Pre delay is arguably the most nebulous settings on a reverb plugin. Let’s demystify pre delay by explaining what it is in the context of reverb, and how much pre delay you should use.
What is Pre Delay
Pre delay on a reverb dictates how much time is inserted between the dry audio and when that reverb plays. For instance, set the pre delay to 500 milliseconds on your reverb on a snare drum and it will be a full half a second after the snare hits before you hear the wet, reverb soaked reflection of that snare.
Why Use Pre Delay
Pre delay is useful because it creates separation between the dry, unprocessed audio, and the wet reverb instance of it.
This separation is important for a couple of reasons. One, it helps to maintain the transients of your tracks which helps to maintain a punchy mix.
The transients are the high frequencies which precede lower frequencies in hitting your ears first, drawing your attention to a track in the mix.
The instrument I frequently like to reference is the snare as the crack of the stick on skin precedes the fullness of the rest of the snare when it gets hit. That sound is its transient and helps the snare cut through the mix (see what are transients for more information).
With no pre delay, the thickness of the reverb will swallow up or dull the punch of most of the tracks in your mix. Note that other factors come into play with this, as well, like how much wetness you’re using on the reverb, if you’re using it as an insert vs a send, etc., but pre delay is always useful for creating that slight separation.
Pre delay also helps to characterize the size of the room or reflection which you’re simulating as well as the depth of reflections of sound off of surfaces (as I discussed in my comparison of low frequencies and high frequencies).
A shorter pre delay generally represents a smaller room as those walls are closer, causing the reflections sooner.
Conversely a longer pre delay represents a larger room as it takes longer to hear that reverb “reflect” back.
How Much Pre Delay to Use
Now what we understand what is pre delay and why it’s important alongside the rest of your reverb settings, how much pre delay should you use? Where should you set it on your reverb?
While the Haas Effect states that when two sounds are generally anything less than 40ms apart, the ear perceives them as one, this doesn’t apply exactly the same with setting pre delay on our reverb.
The key is to use at least a few milliseconds of pre delay in order to create that separation between the dry and wet instances of the audio so that the transients can come through.
You can liken this to adding a small bit of attack to your track’s compressor. You don’t want that compression to engage instantly as this will pull down that transient so the track will lose its punch in the mix.
Also factor in that, as I just mentioned, if you’re simulating a larger room then that calls for more pre delay than if you were simulating a smaller room.
If you’re not sure how much pre delay to use then be mathematical about it.
Use this calculator to simply enter the tempo of your mix and see what amount of pre delay you should use for whichever interval you want.
Just enter in the BPM of your song and it will tell you not only how much pre delay but how much decay time to create for each interval.
By interval I’m referring to if you want it to last a quarter note, half note, full bar, etc.
Syncing your reverb up with the tempo of your song keeps the reverb tight in general so that the tail of the reverb fully decays before the next interval. This keeps the reverb clean and from stepping on the next drum hit, note, etc.
Don’t overthink pre delay when you’re setting, but be sure to understand its importance and role in your greater reverb and how it sounds. Just remember that it’s essential for keeping your track punchy as well as helping to realistically simulate the room size you want in your mix.
Check out my tutorials on reverb for more tips on pre delay and setting your reverbs on various tracks in your mix in general.