Create a convincing double-tracking effect in Logic Pro X.
Double-tracking is a great way to thicken up a vocal or instrumental recording, but it's not always practical to record multiple performances. In days gone by, engineers would set up ADT, or Auto-Double-Tracking, by recording a vocal part onto tape and using the delay between the record and replay tape heads to achieve a double-tracked sound. There are numerous commercially available plug‑ins that offer the same sort of sound, but did you know that Logic already has everything you need?
There are numerous commercially available plug‑ins that offer the same sort of sound, but did you know that Logic already has everything you need?
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Logic's Pitch Shifter is a good choice for fake double–tracking, but since ADT is most often used on vocals, and most vocal recordings are mono, there are a few steps to go through before you load it up. Pitch Shifter is a stereo plug‑in, and to instantiate it in stereo or dual–mono mode on a mono vocal track requires that it comes after a mono-in, stereo-out plug‑in. If you don't set it up in this way, you'll find your vocal suddenly moves off to one side of the stereo image as soon as you've inserted the Pitch Shifter plug‑in. Logic's Direction Mixer offers a good solution for this (Screen 1), as it allows you to collapse the stereo width to mono prior to any further processing, while still letting you use stereo and dual-mono plug‑ins.
Once you've set that up, insert a dual-mono instance of Pitch Shifter, which you'll find in the Pitch section of your plug‑in list (Screen 2). Set one side to a +3 or +4 cents shift and the other side to a similar minus amount, and you have the classic detuning patch, as found on classic Eventide effects units, and very popular with '80s guitarists.
If you also set one side's Timing type as Vocals and the other to Manual, you'll be able to increase the delay time on the Manual side to add a little delay between the left and right channel (Screen 3). Something around 25ms works well. You can either set the Mix parameters to 100 percent wet, which will yield the classic double-tracked, hard-panned sound, or you can allow some of the unprocessed sound to get through, which in effect gives you three voices: double-tracked versions left and right, with the original recording in the middle.
This treatment works well for thickening vocals or beefing up big guitar solos, and if you find it useful, you can save it as a Channel Strip Setting or put it in your user library for next time you need to call upon it.