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dCS 904 User Manual Manual for Software Version 1.5x and 1.36
dCS Ltd June 2000
Manual part no: DOC135904 iss 2B2
Page 12
135904ma2b2.pdf file available from website
Contact
dCS
on + 44 1799 531 999 email to: more@dcsltd.co.uk
(inside the UK replace + 44 with 0) web site: www.dcsltd.co.uk
Front Panel
A to D Converter
dCS 904
Data Conversion Systems
2
4
192
dC S
BIT
kHz
Sample
Rate
Multiplier Mute
Word
Length
Noise
Shaping
Overload
Level
Overload
ADC/
Data
Master Slave
Output
Format
MENU
Step Set
kS/s
Sample Rate
DSD
Direct Stream Digital
Figure 2 – Front Panel
The dCS 904 uses a combination of front panel buttons for frequently changed
functions and a step through menu for features you might set and forget.
Sample Rate -
Multiplier -
The 2 buttons on the left side of the front panel select the sample rate. Press the
Sample Rate button repeatedly to cycle through the sample rates in the order:
192 ... 176.4 ... 96 ... 88.2 ... 48 ... 44.1 ... 32 ... 192 ... etc.
To step through more quickly, press the Multiplier button repeatedly to cycle
through in one of the following sequences, depending on the starting sample
rate:
48 ... 96 ... 192 ... 48 ... 96 ... 192 ... etc.
44.1 … 88.2 ... 176.4 ... 44.1 ... 88.2 ... 176.4 ... etc.
To change sample rates quickly, use the two buttons together. For example, to
change from 176.4 kS/s to 192 kS/s press Sample Rate once then Multiplier
once. Do not press the buttons too fast as a delay is built in to the software. The
sample rate selected is shown on the LED display in the centre of the panel.
Mute -
The Mute button forces a mute, in addition to the automatic ones. The digital
outputs are automatically muted at power up and when the sample rate is
changed or the unit is locking to a reference source. A forced mute is indicated
by the mute LED (above the mute switch) lighting up. In normal use, pressing
the Mute button mutes the digital outputs and lights the mute LED. Pressing the
Mute button again unmutes the ADC, as long as no automatic mute is being
applied.
Word Length -
Noise Shaping Menu
Back
The AES/EBU format accommodates data up to 24 bits. If a shorter word is
needed and the extra bits are just ignored, the result is typical “digital” sound
due to the abrupt chopping off of the low level signal information.
To avoid this, the dCS 904 allows proper truncation of the data and uses Noise
Shaping to maintain low level performance. See the section on “Word Length
Reduction” on page 64 for some background on this. If you do use word length
truncation, make sure that Noise Shaping is not set to OFF without realising it.