I love the terminology we use in technology. Augmented Reality; Defragment; GigaFlops; Pre-Delay. If you’ve been around audio mixing—and particularly effects units—for any length of time, you may have seen the pre-delay control and wondered exactly how you can pre-delay something? After all, “pre-“ means before, and “delay” implies after. So it’s like saying, “before-after.” What’s that all about?
Perhaps the best way to think of pre-delay is “the time before the delay.” That is to say, how much time elapses before the delay (or effects) start. You typically see pre-delay on reverb units. The pre-delay control essentially allows you to create a gap between the time the reverb unit is first excited and when it starts spitting out it’s warm, rich, diffuse sound.
When To Use It
Almost all signals can benefit from some amount of pre-delay. How much will depend on multiple factors. But first, why do we want a gap between the original signal and the reverb? Mainly it’s about articulation. If the reverb starts before or just as someone finishes singing a word, it can be hard to hear that word or phrase. Reverb by it’s very nature is diffuse and lacks clarity. When you add a lack of clarity (that’s a mouthful, huh?) to the end of something that should be clear, it makes it hard to understand.
If you only have one reverb unit in your system and everything goes through it—that is, everything that you are putting reverb on, don’t put reverb on everything—then you will have to come up with the best compromise. Usually, the vocal will dictate how much pre-delay in that case. I find I like to have about 30 msec. of pre-delay on my vocal reverbs. That’s not a hard and fast rule, but it seems to work well most times. For drums, it might go a little less. Acoustic guitars might need more. Or less, depending on how it’s played and the tempo of the song.
If you have multiple reverbs—as you are likely to on a digital console—you can customize the pre-delays for each effect unit and each purpose. But don’t get too caught up in this. If you have a mid-week rehearsal you can record and then play around with in virtual soundcheck for a while, you can dial in the pre-delay just perfect. But, if you’re in the situation I find myself in, which is to say we rehearse for an hour or so then have a service, just set a round 10-30 msec. of pre-delay and don’t worry too much about it. As you have time, you can grab some tracks and find a setting that works well for vocals, guitars, drums, whatever. Use that as your starting point and tweak if you have time.
Pre-delay isn’t going to make or break your mix. However, if you add some pre-delay to your reverbs, you’ll find you can use longerand more reverb and still have plenty of clarity. And if you’re like me, that’s a good thing.