Drawmer DC2496 High Resolution A/D Converter - Manual (Page 18)

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CHAPTER 4
HELPFULL HINTS
Recording Hi-Resolution ‘Bit splitting’ tracks on a
Digital Tape Recorder (ADAT or TDIF)
When recording Triple (48k) or Hex (96k) Hi-Resolution tracks to tape the
SRC (upper) AES & SPDIF digital outputs will monitor tracks 7/8 @ 20 or
16bit resolution depending on the rear panel push switch.
When TDIF ‘D’ plug is inserted the DC2496 BNC Word Clock output will be
phase shifted by 90 degrees at a rated 44.1k @ 88.2k and 48k @ 96khz.
This is the clock for TDIF Word Sync.
When using A/D, ADAT or TDIF as the input signal and SAMPLE RATE is
set to EXT with AES/SPDIF then the DC2496 will get its EXT word clock
from the AES digital input (XLR socket), not the SPDIF digital input socket.
The main (lower) SPDIF and AES output sockets both support 88.1 and
96K 24bit signals if selected on the front panel. The EXT SPDIF word clock
input is only available when SPDIF input signal is also selected.
The Sample Rate Converted AES & SPDIF output sockets are rounded to
16/20bits and HF dither added regardless of front panel settings according
to the rear panel switch.
The ‘Setup tone’ frequency will only be accurate to a few percent of its
correct value when an EXT clock source is used.
The Rear panel ‘Green audio signals OK’ LEDs are lit when the PLL is
locked and signals are output.
ADAT and TDIF track outputs will always be at 44.12/48Khz even if A/D or
Digital input is at 88.2 or 96K
There are two Hi-Resolution recording modes:
Triple (3) track 24bit 44.1 or 48Khz on either or both tracks 123 or 456, or,
Hex (6) track 24bit 88.2 or 96Khz on tracks 123456.
Both triple and hex track modes also have a stereo backup 16bit 44.1 or
48k recording on tracks 7/8
When recording a 48/44.1K Hi-Res triple track it is prefferable to use tracks
4,5,6.
If tracks 123 only are recorded then there noise will be heard when
monitoring tracks 5,6. This is correct and is the ‘Remainder’ track of the Hi-
Res signal.
If track triple 4,5,6 is recorded or both sets of Triple tracks then this noise
will not be heard.
Special Digital Tape Recorder (ADAT or TDIF) Play
cases:
When replaying a normal ADAT or TDIF recording, all 8 tracks will be
directly copied to the 8 TDIF and ADAT output tracks.
Limiter, Gain, Word resolution, dither etc will not modify the 8 track signals.
The Main digital output will have Gain, Limit etc. and will monitor the
selected replay track LEDs.
The 48/44.1Khz SRC digital output will exactly monitor the selected replay
track LEDs (without Gain, Limiter etc).
When replaying a Hi resolution triple or hex track recording (made when
both 24 and 16 bit WORD RESOLUTION LEDs are lit) the Sample Rate
Convertor digital AES/SPDIF, the Main AES/SPDIF digital output and TDIF
and ADAt track outputs 7/8 will replay the stereo signal from the tracks
shown by the REPLAY TRACK LEDs. Gain, limiter, Bit rounding & dither can
all be applied.
The TDIF and ADAT output tracks 1 thru 6 will be an exact bit copy of the
triple or hex track Hi-res recording.
For best results when reducing a 96K 24bit recording to 44.1 @ 16 bits
leave the front panel LED set to 24bits and reduce the signal to 16bits @
44.1Khz on the SRC rear panel grey push switches.
The DC2496 cannot record or play normal stereo signals @ 96k to ADAT or
TDIF. You must select the WORD RESOLUTION as 2 LED (16 and 24) bit
spliting mode and Sample Rate as 44.1/48K.
Up to 4 x DC2496 can be used to simultanious record 48K 24bit signals (if
the recorder alows) to TDIF using a special splitter lead. The Word Clock
must be EXT TDIF on the DC2496’s with the TDIF machine providing the
Word Clock. This cannot be done using ADAT light pipe
Several DC2496 units can be synchronised to sample accuracy (better
than 0.2uS) by setting the master unit SAMPLE RATE to Internal clock 96/
88.2/48/44.1 FS then setting the other units as EXT BNC word clock
slaves.
+D=FJAH 4 SPECIAL OPERATION NOTES