MOTU Audio Express Guide de l'utilisateur télécharger pdf (Page 71)

CUEMIX FX

outside the critical frequency range of the

instrument being recorded, you can avoid phase

problems among the mic signals.

Tun i ng PA sys te ms

The Phase Analysis window can also be used to

troubleshoot and tune PAs and sound

reinforcement systems by placing microphones in

strategic locations, comparing the two signals in

the Phase Analysis grid and looking for phase

issues at various locations.

Summing to mono

The Phase Analysis window is ideal for checking

stereo audio that needs to be summed to mono.

The Phase Analysis lets you see what frequencies

will be canceled out when summed.

In the rectangular view, any lines in the signal that

touch the +1.0 or -1.0 vertical lines in the grid will

be canceled out at the frequency where they touch,

when the signal is summed to mono.

In the polar view, any signal that falls on the

negative y axis (below zero) in polar view will be

canceled out when the signal is summed to mono.

Checking for phase issues in stereo tracks

You can use the Phase Analysis window to check

the overall polarity of a stereo mix. Figure 10-31 is

an example of a full stereo mix that has phase

issues, as indicated by the majority of the signal’s

energy, which is predominantly skewed to the left

side of the rectangular view (left) and spread along

the -y axis in the polar view (right).

Figure 10-31: A stereo mix with phase issues.

Figure 10-30: Two identical audio streams in the Phase Analysis.

Perfectly in phase One-sample delay Twenty-sample delay

Polar view

Rectangular

view

Inverted

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MOTU Audio Express Guide de l'utilisateur Page 71