When two or more sources are used to record a single instrument, there is an inherit delay between the tracks, because each mic will be a slightly different distance from the instrument. Examples of this would be a snare top and snare bottom mic; miking a guitar while also taking a DI split; or having a close mic and a room mic on any instrument. When these audio tracks are summed without compensating for this offset, some frequencies will cancel each other out, while other frequencies will build up – an effect known as comb filtering. To eliminate this problem Sound Radix has designed an easy to use time-aligning plugin that will automatically compensate for delay between any two audio tracks. Auto-Align can help not only with phase issues, but by aligning your tracks it can add some attack and punchiness to the sound as well.
To use, you insert Auto-Align on the track you intend to time-shift, and set the side-chain input as the track you want to align it to. Then simply hit play in your DAW, then engage the ‘Detect’ button on the plugin, and you’re pretty much done. Auto-Align will take a few seconds of playback to run its detection cycle and determine the delay between the tracks, then it will continue playing with the delay automatically compensated for. You can also set it to check if the tracks are polarity-reversed and correct for that as well, or do it yourself using the polarity switch. If you are using the plugin on drums or any other source with a lot of additional noise or bleed, it has noise floor faders that easily remove unwanted content from the detection algorithm.
I tried the plugin in several situations (between bass mic and DI, snare top and overheads, etc.), and each time it worked flawlessly. Any phase weirdness was eliminated and transients cut through the mix easier. However, when I aligned the same tracks manually and compared the results, they were the same as when I used Auto-Align. With a price tag of $149, most users will want to stick to manually time-adjusting tracks, but the plugin does include some interesting features that keep it from being a bare-bones time-aligner. It includes a visual display, input and side chain level displays that show frequency content, the ability to choose different phase matching points, and a counter that tells you how much delay was detected. It can be tempting to have a fool-proof and sample-accurate method that only takes a few clicks of the mouse, but those savvy enough to do it manually will likely continue to do so. So far, Auto-Align is only available as an Audio Unit plugin, but RTAS and VST versions are in the works. –Mike Bauer
