Mastering reverb by getting creative when mixing with reverb
By Rob Stewart - JustMastering.com
Adding reverb to different elements of your mix can have an immediate, obvious impact. There are many ways you can mix reverb that can have a dramatic impact on its effect. Here is a list of my top reverb mixing tips and techniques that you can use with any reverb processor you have.
Choosing the Best Reverb for your mix
Picking a reverb program takes vision, practice and a good imagination. Choosing reverb can be a daunting task because reverb processors come with hundreds if not thousands of tweakable options, offering you infinite possibilities.
I like to first think about what type of space I want to place the elements in. For example, do I want a realistic space such as an impulse response convolution program of a real concert hall? Or maybe I am not going for realism, and want something completely unique, from my own imagination?
Next, I narrow my choices down based on the overall character I am going for. For example, if I am going for realism, I need to think about the type of venue (Church, Concert Hall, Bar, Lounge, Studio etc.), and the size of the venue. I decide that based upon what mood or emotion I am trying to support in the mix.
Setting Reverb Levels in your mix
There is a point at which a reverb will start to overtake the mix, where when it is pushed too far, things will lose their focus. Sometimes you will want that for certain elements. Varying the amount of reverb from one element to another helps improve the depth of your mix by creating the illusion that certain elements are further away (i.e. the listener will therefore hear more of the space that the element is in, and less of the element itself) than others. On balance though, if your mix is "too wet" it will lack impact. Contrast is important.
Reverb levels can accumulate as you mix, and it can be easy to overlook that because it has a sweetening effect that can be addictive. The best thing to do is monitor, evaluate, monitor and re-evaluate often. Some time away from your mix will help as well, so that your ears can reset themselves. If you are in doubt, consider setting the reverb on each mix element where you think it feels good, and then dial it back a bit. Revisit the mix the next day, and you will hear right away if certain elements need more or less reverb, making it a little easier to know what to tweak.
Setting the Reverb Pre-Delay
Pre-delay is easily overlooked on many processors because it is often preset for you. It is a small delay that is placed before the reverb effect starts to slightly separate the mix element from the reverb. A pre-delay value of 10ms means that the reverb will start 10ms after whatever you run through the reverb. If your reverb program does not have a pre-delay setting and you feel you need one, you can insert a delay plugin before the reverb to create a short duration delay.
Pre-delay helps contribute to the sense of size/depth of your mix by creating the illusion of positioning mix elements in space, relative to the listener. A longer pre-delay will create the illusion that the mix element is closer to you than the rest of the space, creating the illusion that it is closer to the front of your mix, relative to other mix elements. A shorter pre-delay will further "immerse" the mix element into the reverb, helping to push it further back into your mix.
If I am mixing music, I will often set pre-delay times based upon the tempo of the song so that it is "in time" with the beat. For example, if the song is 120 beats per minute (BPM), a 32nd note is just over 31ms, and a 64th note is 15.6ms. Therefore, 8, 15 or 30ms pre-delay times might be good starting points for that tempo, depending upon the song the mix elements and how close/far I want the mix element to be.
Pre-delays can be more or less obvious depending upon how percussive the mix element is. For example, you will easily notice a 20ms pre-delay on a snare, but less so on something with a very slow attack time. Setting the pre-delay is very much based on feel, and with constant monitoring of what you are hearing the pre-delay do to the character of the mix element in your mix. The key to remember is that the shorter the pre-delay, the further away your mix element will typically sound, relative to other elements.
Using or adjusting the Reverb's Early Reflections
Our brains assess early reflections to determine how large a space is. A large amount of very short and dense early reflections will create the sense of a small room. Imagine standing in a small empty room in your home, talking or clapping your hands and hearing the character of that room. Many people notice this effect if they move their furniture out of their room because there is no longer anything in the room to soak up all those reflections.
Now, imagine standing in a large, vast space where the walls of the space are 50 or maybe 100 feet away. Clap your hands or speak, and the early reflections will be much different because they will only be coming from the floor, or maybe the ceiling for the most part. This is how - even with our eyes closed - our brains can assemble a very powerful impression of the size of a room based in part on the early reflections.
Sometimes, I will reduce or even remove early reflections if I want to create a really clear reverb with emphasis on the more obvious later reflections. Other times, if I am going for a very intimate sound, I will emphasize early reflections to create a slightly boxier more up close, small-space sound. Early reflections are well worth experimenting with, and once again it is very much based upon your vision for your mix, and your imagination.
Setting Reverb Tail (Decay Time) in your Mix
When mixing music, setting your reverb times according to the song's tempo will help minimize congestion, mush or mud in your mix. Decay times will really depend upon how dense your mix is, the tempo of the song, and what character you are going for. For example, if I am using a longer reverb program on a slower song, I will set the decay to a half measure (1000ms for 120BPM) for a medium reverb, or 1 to 2 measures (or longer) for a long reverb. There is no hard fast rule, though. The shape of the decay (more about that, below) will also influence how long a decay you need.
Using Equalization (EQ) with Reverb
Note that this tip applies only if your reverb is on an effects return bus, with the wet/dry control set to 100% wet.
I almost always EQ my reverb returns. Depending on the situation, a heavily low-passed reverb can be useful. For example, it can sound great on acoustic guitar where you get the brightness of the guitar, enveloped by a really dark sounding reverb that contrasts really nicely with the direct sound. That effect will usually create a rich sound with both depth and height. Other times, the opposite is useful where I will EQ a reverb to sound more bright on some types of percussion to reinforce the brightness of the direct sound.
I will often EQ my reverb sends. Some reverb processors can sound a little metallic or strident if the mid or high frequency transients are too strong. Again, a lowpass filter or bandpass filter can be a big help in only sending the tonal elements to the reverb that you want processed. A snare drum is a good example where depending upon how the snare was played and recorded, there will be a lot of sound above 500Hz, but there will also be a lot of sound below 500Hz, with a lot of energy down to 100Hz or lower. For some situations it can be helpful to only apply the reverb to the darker portions of the snare's tone. Applying a low-pass filter before the reverb program on the snare can therefore do a great deal to shape the snare's sound.
You will find that if you use a low-passed reverb that you can often "push" the reverb a little higher on some mixes, as long as the rest of the low end of the mix is wide open enough to absorb it. A dark reverb can really help define a "backdrop" for certain mix elements that way.
Using Multiple Reverb Programs in your Mix
Depending upon the mix and the situation, it can be a great idea to use more than one type of reverb. This works well when you are going for a traditional pop/studio style sound. If I am mixing a live performance, I tend to choose only one reverb program, or maybe 2 variations of the same program, for example two of the same Concert Halls, one with and without pre-delay.
With popular music, sometimes you will want to use different types of reverb in your mix, perhaps a plate style reverb on your vocal, and a spring reverb on electric guitar. There are no hard fast rules. In my view, it is a good idea to have some variety but if you have too much variety then the listener will not pick out the subtleties of what you have created. Having two or maybe three different reverb programs is a good starting point.
I generally do not use more than two or three reverb programs when I mix, but, I will often have two reverb buses that have the same basic preset (e.g. a concert hall), one with and one without pre-delay (sometimes 3, to accommodate two levels of pre-delay). Sometimes I will expand on that and add a few more buses with the programs EQ'd slightly differently (one EQ'd for drums, one for vocals or guitars). This way, I can maintain some sense that everything is in the same space, while using EQ and delay depending on where I want to position certain elements, and how much tonal contrast I want between the direct and processed sound.
Using other Effects and Mix Automation with Reverb
Note that this tip applies only if your reverb is on an effects return bus, with the wet/dry setting to 100% wet.
Sometimes I will add a stereo chorus after a reverb, or even a slight delay between left and right channels (10 to 20ms). Either of these effects can be effective on pad sounds or vocal reverbs depending upon the song, because it can help create a more ethereal quality. Don't be afraid to experiment.
Distortion either before or after a reverb can be highly effective on percussion, where it can really help add impact to the sound, and make the reverb sound more "immediate".
I will sometimes add a gate, or an expander before the reverb's input. That can make a real difference in some situations if I am finding that the reverb is not following the dynamics the way I would like. It can be especially useful on percussion or other highly dynamic elements where you may want little to no reverb on quiet passages and then a lot more on the loud hits. Gating can really help if you are layering short and long reverbs on the same element and want to control how and when they are activated (e.g. a short reverb that is on all the time, and then a longer reverb that kicks in on the loudest passages).
I use mix automation to adjust the volume or even mute the reverb send or return depending on when I need to hear it. That approach can be great on pads and pianos where you might want the ambience to "ebb and flow" with the dynamics of the performance. Applying automation to the return allows you to sculpt the decay at key points of the song where you want the decay to fade away more quickly or more slowly than the rest of the song.
Other settings such as Shape, Width, Density, Diffusion etc.
All of these settings depend heavily on the mix because width for example will come into play if you need something to sound more distant, or more focused (e.g. a completely mono reverb on a snare drum). Density and diffusion relate more to the overall character of the reverb program, often changing the relationship between early reflections and decay. Density settings typically adjust the amount of reflections (more reflections = more density). This can be helpful if you need to either "thin out" or thicken a reverb for your purposes. Shape is typically the shape of the decay. For example, is it a straight slope from start to finish, or does it ramp down quickly or slowly (nonlinear slope).