Omnia Omnia.9, Installation And Operation Manual

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Input Menu – Undo
What Exactly Is Undo?
In order to understand how to best use Undo, it is helpful to understand exactly what it is and how it
works. Undo is actually two separate processes -­‐ a de-­‐clipper and a multiband expander – which
work together to “undo” the poorly mastered, hyper-­‐compressed and clipped audio found on so
many modern CD’s. (Note: The de-­‐clipper works most effectively when using Omnia.9’s digital
inputs. Regardless of whether your use an analog or digital input, the incoming audio should not be
equalized or pre-­‐processed in any way).
Take a look at the two waveforms below, captured using Omnia.9’s built-­‐in oscilloscope. The top
window shows the unprocessed source audio. The bottom window shows the same audio after it
has passed through the de-­‐clipper. Notice how the peaks that were clipped during mastering have
been restored by the de-­‐clipper. (Note: The oscilloscope gain was kept at the same level for
comparison purposes, but Omnia.9 has sufficient internal headroom, and this illustrations that follow
do not suggest that the audio is being clipped again by any portion of “Undo”).
The second stage of Undo is a multi-­‐band expander that is designed to restore dynamic range to
audio that has been excessively compressed. Each of the five bands of the expander has a
corresponding psychoacoustic dynamics detector and a peak detector that examine the peak levels
of the incoming audio, and based upon that information plus the settings of the various controls,
tells the expander how much dynamic range to restore to the audio.