Last month I looked at the 6 different types of reverbs available to us and a little history on them as well. This month we’ll get into the nitty gritty of actually making these things work.
Since it’s rare when anyone actually uses real chambers, rooms or dedicated hardware reverb units anymore, we’ll just refer to the typical reverb plugins that come with any DAW or from a third party developer.
The vast majority of reverb plugins have at least 2 parameter controls and you can do 98% of what you need to do with them – predelay and reverb decay. The problem comes where they’re set randomly by just tuning by ear, which could lead to a washy muddy mix. There’s a method to doing it and it will make all the difference in how much the reverb enhances your mix.
Reverb Decay
Reverb Decay (sometimes called Reverb Time) is a simple way to refer to a measurement called RT60, which means the time it takes for the reverb to drop 60dB, which is basically the threshold of hearing. Thankfully you won’t hear anything this technical again from me or see it on most reverb plugins. It just gives you an idea of how decay time is measured.
When we say “short decay,” that means a decay time around 1 second or less, while a “long” reverb time is usually over 2 seconds. Long decays tend to push a track back in the mix, and if used inappropriately, will cause the mix to become confused since it’s always awash in reverb. That said, some halls are naturally over 4 seconds and lend themselves to orchestral instruments.
Shorter decay times tend to make the mix element sound larger. In fact, short decays are used all the time on drums, guitars and keyboards. You’ve probably heard the sound but never associated it with reverb.
The best way to set the decay is to time it to the pulse of the song. How, you might ask? Because the reverb tails of virtually every reverb plugin are different (more on this next month), you just can’t set it by the decay numbers. It’s best to set it by ear.
It’s best way to solo up a snare or something that’s steadily creating the song pulse. Dial the decay control so the reverb decay just about dies out before the next hit. Too short? Then set it so it dies out before the second hit.
The whole idea with everything we do in mixing is to intensify the pulse of the song and one of the ways that we do that is to make effects like reverb breathe with the pulse of the track. Setting the decay is just step one in making that happen.
Predelay
The Predelay parameter is vital to a great sounding reverb that breathes with the pulse of the song. What it does is delay the onset of the reverb just a bit, and this separation makes it easier to hear the mix element and keeps it from being masked by the reverb.
Unlike reverb decay, we can set this by the numbers. If we know the general BPM of a track (it doesn’t have to be precise), we’re in business. One way is to look it up on a BPM to Delay time chart that you can find online if you do a search.
Another way to determine the predelay is to insert a delay processor on any track (you won’t actually need to hear it). If the BPM is already programmed into the track (like in electronic music or anything done to a click) you’ll see a delay time automatically propagate. Usually that will give us a ¼ note delay and that’s all we need.
A 120 BPM song gives us a 500 millisecond ¼ note delay, but that’s way too long for predelay. The typical predelay is usually anywhere from around 20ms to about 180ms. Some delays will allow us to dial in lower note denominations but usually stop around a 1/16th note, which in this case is 125ms.
If we want the predelay lower, we just keep dividing by 2 until we get the predelay that we want (62, 31, 16 in this case rounded off). We can also choose triplet or dotted note denominations, but you won’t really hear the difference here. Whichever one you choose, your reverb is now breathing with the pulse of the track.
To be honest, I favor longer predelay times over 100ms because I grew up in the days of using a tape machine to add predelay in front of a plate reverb. There were only a couple of speeds on the machine so you only had two choices and everyone usually chose the longer one, which was in the 150ms or so range.
A long predelay over 100ms works great for vocals and solo instruments, while a short one in the 20-50ms range works best for percussive instruments. When in doubt, set it to at least 20ms.
We’ll go over some of the other lesser used reverb parameters in Part 3, as well as how to make reverb sound so much better with just a few tweaks, and why they can also sound so bad sometimes.
In the meantime, remember that we’re trying to reinforce the pulse of the song, and if we do that, our mix will not only sound better, but feel better as well.
Producer/engineer Bobby Owsinski is one of the best-selling authors in the music industry. His latest, The Music Mixing Workbook, provides exercises to help you learn how to mix on any DAW. Visit Bobby’s website at bobbyowsinski.com.
