m908 User Manual, Rev. G
Sample Rate Status
Sample Rate
Display
System Clock Status Audio Source
Condition
User Action Required
44.1kHz –
192kHz
(White)
Current Sample Rate
m908 plays audio
None
--- (White)
With analog only input
active: invalid system
samplerate
With digital input active:
input signal unlocked
m908 cannot play audio
and outputs are muted
Analog input(s): set system
clocksource to a valid clock
Digital input(s): connect a
valid source"
fs mismatch
(Flashing
Red)
Digital input has signals
at multiple sample rates
m908 cannot play audio
and outputs are muted
All digital signals in a user
defined input must be
synchronous
5.22 Word Clock In and Out
The m908 can accept a standard 5V/75Ω word clock signal from an external clock generating
unit. This might be a stand-alone master clock source or the word clock output from your digital
audio workstation interface. The m908 locks to the incoming word clock with an ultra low jitter
s-Lock PLL. The PLL has a fast lock mode which rapidly acquires lock and then switches to a
high jitter rejection mode with a loop bandwidth of 0.5Hz. This provides exceptional jitter
rejection for the ADC and DAC sample clocks. In the event of a dropout or loss of incoming
word clock signal, the intelligent PLL will remain at the last known valid frequency. When the
signal is restored the PLL will smoothly re-acquire lock.
The word clock output allows the user to synchronize other digital audio equipment to the
m908. When the menu setting
clock output
is set to <clock in> this connector output is a copy of
the signal on the Word Clock IN jack. This mode is useful for "daisy chaining" multiple devices
together in a system. When
clock output
is set to <system clock> this connector outputs a copy
of the m908 system word clock. The Word Clock output jack is buffered and is designed to drive
a 75Ω line at 5V.
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