Here’s a neat trick that’s subtle enough to turn the heads of attentive listeners without distracting from the musical impact of a featured track. Start by recording the part onto one track. Then double that part by recording it onto a second track as an overdub—but take care not to play it exactly like the original. Take a few liberties with the timing, the articulation (slide into a note instead of striking it, etc.), and maybe even the choice of a note or two (but do this last one sparingly, as it can come back to haunt you if you overdo it). Now here’s the “trick:” You’re going to send this second part through a delay or reverb while leaving its dry signal out of the mix entirely. The original track will provide the “dry” signal; the doubled track will provide the ambience.
There are a few ways to do this, but the most flexible is to use the little-understood pre-fader setting—a common option for aux/effects send controls. First, assign the send to the appropriate effects bus (i.e., the one with your reverb/delay patched or loaded in). Typically, this effect will be set to 100% wet; the send control will govern the amount ambience in the mix. Now set the doubled track’s aux control to pre-fader and start feeding signal to the effect.
When set to “pre-fader” the signal going to the auxiliary or effects bus is not influenced by the channel’s fader. Moving the fader up increases the dry-to-wet ratio and moving the fader down decreases it. If you move the fader all the way down (or mute the channel), you’re left with just the doubled guitar’s ghostly effect sound. This is precisely what we want here. Combined with the original track, it sounds like “wrong-note reverb” where the effect is “misbehaving” and deviating from the original signal. This technique is great for atmospheric effects.
If you’re using a DAW, try moving the doubled track earlier in time, so the reverb hits before the dry note.