®
I N C .
P A C I F I C
M I C R O S O N I C S
26
Setup & Operation
Model Two HDCD
®
User’s Manual
Rev. C - January 2002
Using the Model Two as a Master Word Clock Generator
In all AD and DD operating modes at all sampling rates, the Model Two can be configured
to be a master word clock generator. This mode of operation is highly recommended be-
cause it allows the Model Two’s A/D and D/A converters to be clocked directly by the Model
Two’s precision internal clock, instead of by the digital input signal, when the devices that
are connected to the Model Two’s digital signal inputs and outputs, such as recorders,
transports, DAW’s, etc. are locked to the Model Two’s word clock output. This greatly
reduces D/A conversion distortion caused by digital input signal time base jitter. Of course,
a D/A converter can only be locked to a clock seperate from the digital signal being
monitored if the clock is synchronous with the signal!
Setup for AD and DD Operating Modes
For AD Operating Modes:
1.
From the Operating Menu, select the desired Base Sample Rate (SETUP/MODE/44.1_X
or 48_X) and Preset Configuration (SETUP/PRESETS).
2.
From the Operating Menu, select (SETUP/INPUT/REFCLK/MASTER).
3.
From the Operating Menu, select (SETUP/INPUT/MON_REF/A/D_REF).
4.
Connect a 75
Ω
coaxial cable from the Model Two’s Word Clock Ref BNC connector to
the 75
Ω
external word clock or word sync input BNC connector on the component
connected to the Model Two’s digital signal inputs and outputs, or to a 75
Ω
word
clock distribution amplifier.
For DD Operating Modes:
1.
From the Operating Menu, select the desired Base Sample Rate (SETUP/MODE/44.1_X
or 48_X) and Preset Configuration (SETUP/PRESETS).
2.
From the Operating Menu, select (SETUP/INPUT/REF_CLK/MASTER).
3.
Connect a 75
Ω
coaxial cable from the Model Two’s Word Clock Ref BNC connector to
the 75
Ω
external word clock or word sync input BNC connector on the component
connected to the Model Two’s digital signal inputs and outputs, or to a 75
Ω
word
clock distribution amplifier.
Setup for AD and DD Multichannel Operation:
One Model Two is configured as described above to be the master word clock generator.
Additional Model Twos are configured to be “slaves” as described on page 27. Their Word
Clock Ref BNC connectors automatically switch to become high impedance inputs and the
75
Ω
word clock output of the master Model Two is looped through them using the sup-
plied 75
Ω
coaxial BNC cables and BNC “T” connectors and is then terminated by the 75
Ω
word clock or word sync input of the device connected to the Model Twos’ digital signal
inputs and outputs or by a 75
Ω
word clock distribution amplifier.
