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Menu 030: Timecode Muting Options
Some console automation systems and MIDI sequencers have an adverse reaction to incoming
SMPTE time code or MIDI Time Code at a non-standard speed. With version 2.0, Menu 030 offers
different “muting” options when shuttling at speeds other than playspeed.
• “Normal”-operates as it always has. MX-2424 will transmit time code when it is shuttling at fast
and slow speeds.
• “Mute High Speed”-MX-2424 will mute the time code outputs when shuttling at high speed, but
will still output code when shuttling at a low speed.
• “Mute Low Speed”-MX-2424 will mute the time code outputs when shuttling at low speed, but
will still output code when shuttling at a high speed.
• “Mute High and Low”-MX-2424 will mute the time code outputs at low and high speeds.
To complement these muting options, the MX-2424 will now transmit the MIDI Time Code Full
Message when the normal MTC Quarter Frame message stream has otherwise been muted. This will
allow MIDI controllers to track the current MX position at all times. The MTC Full Message is by
definition for display purposes only, and an MTC transmitter (here the MX-2424) is not considered to
be "running" unless the standard MTC Quarter Frame messages are being issued. Full Messages will
be transmitted at a maximum rate of one per 5 time code frame periods, and will not be sent if the
time code position has not changed.
For Example:
If set to mute time code, the MX-2424 will still send MTC positional information that
can be read by a mixer’s time code display. However, the MX-2424 will not send MTC information
that the mixer’s automation would chase. This would also be true of a MIDI sequencer.
Menu 060: Word->AES Phase
If you use AES/EBU as an input source and ALSO use Word Clock for your clock source, there
is now an option to switch the polarity of the incoming Word Clock.
There are currently no standards which define the phase relationship between an AES/EBU
digital audio signal and a standard TTL word clock. This can cause clock discrepancies between
various digital audio devices.
To reduce this possibility, the MX-2424 can now "flip" the polarity of its word clock 180
egrees.
d
e MX-2424 has always used. “Low-High” describes the word clock polarity that th
“High-Low” describes the "phase-inverted" method.
[In technical terms: the “Low-High” word clock has its falling edge aligned with the AES3 "X"
reamble, while the “High-Low” form has its rising edge so aligned.]
p
If the TDIF option is installed, then the TDIF bus phase will "flip" along with the word
ignals, thus preserving the correct phase relationship between word clock and TDIF.
clock
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system are
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If you experience trouble locking the MX-2424's clock to other gear, experimentation with Men
060 can often help. This problem is most likely to occur when some devices in the
locking to word clock, while others are locking to an AES/EBU or S/PDIF input.