When using digital reverb there are 2 main types you'll come across, Algorithmic and Convolution. Algorithmic is incredibly versatile and can emulate multiple classic types of reverb by using delay taps and filtering; convolution allows you to use any impulse response to define the characteristics of a space.
Most of the delays you use will be algorithmic - even if they say spring reverb or plate reverb they are being created using an algorithm. This is done by using multiple delay taps at various levels and with EQ filters to simulate the reflections of a room or reverb device.
That said, let’s listen to algorithmic emulations of plate, chamber or room, and other algorithmic emulations to better understand how versatile this form of reverb is.
Convolution or Impulse Response reverb is created by using an impulse response, which is a transient recorded in a physical space. This impulse or recording gives the plugin information about the size of the room, the frequency response or nodes and antinodes, the attack and decay times, and more.
This is a very versatile form of reverb since you can find and load various impulse responses to create realistic reverb.
Convolution reverb gives us an easy way to create our own reverbs - all we need to do is record a clap or other sharp transient in a room that we want to emulate. We’ll edit it to get just the transient and the tail, then export it as a WAV.
We’ll then load it into a convolution reverb and now we have that room available as a reverb setting. So if you’re ever in a great-sounding room and you have a portable recorder, you can record an impulse and use it in your music.
Timing reverb is incredibly important since your reverb’s RT60 and decay will either enhance or detract from the musicality of your mix. To time reverb, or other time-based effects, take 60000 and divide it by your session’s BPM - this gives you a quarter note in milliseconds.
I can now use this value, a multiple, or division of it to create in-time reverb. So if I wanted a whole note, I’d simply multiply it by 4.
Equalizing your reverb can help your reverb blend in or stand out depending on what you’re trying to accomplish - for example, I’ll create a send and insert my reverb on the aux track, then I’ll insert an EQ. With this EQ I’ll boost the highs and dip the lows.
This will create a bright, more noticeable sound. Some plugins like the FabFilter Pro-R include a reverb in the plugin itself.
Making an instrument blend in with reverb can be a challenge, but the secret is isolating the reverb to the mid frequencies. This keeps the reverb from sounding bright or boomy, and adds the reverb to an already dense area in the mix, making it blend in seamlessly.
For an even better blending effect, time this reverb like we covered earlier.
Let’s look at some common reverb functions and explain what they mean; the room you emulate will alter your reflections, Time is how long it takes the reverberated signal to decrease by 60dB, whereas your decay rate alters the tail in of your reverb, but can affect the RT60.
Size alters the attack and release of the reverb, as well as the density of your reflections. Diffusion determines if the original signal or the early reflections create the reverb tail. Lastly, pre-delay is the amount of time in milliseconds before the reverb affects your signal.
Other reverbs sometimes combine some of these functions or omit them. Let’s listen to the ones listed here.
Sometimes reverb can cause the signal to get lost or become more difficult to hear - to avoid this, use a pre-delay time of 10 to 50ms to let the transient pass through unaffected. Additionally, attenuate the reverberated signal from around 1.5 to 3.5kHz, to keep this area dryer.
Combined, these 2 steps will help retain the clarity of your signal. Let’s take a listen to a vocal with these settings used.
Automating reverb is a great way to add some complexity to your mix - if we go into our automation settings we can adjust just about any parameter of the plugin. So say in a verse we want the vocal to be more intelligible we can increase the pre-delay.
Or for a creative effect, we could increase the RT60 to its max value then quickly drop it back down. This really opens up a lot of possibilities.