Reverb: Tips and Techniques
I figured since a lot of questions have been asked, it was time to just post up with some tips for the peoples. Everyone has a different take on how to create space and environment. This is just my approach.
What is the major advantage to miking an instrument vs. going line in? Guaranteed, it is the sense of real space. Space is as much a part of the music as the music itself. It's the illusion on record that not just presents the sound, but takes you to another place, allows you to "zone out." Literally, this means to leave the zone, or space, you are in, and go somewhere else.
Spatial processing is a rough science. There is a mathematical component, and an artistic component. The advantage to artificial reverb is that you can negotiate the math to bring out the art, by create surreal environments.
But too often, we underplay the value of good reverb or we get lazy in our approach. Or, we overplay the value of reverb, and turn our reflection up way too high. Lastly, we forget about the musical context of reverb, and focus too much on reality - disregarding that reverb is still a sound element in our mix with rhythm and tone.
Let's start with the overplay of reverb as this is an easy topic. Less is more. In a live setting we tend to hear a lot of room sound - but realism is probably not our primary goal. It can be - but often times we want the music to be crisp and defined. Lots of reverb is the enemy of crisp and defined. But a little reverb can add depth and energy.
Artificial reverb uses a series of mathematical algorithms to generate new sound based on the source material. This includes any reverb that is already in the source material. Artificial reverb sounds better when you have a bit of real reverb feeding it. Why? Because it ends up bringing out that real space sound. This doesn't mean record in a church, and then add subtle artificial reverb (you can of course). Rather, it means, don't expect a totally dead room mixed with an artificial reverb to sound good. This is a common problem I call "studio dark;" that endless dark abyss that shows up on too many studio recordings. We all know that an amateur mistake is to over pad a vocal booth with acoustic foam - you get a tight, dead room, and a muffled, dead sound. We're much better off with a decently sized room with appropriately placed absorbers and diffusers. We can use artificial reverb to exentuate and control the tone and rhythm of our natural reverb! - Oh, side note - if you have a synth going line in, you may want to consider miking your monitor to get the actual capture you're going to use, just so you can have that real space in there.
Now, you need to have a good idea of how each instrument will function in the song. The prominence of the instrument will determine how live the reverb should sound. Why? The reverb is going to reinforce whatever is feeding it. If you have a lead vocal generating a flat reverb, and the drums generating a bouncing reverb, your drums are going to get the attention - which can be good or bad, depending on the scenario. That being said, let's say you want the lead vocals to be the focus. Instead of throwing a compressor on your lead vocals, bus your lead vox to an aux channel, and then compress. Go to the uncompressed vocal channel, and throw an aux send to your reverb channel. This will give you controlled vocals, but live space!
We will be sending other instruments to our reverb channel, but let's focus on getting the reverb right on just our lead. If we can get it right here, everything else falls into place. To do this, we need the reverb loud, the diffusion and decay/density and room size all the way down, the time, and the predelay all the way down. You may have to turn the time up a little so you can actually hear the reverb, but you want to hear it as close to a pulse as possible.
Start with the predelay. This is the first rhythmic element of your reverb. Let's say your bpm is 120. That means you have one quarter note every 500ms. You have one eighth note every 250 ms. You have one sixteenth note every 125ms, you have one 32nd note every 63ms. 64th notes at 32ms. In order to have the predelay trigger the reverb in a rhythmic fashion, it needs to be at one of these measures. I'd go with 32 or 63ms, because we want the reverb to still feel attached to it's source sound. Also, you notice how I rounded up? That's to put the reverb "behind the beat." This helps create a rhythmic pocket. I might even suggest moving the predelay higher a couple ms, just to make that pocket a bit more open, and so that the hit of the reverb isn't directly overtop the next part of the music.
Now move on to the Duration. Using the same time rubric, we can determine how long we want our time to be. Texturally, we want our reverb to be clean. This means a long time is going to create a wash sound, and defeat the work that we did on the pre-delay. The reverb time in a small room is very quick. A quarter of a second, give or take. But rhythmically, we want our reverb to pull us into the meter of the song. So we want our length to line up along the same rubric we found for the predelay. Let's say 250ms if we're going for a room slap effect. This way, we're moving right along to the eighth note pulses. BUT! Consider that our predelay is set to, say, 34ms. This means we have the tail of the reverb pulling us to the beginning of the next reverb, not the beginning of the next pulse. Subtract your predelay from your time, 250-34ms. Set your reverb time to 216ms. Remember, even if you don't hear the difference between 216 and 230, if the track is going to get heavily compressed, that difference WILL stand out. Now, for a lot of applications you might want a longer tail reverb - less of a room slap and more of a bigger resonance. A good meter to use for this 1 bar measurement - which at 4 beats per measure, 500ms per beat = 2 second reverb tail.
EDIT: From three years in the future here. Choosing a duration for rhythmic purposes is about deciding where you want the reverb to pull the ear into. If you are doing a dance song, with a snare on 2 and 4, a short slappy reverb sound on the snare that rhythmically connects the 2 beat to the 4 beat might be good. From the example above that a 1 second duration. But let's say you have a vocal - you may want the phrases to connect which would require a longer reverb - this has a lot to do with feel because phrasing can vary a great deal - but a 1 measure reverb may in fact be better.
-Side note- predelay and time are subject to taste. Use the math to get where you want. I usually find the math gets me right there. But make adjustments and go with what sounds best.
Size. Size will effect the tightness of the sound. This is more creative, but here's a good starting place: Divide your time by ten, and round to the closest integer. That's a good number of ft for your room size. Adjust up or down according to tone and texture. Too large will get a spacey characterless sound. Too tight will sound almost more like a echo/delay.
Decay/Density. This is somewhat ambiguous, and different processors will give you different results. Basically, I equate this to presence. Remember you have your reverb up loud now, so adjust the presence to match with the instrument that's feeding it. You probably want your reverb a nudge less present than that. Consider it like a "tone" control. If you hear a metallic oil tank sound you may want to turn the density up, but if you hear the reverb washing out or masking other sounds in the mix, you may want to turn it down.
Diffusion. Diffusion is the scattering of sound waves. A highly diffuse room tends to make things sound very distant, open, or haunting, whereas a non-diffuse room makes the reflections sound more like one unified echo that washes back at you. I find diffusion can help add a sense of being "further away" without actually changing time constants.
Damping. Picture the material you want your room to have. Is it metal walls? Is it oak wood? Picture your ideal room and how it sounds, then adjust the damping to meet that. Damping is how long frequencies persist during the period the reverb is presence. Basically fiddle until you get it right. Your going to eq in a moment anyway.
BUT FIRST
Compression? Sometimes, there is a lot of attack sound in reverb. Especially when hot transients from your drums are feeding into it. It might be worth taking a compressor and setting as fast an attack as possible and a really quick release, just to ease off the transients. But be careful. Compression will eat the energy out of your reverb (if there's too much energy afterall, that's the point). Err on the side of caution, and if you're not sure, leave it out. I find I don't usually need to compress out the transients in the reverb. But every now and then, I do.
Ok, now EQ. The idea of the reverb is to lie underneath your sounds. You will find that as other instruments start feeding the reverb, you get fatty build up somewhere in the high mids, somewhere in the mids, and sometimes in the bass/sub bass. Your goal is to find the fattest point in these three sections and use a wide bandwidth to ease this build up away. A HP filter may not be bad to get rid of the bass build up. You can generally cut out anything below 70Hz. Be honest though, that rule doesn't apply 100% of the time - maybe 90% of the time.
FINALLY, start lowering the sends on each instrument individually. Solo one instrument at a time. Lower the send volume until the reverb exists, but the total clarity of the instrument is still present. After this is done for all instruments, start adjusting the send levels by little bits based on what sounds best: Here's a tip: Normally we like to put heavy reverb on things like strings and pads. While that seems logical, it's actually not the way to go. Think about this, if you have a constant tone playing at one level, even if it's way down in the mix, won't it stand out? Take instruments that naturally sustain at one level, or have lots of compression on them, and reduce the amount of reverb. The more dynamic instruments like vocals, should have the most reverb. That means drop the reverb in your heavily compressed drums, and your sustaining pads - not boost the reverb on your vocals. Less is more.
NOW, the final test.
Mute your audio. Mute your reverb aux channel. Wait a minute, shake your head out. Stand up, get a drink of water. Come back and unmute your audio.This is the dry sound, no reverb. Listen for a moment, then unmute the reverb. Does it sound like the song just came to life!?
If it does - your done. If it doesn't, it's back to the drawing board.
Last edited by Storyville; 14th October 2009 at 05:20 PM..
Reason: I can't do math