Read part one of Paul White’s article on effectively using reverb here.
Gated and reverse reverb
Gated reverb was first created by putting mic’ed room ambience through a noise gate, the most common example being the big Phil Collins drum sound. The effect is easily faked digitally by creating a dense burst of early reflections at a more or less constant level, then cutting these dead after half a second or so. While the gated drum sound is a little dated, using the effect at a lower level can still add energy to drum and electric guitar sounds. It also has the advantage that it doesn’t fill up all the space in the mix with a reverb wash.
Reverse reverb is very similar but instead uses a pattern of early reflections that starts off low and then increases in level before stopping abruptly. This gives a nice reverse character to the reverb envelope.
Interestingly, though some of the early digital reverb units didn’t sound entirely natural, they did posses a certain musicality, which is why there are many plug-ins available to emulate these older devices. Sometimes the sound of a real room, or a perfect emulation of one, is just a little bit too real!
As reverb is rarely used without some of the original sound being present, the device or plug-in will probably have a wet/dry mix control, though if you’re using reverb in an aux send loop, then it should be set to ‘wet only’ as the dry part of the sound comes via the mixer channel. The outputs from the reverb are normally panned hard left and hard right to create a sense of stereo spread.
While a channel insert point can be used to add reverb to a single instrument or voice, this is a wasteful approach if several tracks in your mix need to the same type of reverb added to them. Using the aux sends allows one reverb unit or plug-in to be shared between as many channels as need it. You’ll find many reviews of reverb hardware and plug-ins on the soundonsound.com web site as well as several articles dedicated to setting up and using reverb within a mix.
Today we have traditional algorithmic reverb, which has the benefit of being very adjustable, but we also have what is known as Convolution reverb where impulse measurements are taken in real spaces and then transferred to your own audio file using a reverb unit or plug-in designed for the purpose. Convolution takes even more number-crunching power than algorithmic reverb but the advantage is that you can choose from a library of impulse responses (IRs) taken from real concert halls, churches, cathedrals, recording studios and night clubs and then apply them to your own tracks. The best-known convolution plug-in reverb is probably Altiverb from Audio Ease though Apple’s Logic Pro DAW software comes with the Space Designer convolution reverb already built in. Some reverb units also combine both approaches (including later versions of Altiverb) where the convolution process provides the first part of the reverb and algorithmic reverb provides the tail. The advantage is that the reverb tail can be adjusted over a wide range and the demands on the host computer are also a little lighter.
Reverb can be applied to any sound that you think needs it though beware of overdoing it as excess reverb fills up all the spaces in a track making it sound messy. Most vocal tracks benefit from a subtle application of reverb as do drums and other acoustic instruments recorded in a very dry acoustic. A typical mix session will utilise two or maybe three different reverb units or plug-ins, each with different settings. A typical approach is to set up a short reverb to add a subtle natural ambience and perhaps one or two longer ones to use on specific instruments and voices. Plate emulations remain popular as they add the necessary gloss to the sound without suggesting a particular type of acoustic space.
Kick drums and bass instruments are, however, best left fairly dry to avoid muddying the bass end of the mix, though in some situations a short ambience treatment may work well to help glue them into the rest of the mix. A common ploy is to use EQ (or the internal EQ controls in the reverb plug-in) to thin out the low end below around 200Hz as this helps keep the lows clean and focussed.
Vocals invariably sound better with reverb than without it, though having said that, today’s mixes often use far less reverb than was the case during the 70s and 80s. Subtle reverb combined with low levels of echo/delay is a common treatment but always judge the level in the context of the entire mix as what sound like too much reverb when you solo a track may sound like too little when everything is playing together.
It is also worth experimenting with different effect combinations such as placing a flanger or chorus before the reverb unit (when feeding it from an aux send) but leaving the dry part of the sound unaffected. Another neat trick is to use a pitch correction plug-in such as Autotune before the reverb and set its correction speed to fastest. On its own this produces the familiar vocoder-like effect heard on countless pop records but when used to process only the feed to the reverb, it adds a nice richness and complexity to the overall sound without making your vocal sound overprocessed.