CAM9: Phase Corrector

Eliminating timing errors and the resulting audio degradations

CAM9: Phase Corrector

The Problem

Timing errors can occur whenever multiple signal paths are inconsistent with each other. The resulting distortion of the phase relationships between the signals and the consequent filtering effect cause many problems including loss of high frequencies, muddy bass, poor mono compatibility, and a general smearing of the image. Worse still, if the timing error is not constant, you can hear a flanging effect.

Audio engineers have traditionally employed a range of processors to hide these deficiencies: equalisers, stereo enhancers, dynamics processors and reverb units. However, none of these attack the heart of the problem - the small but significant timing errors between the channels.

The Solution

The Phase Corrector corrects these problems not by masking them, but by eliminating them. It does this by identifying any monophonic component(s) common to a reference channel and the channel(s) being corrected, and then measuring the timing differences between them. If any such errors are detected, the system recreates the signals so that they are accurately aligned. It will track any changes in the error, dynamically updating the amount of correction it applies at any given moment. A manual mode allows you to shift a signal by as little as 0.01 samples - an offset of just 0.1 microseconds at 96kHz.

A sophisticated filter minimises the chance that the detector will be fooled by unusual signals that contain little or no monophonic components, so that CEDAR Cambridge should never generate false corrections and introduce phase/time errors of its own.

The Phase Corrector allows you to select which tracks are shifted automatically, which are shifted manually, and which (if any) are left unaffected. You can select any channel to be the Master Channel, and the module will calculate the independent timing errors of all the others, thus allowing you to lock-up the imaging for multitrack, 5.1 and 7.1 material.

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