We humans naturally perform some interesting spatial decoding with each sound we hear. By tracking the microseconds of delay and minor timbral differences between how a sound source is perceived by each ear, our brains autonomously calculate how far away it is and what direction it is coming from. This microprocessor-style analysis is pretty sophisticated stuff. As sounds fade away, their reverberations bounce around and settle into silence, giving our hearing something to digest and mull over as well.
The transformation of initial sonic reflections into the fractal entropy that characterizes reverberation informs us subconsciously about the way energy flows through sound waves. This information is both cosmic and spiritual, a way for our deeper selves — above and beyond our mere intellectual minds — to grasp a larger picture of how the universe works. With all the brainpower needs for this sound processing, it's no wonder that most of the music that's called “psychedelic” relies heavily on spatial effects such as reverb, delay, phase shifting, etc.
But you don't have to believe these cosmic speculations in order to agree that you can create a tremendous amount of sonic intrigue in your mixes by employing spatial effects; there simply would be no dub music without time-based delay effects and sweeping phase shifting, and can you imagine ambient chill-out music without reverb and delays? Not to mention just about every lead vocal track you've ever heard.
36 CHAMBER REVERBS
Reverb as an effect was originally created to make records sound rich, resonant and natural, the same way a live performance sounds in an acoustically pleasing room or concert hall. Reverb as an effect has been the single most crucial type of processing throughout the history of multitrack recording. However, the two biggest ways to screw it up are to use either too much or the wrong kind of reverb. Back in the day, there were dedicated rooms with speakers and microphones that served as “chambers;” a sound would be piped into speakers in the room and picked back up by the microphones in the room as 100-percent natural room reverberation. Needless to say, placement of the speakers and microphones within the chamber would make all the difference.
Another kind of old-school reverb comes from a “plate,” which is a sheet of metal that vibrates when it is hit with a signal; a transducer then sends the reverberations back to be blended with the original signal. That 2-D reverb sounds great on vocals. However, although it is rich and textured, plate reverb does not contain the complexity — or the key early reflections — of a 3-D room.
Traditional use of reverb for a “natural”-sounding mix goes something like this: If you have recorded a bunch of tracks direct or close-miked, you can add varying amounts of a tasteful room reverb to make it sound like everything was played in the same room. That reverb will make a mix sound natural to our ears. Without the reverb, a mix can have an unsettling dryness — in other words, the flat-sounding quality of instruments that have no ambient aura.
For that reason, a very dry instrument or voice will stand out and sound a little weird within the comfortable ambience of a good mix, and that can be used as a cool spatial effect in and of itself: The complete absence of spatial enhancement can be the most radical ambient effect of all in some cases, which is worth remembering while you mix. Without the merciful cushion of reverb however, your track will be exposed beyond nakedness, and any sonic warts will be ruthlessly exposed. The flip side is that too much reverb “clothes” the individual elements of your song into a dense, muddy mix that sounds far away, murky or just grossly amateurish.
Let's say, however, that you have tastefully sent varying amounts of key instruments on an aux send bus to a room reverb effect that you like. You could then take it a step further and change the amount of pre-delay for individual instruments; pre-delay simulates early reflections before the wash of the reverb itself and suggests, among other things, how far away within the room the instrument is.
If you are mixing in the box and have the processing power, you can use multiple iterations of your carefully tweaked reverb plug-in, each with different early reflection/pre-delay settings, which would serve to place the respective elements in different parts of the room itself. Such subtle adjustments add more depth and complexity to a mix that is already in the ballpark, sonically.
Before we go any further with spatial processing, let's remember that the most fundamental way to fit the elements of your mix together spatially is with panning. In general, it is easier to spread out higher frequency elements, which is why kick drums and bass instruments are usually panned up the middle and spread out (if at all) with balanced left-right short delay and/or modulation processing such as chorusing or flanging. Our ears simply can't grasp directional information of low frequencies the same way they can follow the smaller (shorter wavelength) and more manageable higher frequencies. By the same token, using highpass (aka low-cut shelving) filters to get rid of low-frequency boominess in reverberant processing keeps things open and sounding clean.
In our theoretical session, we now have one room reverb algorithm with various pre-delay and/or early reflection settings, and things are starting to sound really professional. But one more subtle thing to add a little spatial complexity would be to look at the panning of the different instances of the reverb plug-ins' returns; panning one hard left and another hard right — either in parallel or opposite the plug-ins' respective sources — is a way to further open up the mix and keep the ears intrigued. But we're still playing it pretty safe here, so let's get busy and freak the mix a little.
So far, we have been looking for realism with our chosen room reverb effect and applying it in subtle and tasteful ways to add depth to the mix while giving it a natural sheen. There are no rules, however, so we can put whatever kind of reverb we want wherever we want and take ourselves out of the realm of cozy familiarity into the spatial abstract.
My advice on whether to use multiple, radically different reverbs in the same mix is simply this: As long as it doesn't sound stupid, go for it. If you are a) using your ears; b) considering the ideas of spatial placement we used earlier with the single-room setting; and probably most importantly, c) really thinking about the physical spaces your reverb algorithms virtually represent, you are in control of the spatial elements of your mixes, as opposed to cluelessly scrolling through random presets and waiting until something sounds okay.
Always remember the old caveat: Too much reverb creates sonic mud, especially if you aren't paying attention to the low-end content going into and coming out of your processor. The rule of thumb is to roll off lows before and/or within the effect; highpass filters at ∼120 Hz are a good start.
Say you experiment for a while and find some great sounds, but when you put it all together, it sounds a little lost. All you need to do is pull back a little on the rich plate reverb you slapped on the kick and snare, reel in the cathedral effect you used to smear your Minimoog melodies all over the background and maybe lower the send a little with all the vocals going to that weird-ass tiled bathroom setting that sounded cute for a minute. Then maybe swap in some delay effects in place of a reverb or two; they'll give you more clarity, less wash and help to preserve more of the open space in a mix.
Back in the '50s, the classic Elvis slapback tape-delay sound was created by sending the vocals through a spare tape deck and mixing in the delayed result — usually about 150 to 200 ms, or the time it took the tape to go the distance between the record and playback heads. Multitap delays, or ping-ponging multiple echoes, take the slapback idea a step further and combine several delays, sometimes feeding slightly back into each other, to create a very coarse-grade (but nevertheless useful) variation on the lushness of reverb. If the multitap delays are in time with the music — typically eighth or 16th notes are a safe place to start — they can become subtle yet effective in simulating an ambient aura around key tracks in a mix.
If you are working in a DAW, you can also make several copies of a track and then offset the copies by sliding them to the right by varying degrees. With a little quick experimenting, it is pretty easy to find the distances from the original track to create delays in whatever pattern you might want. Many delay processors will sync their echo in time to the song's tempo — and that's cool — but by dragging clones of a track manually, you can do rhythmic figures that have more of an old-school DJ scratching feel, where the repeats are a unique rhythmic phrase in and of themselves. Once you become comfortable with moving copies of a track around and see how the offsets result in different delay effects, you will develop a visual sense of time and amplitude that will help you internalize and understand more deeply the concept of what a delay effect does.
A SWEEPING CONCLUSION
If you apply filter sweeps, phase shifting or flanging effects to an ambient-processed signal, you will find that the results are quite different between processing a series of delays versus a reverb tail. While a reverb provides a consistent tail to sweep through, a series of discrete delays can jump out across a sweep in satisfying ways as well, reminiscent of a great sample-and-hold synth patch.
As always, the ideas presented here are meant to help you understand the tools you have better, and to help you be comfortable and confident to boldly go where no remixer has gone before.
The Waves TrueVerb ($200 native/$400 TDM; www.waves.com) plug-in is my favorite for creating one of my all-time favorite ambient effects, which I call the “invisible room” reverb, because unlike some reverb algorithms, it is possible to shorten the reverb decay time to around half a second or less without having it get all metallic-sounding and weird. Notice that the decay time is set to 0.6 seconds. Basically, the idea is to create an ambient reverb setting that is never noticed as such, but which adds very intriguing and enticing depth and aura to a lead vocal or key instrument. In conjunction with judicious compression, the “invisible room” places your lead vocal naturally in the front with an undefinable glow, and if you can tuck it just below recognizability as an ambient effect, it shows up on the listener's somatic radar but remains enigmatic.