iZotope RX 2 Advanced Review

Jan 1, 2011 9:00 AM, By Michael Cooper



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Figure 2: The Denoiser plug-in allows independent attenuation of tonal and broadband noise components.

Figure 2: The Denoiser plug-in allows independent attenuation of tonal and broadband noise components.

RX 2 Advanced proved invaluable while re-recording (engineering the final mix for) an independent documentary video. During one outdoor scene, the Denoiser greatly tamed broadband noise from distant traffic that all but buried very quiet dialog. I could achieve more than 4 dB of noise reduction without producing any watery artifacts or dulling high frequencies. In another scene, the Declipper completely rebuilt squared-off waveforms and purged distortion on a dialog track that had been recorded too hot and had clipped hard. Amazing.

The Hum Remover includes a mode that supposedly lets you hear only the hum component of an audio file for easier adjustment of control settings, but I heard total silence instead. While moving some of the plug-in’s controls, audio is momentarily passed through unprocessed, which is a distraction when fine-tuning settings. Despite these annoyances, the Hum Remover was phenomenally effective in removing 60Hz hum and its first and second harmonics from a dialog track recorded with a poorly grounded lavalier mic. I could completely remove the hum without significantly changing the track’s timbre. And on a Foley track, Free mode let me manually dial in the corrective frequency and Q settings to eliminate a 153Hz hum of unknown origin.

On a voice-over track, Declicker seamlessly removed lip smacks while only very slightly reducing depth. And the Denoiser transparently reduced broadband noise around 9 dB on a noisy music track (see Fig. 2).

Spectral Repair can remove sounds that no other processor can touch. It uses interpolation of surrounding material to seamlessly fill in the resulting holes. I felt most comfortable using the plug-in version of Spectral Repair. As the audio files for the video didn’t include timecode metadata, exporting to the stand-alone version would have made subsequent lock-to-picture of the repaired files prone to error after importing them back into DP. That said, the interfaces for the stand-alone and plug-in versions need improvement.

The plug-in version offers real-time previewing (allowing you to hear the results of your control settings before rendering), while the stand-alone version currently doesn’t and requires a workaround. With the stand-alone version, you can undo, change your settings and process your selections again to hear the result of different settings. Alternatively, you can use the included Compare function to cache the effect of different settings for comparison purposes before committing permanently; after the caching is completed, you initiate playback to hear the cached results in turn. Neither the Undo nor Compare workarounds allow pre- and post-roll playback around the events you wish to process (the plug-in allows this), forcing you to evaluate the processing of split-second-duration events in isolation from the surrounding material you wish to preserve.

Despite its shortcomings, the stand-alone version of Spectral Repair offers a few advantages over the plug-in. Its spectrogram has a scrolling playback wiper that makes it much easier to identify the exact location of noises you want to eliminate. (iZotope hopes to include this feature in the plug-in in a future release.) The stand-alone version can also automatically find similar events to the one you’ve currently selected; this makes it much easier to, for example, remove several chair squeaks in turn without having to separately search for and manually select each one for processing.

I got my best results using the Lasso tool to select multiple objects—by drawing a border around them with my mouse while holding the Shift key—to process in the spectrogram. To my amazement, I was able to completely remove three very closely spaced and loud broadband clicks embedded in a music production’s final mix without inflicting any audible penalty whatsoever on the desired material. (The frequency bandwidth of the clicks was too wide for the Declicker to be effective.) Like removing sugar from a cake after it had already been mixed and baked, Spectral Repair did the impossible.

Most of the modules for RX 2 Advanced work brilliantly. The Hum Remover is a little buggy but nevertheless yields terrific results. The user interface for Spectral Repair needs improvement but won’t stop you from attenuating or removing seemingly intractable noises. The learning curve is a little steep due to a somewhat poorly written and insufficient operating manual.

Few products astonish this seen-it-all engineer. RX 2 Advanced—especially Spectral Repair—floored me. RX 2 Advanced offers a world-class toolset that’s indispensable for anyone involved in audio restoration and archiving, forensics, post-production, music mastering and cleaning up noise-riddled tracks recorded in poorly isolated home studios.

Mix contributing editor Michael Cooper is the owner of Michael Cooper Recording in Sisters, Ore.

Click on the Product Summary box above to view the RX 2 Advanced product page.

Click on the Product Summary box above to view the RX 2 Advanced product page.

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