Sonnox Oxford Restore Plug-In Suite Review

Feb 1, 2010 12:00 PM, By Barry Rudolph



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The Restore restoration suite from Sonnox is the result of 18 months of research into developing new tools that exploit recent advances in computer and software technologies. This Native suite comprises DeClicker, DeBuzzer and DeNoiser, which are available in RTAS (for Pro Tools HD, LE and M-Powered systems), Audio Units and VST formats for Mac and PC.

Completely unrelated to the old Sony Restoration Tools and offering no backward compatibility, each plug-in uses a two-step methodology, with a detection section for pinpointing problematic and unwanted noise and a removal section that determines the desired level of repair while minimizing collateral damage to the original audio. Each plug-in offers common functions, including an output section with enable in/out, output level adjust, threshold and sensitivity settings, and a Diff (or Difference) button for monitoring the removal of the targeted noise.

DeBuzzer removes buzzes, hums, whines and whistles.

DeBuzzer removes buzzes, hums, whines and whistles.


DeClicker is divided into three sections, each of which is designed to remove impulse noises predicated on duration. DePop is for noises lasting up to 10ms long, DeClick for 3 ms, and DeCrackle for 0.4 ms. Each section in DeClicker has a mini-display that shows the noise floor and a threshold line with the impulses either above or below it. There is a larger, clever X/Y graphic display that shows each individual noise spike as a color-coded bubble: DePop events are green, DeClick events are blue and DeCrackle noises are white, with unrepaired noises glowing red. In the event that DeClicker removes important harmonic content such as percussive transients or the brightness of a brass section while otherwise repairing well, there is the Exclude Box feature.

Rather than simply bypassing or changing the threshold setting for that particular piece of the audio that would affect the rest of DeClicker's repair, you can use your mouse as a “lasso” around a grouping of bubbles that represent the impulses you want and exclude them from repair. Because the Restore Suite plug-ins' parameters are all automatable, you can move Exclude Boxes and toggle them in and out invisibly.

Unique to DeClicker is the Dialog mode, in which one threshold is set for processing background noise when dialog audio is present and there's another threshold setting for when it is not. The Dialog mode GUI has a histogram of the dialog audio over time with two adjustable horizontal threshold lines. When the dialog audio exceeds the top threshold, it is processed according to the controls labeled Above. When dialog has stopped and falls below threshold, the plug-in switches over to repairing according to the controls labeled Below. If required, the Sidechain mode adds an adjustable bandpass filter to further differentiate the frequencies of dialog audio from background noise.


DeBuzzer detects and accurately measures the fundamental and harmonic frequencies of buzzes, hums, whines and whistles, and passes this information on to the removal section. Using an FFT (Fast Fourier Transform) display that accumulates data over time, a peak profile is created and shown in a small display above a large rotary frequency adjust knob.

In Manual mode, turning this knob will set the fundamental frequency of the buzz over any of the three frequency ranges: LF, MF or HF. Any buzz or hum that is consistently present will stand out on the main FFT display with its three dominant peaks marked with red arrows. Clicking on any of these arrows will reset the fundamental for the removal section to recalculate the coefficients for the comb filter to remove it and its harmonics.

When you insert DeBuzzer into your session, it defaults to Auto mode where the detector continuously “hunts” either side of the fundamental to check for drift in frequency; the removal filters will follow. Freeze mode turns off this hunting process and is the best way to dial in whines or whistle noises in the MF or HF areas.

In addition to the comb filter, DeBuzzer also offers the Para-EQ mode. Generally, the narrow and deep notches of the comb filter do less damage to high frequencies and are the best for harmonically rich buzzes. But if you have only one or two harmonics to remove and the fundamental is above 2 kHz — such as a loud whistle — the Para-EQ might sound better.

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