errors in COMBINE mode.
2
3
2/6
3/7
MAIN
MAIN
MAIN
User's Guide ADI-8 PRO © RME
4
5
4/8
1/5
2/6
AUX
AUX
6
7
8
3/7
4/8
AUX
AUX
15
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