Mutec MC-3+ Smart Clock USB Operating Manual page 22

Operation
«) and will output the converted PCM signal of the DSD stream. Both lock indicators in the »STATUS« section are illumi-
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nated – the top LED indicates the lock to the DSD signal, while the bottom LED confirms synchronization to the external clock
reference.
Two re-clocking modes are available: one based on the internal ultra-low jitter clock oscillator (»RE-CLK« & »INTERN«) and the
other locked to an externally applied clock reference (»RE-CLK« & »EXTERN«).
»INTERN« & »RE-CLK«
The »INTERN« and »RE-CLK« LEDs will light up when »RE-CLK« mode is selected, indicating that the re-clocking mode based
on the internal clock oscillator is now active. As a factory default, »USB-PCM« and »USB-DSD/DoP« are selected as the first
available audio reference in the »REFERENCE« menu (the first three LEDs in the column are illuminated). Press the menu key
once and you're entering the »REFERENCE« menu. Toggle the »SELECT« key to select one of the four available audio referen-
ces: USB (PCM & DSD/DoP), AES3/11, S/P-DIF op, S/P-DIF bnc. This will now be re-clocked with the internal ultra-low jitter clock
signal, format-converted, and passed on to all audio outputs with the same sampling rate simultaneously.
Attention
Special use case: DSD/DoP as audio reference
When selecting »USB-PCM« and »USB-DSD/DoP« as audio reference in »RE-CLK« mode, the MC-3+USB will convert a DSD or
DoP signal to a PCM audio signal in real time. The converted PCM signal will then processed by the re-clocking algorithm and
will be available at the different audio outputs. The original DSD and DoP streams will not be passed over to the outputs.
Furthermore, a sampling rate has to be selected for the PCM audio outputs in the »CLOCK
« menu by pressing the »MENU« key where you can choose between 44.1, 88.2, and 176.4 kHz. The same applies when the
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MC-3+USB is operating in the externally referenced re-clocking mode (see below).
»EXTERN« & »RE-CLK«
This is a very unique feature that is only available in your MC-3+ Smart Clock USB! After selecting the first re-clocking mode,
press the »SELECT« key once again and the »EXTERN« and »RE-CLK« will light up to indicate that re-clocking based on an
externally applied clock reference is now active. Per default setting, »USB-PCM« and »USB-DSD/DoP« are selected as the first
available audio reference (the first three LEDs in the column are illuminated). Press the »MENU« key once to access the »RE-
FERENCE« menu and toggle the »SELECT« key to choose one of the four available audio references: USB (PCM & DSD/DoP),
AES3/11, S/P-DIF op, S/P-DIF bnc.
Please note: the system will however expect an external re-clocking reference at the »WCLK & 1-10M IN« BNC input on the
rear in this mode. If this reference is not provided, the re-clocking process will not be active. Possible re-clocking references are:
Word Clock 32.0 kHz – 192.0 kHz
1.0, 2.5, 5.0, 10.0 MHz
If both a valid audio and a re-clocking reference have been applied, the blue lock LEDs »MAIN REF« and »RE-CLK REF« in the
»STATUS« section will light up and the re-clocking process will be started. The sampling rate of the incoming digital audio
signal will be displayed in the »CLOCK
»CLOCK « menu as described in the »Selecting Clock Multipliers« section.
MULTIPLIERS
Selecting one of these externally referenced re-clocking options enables re-clocking a digital audio signal with an external
clock reference of a peripheral master clock generator. In all cases, the converted digital audio and Word Clock signals will have
the same sampling rate as the digital audio source. However, there is no phase lock between input and output signals in this
mode!
Attention
Using external clock references for audio re-clocking
If you'd like to use a Word Clock or 10.0 MHz clock reference for the externally referenced re-clocking, you should make sure
that particularly the phase noise near the carrier frequency (1-100 Hz range from the carrier frequency at 10.0 MHz) is very
low. Because of the extremely low noise signal processing of the MC-3+USB, there is a risk of audibly worse signal performan-
ce if the externally applied clock reference is too noisy.
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« section of the front panel. The Word Clock output signals can be multiplied using the
IN
« menu. Switch to the »CLOCK
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