Time Based Effects

Creating & Using Custom Effects If I had to pick a single desert island effect, it would be delay. Why? Well, delay isn't only an effect in itself; it's also one of the basic building blocks for many other effects, including reverb, and — and that makes it massively versatile. The aim of this article is to focus on the practical applications of delays, by looking at some ways they're typically used on vocals, guitars and synths. I'll be writing primarily about the sound of different delay configurations.

First, let's run through a quick overview to get any newbies up to speed. As the name suggests, the way in which delay processors work is quite simple: the programme material passes through a memory buffer and it is then recalled from the buffer a short time later. We refer to this time difference as the delay time. (In an analogue delay, you could think of the electronics or the performing the same function as the memory in a digital delay.) Multiple echoes or 'repeats' of the programme material are produced by feeding a percentage of the delayed material back from the output of the delay buffer into the input. We refer to this as feedback. You should be aware when adjusting the feedback parameter that high settings can result in the level of the processed signal increasing rapidly with each repeat, so if your monitoring levels are high, it pays to be careful!

As with reverb, delay is most often applied as a send effect, rather than as an insert. This approach not only conserves processing power when applying the same delay to multiple sources, but it allows you to treat the delayed part of the signal, separately from the original, with extra processing such as EQ or distortion and this allows you more creative freedom.

That's it in a nutshell, but the combination of those few parameters and the flexibility afforded by using delays as send effects open up a world of production effects and tricks. With the basics explained, let's work through some useful techniques.

Vocal Treatments During the mix process, vocals are often treated with either reverb or delay, or possibly a combination of both, so in the following section I'll work through some typical vocal delay treatments. To get the most from these, call up a vocal part of your own in your DAW and use that as raw material. For my examples, I've taken a heavily 'tuned' vocal with a tempo of 130bpm (audio examples 1 and 1b).

1. Create a send from your vocal track and on the send, call up a delay plug-in. It doesn't need to be a sophisticated one; in fact, the simpler the plug-in is, the easier this will be to follow. I'm working in Logic Pro here, and I've used Logic's Tape Delay. 2. Set the delay time to a quarter note and the feedback to zero. If you're using a delay that doesn't have tempo-sync options, you can still get things in sync by remembering the following equation: ms = 60,000 ÷ bpm. Note that 'ms' is the quarter-note delay time in milliseconds, 60,000 is the number of milliseconds in a minute, and 'bpm' is the tempo in beats per minute. From there, you can divide the result as necessary to get eighth notes, sixteenth notes, and so on. 3. With the vocal playing, gradually raise the send amount and you'll hear a single quarter-note echo that, when set quietly, can add a useful sense of ambience to a vocal. 4. Next, gradually raise the amount of feedback until the delay fills up the gaps between the vocal phrases, but doesn't cloud over the original (audio example 2).

EQ’ed & Distorted Delay With the quarter-note delay in place, it's common to try to create a unique 'space' for the delay in the mix, and this can often be accomplished by applying EQ before or after the delay (it doesn't normally matter which, though there will be subtle differences in, for example, the response of a tape delay to a signal with the low end present and the low end filtered away). As Robert Orton, discussing his mix of Lady Gaga's 'Just Dance' in SOS March 2009 explained, what EQ settings you require will vary from mix to mix: "Sometimes you want quite a dark delay that's hidden behind the vocals just to give it more body; at other times [there's] a word that clearly repeats, in which case the delay has to sound up-front and clear”.

A simple quarter note delay in Logic Pro's Tape Delay plug-in.

Many plug-in delays have in-built high- and low-pass filters, but don't worry if yours doesn't, because you can use a separate EQ — as in this example: 1. Find an EQ plug-in that includes high- and low-pass filters and place an instance of it after your delay. 2. Start by rolling off the high frequencies of the delayed sound, using a low-pass filter. This will soften any transients, and help to push the delay back in the mix behind the main vocal sound. When used at low levels, this creates a really subtle sense of ambience. 3. Now bypass the low-pass filter and try high-pass filtering the delay, to remove some of its bottom end. This can help to stop the delay clouding up the low end of your mix. 4. Finally, combine the high-and low-pass filters to create a 'telephone' EQ. This effect (see image 2) is much less obvious when used on the delay signal than on the source vocal track, and it's a tactic that can reduce the amount of space taken up by the delay, leaving space for other elements. It also helps to make the delay more distinct from the original vocal (audio example 3).

You can find another example of this last effect in Peter Mokran's Mix of the Pussy Cat Dolls track 'Jai Ho!', where he inserted the telephonic EQ before the delay.

'Telephone EQ' can be applied before or after the delay effect to differentiate the echo from the original vocal.

One reason for using a delay instead of a reverb for these treatments is that quarteror eighth-note delays are heard distinctly from the original vocal, whereas with a reverb, the early reflections can easily combine with the original vocal part and thus change its perceived timbre. This means that, for example, adding a bright quarter-note delay doesn't brighten the original vocal in the way that adding a bright reverb might do.

Another way to make the delayed signal stand apart from the original vocal is to run the delay through an amp and/or speaker simulation plug-in. The plug-in will not only provide a unique equalisation curve, but the sound of the speaker and the distortion from the amp will add a compression effect that can help to even out the level between repeats. This adds a greater sense of sustain to the delayed signal. It's worth experimenting with different amp models and cabinets, as you'll find plenty of different timbres. There really are no hard and fast rules as to what works best here.

Repeat After Me… Now let's set up a second send, this time with a eighth-note delay. Again, there are plenty of plug-ins you could use, and I'm going to choose Soundtoys Echoboy, which is a really versatile plug-in. It has low- and high-pass filters and, in the Style Edit section, further equalisation and output-modelling options. This allows you to do all of the tonal shaping we've just discussed inside a single plug-in, and this means that you can quickly compare radically different delay, equalisation and distortion settings simply by changing presets. Echoboy also has a Decay EQ section, which is an EQ that's placed in the delay's feedback loop, and thus allows you to make each successive repeat duller or brighter, making the delay evolve in timbre with each repeat (audio example 5). In simpler terms, this feature controls how the tone of the echo changes over time.

The comprehensive EQ and output modelling section in Sound Toys' EchoBoy allow the user to compare drastically different delays simply by changing presets.

There are plenty of other plug-ins that offer this sort of feature, and it's well worth having one in your mix toolkit, as it's often tricky setting up an EQ'ed feedback signal using separate delay and EQ plug-ins, partly because not all DAWs have sufficiently flexible routing.

Ducked Delay With conventional delay setups, it can sometimes be difficult to find a constant send level that allows the delay to be sufficiently audible when the singer finishes a word, but doesn't cloud the vocal when he or she is singing. To counter this problem, you could use automation to ride either the send or return level of the delay on the offending passages (better to automate the send if you're sharing the delay with other sources). This has the advantage of giving you absolute control over the level of the delay, but it can be fiddly, particularly if you need to go back and change this automation as your mix evolves.

A less fussy means of achieving a similar result is to set up a compressor to duck the delay when the vocal is present. To set this up, you'll need a compressor and DAW that allow you to use an external side-chain input. Here's how to do it: 1. Add the compressor after the delay — and any subsequent processors in the send chain — on your send channel (screen 5). 2. Next, go to the compressor's side-chain input and set it so that the compressor is triggered by the lead vocal track. How you do this varies from DAW to DAW, so if you're unsure, check the manual. 3. With the track playing, lower the threshold and raise the ratio to apply the appropriate amount of gain reduction to the delayed signal (audio examples 6 and 7).

The setup in Logic for creating a delay. I've used Logic's Compressor plug-in to provide the ducking but I could just as easily have used the included or Ducker plug-ins, shown bypassed.

This is a common but effective trick, which has been used on plenty of hit records. By way of example, Marcella Araica used this on Timbaland's 'The Way I Are': listen to that track, and you'll hear the delay become prominent after the last lines of the verses.

Delay Versus Reverb When you're mixing, one of the advantages of using a simple quarter-note delay on a vocal is that, compared to reverb, it takes up such a small amount of space in a mix, and this is even more the case when you use a mono delay. By combining a single quarter-note mono delay with a lead vocal that's also mono, you can preserve the positional integrity of that source. This can be helpful in busy , where space is at a premium.

Mixing isn't always about saving space for other elements, though: in a spacious mix, you might actually want the vocal effects to take up more room, and in this scenario it's a good idea to look at creating a sound using both your delay and reverb plug-ins. Running a delay into a stereo reverb will spread the delay out across the stereo field, making it seem broader (audio example 8a). One trick that's well worth exploring is running your delay through an early-reflection patch from a reverb, as this will 'stereoize' the delay without it sounding so obviously affected.

You can also use both your mono delay and stereo reverb to deliberately create contrast between song sections. For example, you could use a quarter-note delay on a mono verse vocal to add a sense of ambience while keeping things dead centre, but follow this in the chorus by moving to ultra-wide stereo vocals, with stereo delay and reverb effects. It's this sort of contrast that's so essential in keeping the listener's ear engaged. When processing a lead vocal, then, consider in all of the different song sections whether you want both the vocal track and its send delay and reverb effects to sound more mono or more stereo.

A delay can also be used to change the character of a reverb, by acting as an ultra-configurable pre-delay. If you listen to audio example 8c, you'll hear that the vocal is treated with a small amount of hall reverb. Then listen to example 8d, where I've taken the same reverb but inserted an eighth-note delay (with feedback set to zero) before the hall reverb: the delayed reverb seems louder and more obvious in the mix. Even though many reverb plug-ins have a pre-delay control, they're often not tempo-syncable, and that's why I prefer to use a dedicated delay plug-in to provide the pre-delay: most delay plug-ins offer tempo-sync'ed delay times at the click of a button. Thus, I'm able to quickly compare say a sixteenth-note or eighth-note pre-delay.

Ping-Pong Delay Ping-pong delay is a type of dual delay where the first echo appears in the 'ping' channel (usually the left), delayed by the ping amount, and the second appears in the opposite 'pong' channel, delayed by the ping time plus the pong time. For example, if you set the ping to 200ms and the pong to 400ms, you'd first hear the ping 200ms after the programme material out of the left channel, and the Pong 600ms after the programme material out of the right channel. This process will then repeat, assuming the feedback values are higher than zero. In audio example 9, Echoboy is set to a ping-pong delay with the Transmitter output style, to give a telephonic effect.

A ping-pong delay.

On his mix of U2's 'No Line On The Horizon', Declan Gaffney used the SoundToys Echoboy plugin to add a subtle amount of ambience to the lead vocal using a ping-pong setting: "The echo is just a kind of warm ping-pong sound. There's no reverb on the track, there's not even any feedback on the delay, it's all about the dry sound with of space on the side, provided by the delay… I'm not a huge fan of reverb anyway; it's better to do the same thing with delays.”

Slap Happy I'm not sure if there's an official definition of 'slapback delay' as an artificial effect, but it is generally used to describe a single echo of 60-180ms that creates a sort of thickening effect. Famous fans of slapback on their voice include and Elvis Presley. 'Slap delay' like this is also a standard treatment for hip-hop vocals because, as Jaycen Joshua put it in SOS

Slapback delays were originally created with tape machines, so you may want to try rolling off a little of the top end and adding a small amount of modulation of the delay time to approximate some of the inconsistencies of tape. It's also fun to try a stereo slapback delay using a dual delay with slightly different delay times for each side, as this will create a wider stereo image. Audio example 10b is a slapback delay with the left side set to 80ms and the right side set to 120ms: listen out for the extra stereo width this gives the vocal.

I'll mention one last slap-related trick before we move on: take a short slapback delay and then gradually increase the feedback. Because of the relatively short delay time, this will begin to sound reminiscent of a spring reverb, such as you often find in guitar amps.

Stereoising A Delay The German scientist Helmut Haas wrote that when two identical signals, each played through a separate speaker, are delayed by anything from 1-30ms, a sense of a broadening of the primary sound source is heard, but without there being a perceptible echo. This effect, often referred to as the 'Haas effect', can be created using delay plug-ins or track offsets, and can be used to add stereo width to a vocal part. It also serves as a reasonable foundation for creating fake double-tracking effects.

Let's look at some settings. If you take a delay plug-in and increase the right channel's delay time to 10ms more than the left, you should notice that the delay creates a stereo effect rather than a perceptible echo: the delay simply broadens the vocal, adding stereo width.

Using a plug-in like Logic's Sample Delay can create extra stereo width, but often at the expense of mono compatibility.

Jaycen Joshua used this type of processing to create a stereo effect for the crash cymbal on Justin Bieber's 'Baby': "There's a medium delay on the crash,” he remarks, "because it was originally a mono track, and I wanted it in stereo. So I set the delay to 21ms and mixed the original 100 percent to the left, and the delay to the right…. With 21ms, you get enough separation between left and right and it's a bit dramatic and not so phasey.... The sound becomes like a drummer hitting two cymbals, left and right, at the same time.”

Unfortunately, though, this approach can create problematic side-effects. First, simply delaying one side in relation to the other will result in unpleasant comb filtering when the left and right channels are summed to mono. Example 11c shows the effect of making the delayed vocal mono. Contrast that with example 11a and you'll hear why this sort of processing is risky if you want to ensure mono compatibility! A second problem with this treatment is that you can perceive that the undelayed side as louder than the delayed side, causing potential balance problems.

To take advantage of the widening effect that Haas delays offer, while deftly dodging the monocompatibility trap, there are some useful tricks. One of the most common widening treatments is created using two short delays, with a small amount of pitch-shifting applied to either side. To achieve this effect yourself: 1. Set a mono delay to 11ms and with zero feedback, then pan it hard right. 2. Then, add a pitch-shift plug-in to take it up seven cents. Repeat this with a second delay, but this time pan it hard left, and pitch-shift it down by seven cents.

The classic delay/pitch shifted widener: an incredibly useful effect, heard on many chart hits.

To create these, I've used Logic's Delay Designer plug-in (screen 7), as it allows you to set up multiple delays and pitch-shifting all in the same plug-in, but it's easy enough to do by combining delays and pitch-shifters separately. If you want to hear the effect used in context, there are countless commercial tracks I could offer by way of example, one of which is the Arcade Fires album The Suburbs. Producer Craig Silvery explained in SOS November 2010 that he used "two short delays from an AMS with a little pitch-shift, one up and one down, which thickened the vocals like a doubler.

A nice variation on this effect is provided by Waves' Doubler plug-in, which provides the same widening effect but with a less obviously effected sound. In the words of Grammy-winning mix engineer Dave Pensado: "Doubler has four delays that also help to make the vocal sound bigger, wider and more powerful”

Very short ping-pong delays can also make excellent wideners, as you can hear if you listen to audio example 11g, which shows a 30ms ping-pong delay built with NI Reaktor, where the output of the ping delay is polarity inverted before going into the pong delay. This technique is great for transparent widening and has excellent mono compatibility.

Consecutive delay taps panned left and then right to create an effect similar to reverb.

Multi-Tap Delay A multi-tap delay is a delay line where multiple 'taps' or outputs are taken from a delay buffer at different points, and the taps are then summed with the original. Multi-tap delays are great for creating rhythmic delay patterns, but they can also be used to create sound fields of such density that they start to take on some of the qualities we'd more usually associate with reverb. Favourite plug-ins for the job include Waves Supertap, PSP Audioware's PSP608 and Echoboy, using its Pattern mode, but there are many more available, and you might even have suitable toys bundled with your DAW (I often use Logic's Delay Designer, for example).

In this screen, the delay taps are being increasingly high- and low-pass filtered the longer they get.

It can be great fun using a multi-tap delay to design reverb-like effects that, while they might not compete with a proper reverb algorithm in terms of realism, can produce some wonderful, unique-sounding results. A simple method for creating a reverb-like setting is to take a multitap delay and create a series of delay taps starting at 30ms and increasing in time. With the preset shown in screen 8, I've gradually increased the delay tap times in Logic's Delay Designer at random up to the last taps, which are in time with the sequencer tempo, the last tap being a quarter-note delay. To build on this starting point, experiment with panning successive delay taps left and right, filtering the delay taps so that each tap becomes duller, and changing each tap's volume.

Dave Pensado describes how he used the Waves Supertap plug-in on the lead vocal for the track 'Beep' by the Pussycat Dolls: "The delays on Supertap are all very short, and what it also allowed me to do is spread the vocal wide across the stereo spectrum. In other words, instead of occupying a small spot in the middle of the mix, I could fill the whole spectrum between the speakers. The 149, 298 and 587 ms are sixteenth, eighth and half-note delays, and they spread and get louder from left to right." If you have Supertap in your plugin collection, you can find a similar setting to the one used for 'Beep' in the preset menu under Dave Pensado/Pensado Tap Vocal.

Automation Of course, you don't have to use just one delay effect on a sound. It's perfectly possible to set up a range of different delays on your aux send channels, and then experiment with automating different delays on different words. It's this level of sophistication you might need to reach for if you want to compete with contemporary pop tracks.

For example, in SOS March 2009 (/sos/mar09/articles/it_0309.htm) Robert Orton described how he automated the delays on Lady Gaga's hit 'Just Dance': "When soloing the vocals, I added half-, quarter- and eighth-note delays, and I think there's also a dotted eighthnote delay, all using the Sound Toys Echoboy… The eighth-note delay is panned to the right, and comes in the choruses and some words in the verses. The send is automated. The halfnote delay is panned to the left, and captures certain words; for instance, in the chorus each time the word 'dance' occurs at the end of a line. The quarter-note delay is also panned to the right, and is automated to happen on certain words. All the delays catch words differently, to keep it interesting. They're also set to different styles on the Echoboy — TubeTape, Analogue, etc — to get different textures.”

Use Reverb Like A Pro Reverb and delay are arguably the most common effects used at mixdown, but because they find so many different uses in this context they can seem bewildering to musicians who are still in the process of getting to grips with the fundamentals of studio production — those setting up a home studio, perhaps, or those enrolled in a music technology course for the first time.

Part of the problem inevitably stems from the wide range of different devices available that can supply these types of effects, and from their frequently inscrutable editing parameters. There is, however, an enormous amount of information on hand to demystify such technicalities, not least in Sound On Sound 's online article archive. Furthermore, the preset-led nature of many effects units these days makes it unnecessary for the beginner to delve very far into their algorithmic innards, and to be honest I think there are quicker results to be gained at the outset by working from presets, and leaving most of the effects parameters well alone!

As I see it, the more pressing difficulty when starting out is dealing with basic practical questions such as how many different effects to use, which effects to apply to which instrument, and how to decide on suitable levels. So in this article I'll be trying to eliminate some of the guesswork by suggesting a basic general-purpose approach to using reverb and delay while mixing. In the process I'll pinpoint some things to watch out for when surfing reverb presets, as well as highlighting the handful of effects parameters and techniques that make the biggest impact with the least effort.

However, I've always felt that there's only so much you can communicate in print alone when you're dealing with mixing techniques, so I've also put together a bunch of audio examples so that you can judge for yourself how useful each of my proposed methods is in practice. You can download them in MP3 or WAV format from the SOS web site at www.soundonsound.com/sos/ jul08/articles/reverb1audio.htm. ​

On the most fundamental level, both delay and reverb are about adding the characteristics of an acoustic environment, either by creating simple echoes or by simulating more complex patterns of sonic reflections. The reason these effects are usually so important at mixdown is because the individual parts in most modern multitrack projects communicate very little in the way of a common sense of space, and as such sound a bit 'dislocated', rather than seeming to belong on the same record. Obviously, synthesizers and sampled sounds often have no sense of acoustic realism to them at all, but even miked instruments are often recorded very close up, to reduce room reflections as much as possible, allowing decisions about the nature of the production's overall acoustic space to be deferred until the final mixdown.

For this reason, the primary objective of reverbs and delays is to reconnect tracks that have no inherent connection by giving them some shared acoustic characteristics, and it's this task that's the subject of the article at hand. Naturally, there are creative applications of reverbs and delays too, but these are window-dressing in most mixes (as well as being very much more a matter of personal taste), and will do your mix little good if the main edifice doesn't really cohere properly.

Send Effects & Mix Balance Because the underlying aim is to give the separate tracks something in common, it makes sense to set up your plug-ins or hardware processors so that the same effect can be applied to multiple tracks at the same time. Whether you're using a hardware or a software mixer, the manner of doing this is pretty much the same. First of all you set up the output of your effects processor to feed a spare stereo mixer channel; then you set up a separate mix of your tracks specifically for the effects processor and send it to the unit's inputs, whereupon the affected signal feeds back into the mix. By changing the levels of the different tracks in the send mix, you determine how much of the effect is added to each track.

In hardware systems, the mixer will have auxiliary send controls which allow you to create a number of independent effects-send mixes, each mix appearing on a separate output socket. By connecting different effects units to the mixer's different auxiliary-send outputs, you can drive several independent effects at once, assuming that you have enough free mixer inputs through which to return their outputs. In software, a separate mixer channel usually needs to be created to hold the effect plug-in, whereupon auxiliary sends can be created on each relevant mixer channel to feed it. (This is exactly the kind of setup I used in Cockos Reaper to create my audio examples, using a section of an otherwise dry multitrack project.)

Irrespective of which kind of system you work in, though, there are two important things that you need to bear in mind if you're going to ensure that this kind of effect configuration (usually called a 'send effect' or 'effect loop') works properly. The first thing is that you need to make sure the processors or plug-ins you're using only output effects, not a mix of processed and unprocessed signals, otherwise changing any auxiliary send level will also have an impact on that track's overall volume. Some effects units have separate level settings for effected ('wet') and uneffected ('dry') signals, while others offer a Mix Balance control, which needs to be set to one extreme (usually labelled something like '100 percent wet') to stop any unprocessed signal breaking through.

The second thing to ensure is that each channel's auxiliary send is taken from a point in the signal path after the channel's fader — in other words, that you use what is called a 'post-fade' auxiliary send. That way the amount of effects for any instrument will vary naturally as its channel fader is moved. If you fed the auxiliary send from before the fader, then you could, for example, fade a track completely down and you'd still be hearing its reverb — rarely a desirable state of affairs except for the occasional special effect.

Choosing Reverb Presets Now that we're clear on how to set up the necessary connections, it's time to start considering the effects themselves. First of all, let's start by looking at how you can use just reverb to draw a final mix together, and then we'll build on that to show the subtly different possibilities that are afforded by delay effects.

As I've already mentioned, there are enough things for newcomers to mixing to worry about without programming their own reverbs from scratch, so I would certainly recommend starting from presets where possible. However, this tactic only lets you off the hook to a certain degree, because it's still up to you to select the right processor and preset for the task. Here are a few tips.

The first, and probably most useful, thing I can say is that you should ignore the preset names and instead try to imagine the kind of space you want your mix to inhabit — picturing a real environment can help focus the mind here, although this may not help as much if you're trying to create a more other-worldly sound. A wrong choice in this regard can be almost impossible to sort out during mixing, whereas a reverb with the right kind of inherent acoustic signature but the wrong tone and/or length can usually be tweaked into better shape comparatively easily. It's not uncommon for me to wade through a couple of dozen presets before I find one that instinctively feels like it fits the mix in hand, and it's vital that you don't hurry this process.

Beyond that rather intangible decision, though, there are a few other more down-to-earth things to consider. First of all, if you have a choice of reverb processors or plug-ins, be wary of any that produce a metallic sort of sound, particularly in response to noisy tracks like drums. To show what I mean by this, let me turn to the first of my audio examples: the Reverb1 and Reverb2 audio files. The former has a pronounced metallic ring to it, whereas the latter (while still far from perfect) is a bit better behaved in this regard, and is likely to prove much more usable. The problem with metallic resonances is that, by the time the reverb is at a level where it's doing its job, the overtones become too clearly audible, unpleasantly colouring the mix as a whole and making the effect sound too obvious. Reverbs with obvious resonant 'character' do have their uses at the mix, but typically for other, more specialised tasks beyond the scope of this article, so it's best to steer clear of them to begin with. (It's worth pointing out that the Reverb1 file also veers off to one side of the stereo image as it decays, which isn't ideal either.)

Another basic principle when looking for reverbs that will bind a mix together is to tread carefully with any that seem to have very prominent frequency extremes. Neither very high frequencies nor very low frequencies are much use when using reverb to bind a track together, the former tending to make the reverb too audible in its own right, and the latter reducing punch at the low end of the mix where definition is normally really important.

Tweaking Reverbs: The Controls To Reach For First If you're lucky, you might have selected a reverb preset that's perfect for your track. In my experience, though, no preset ever seems to fit the mix like a glove, and I routinely tweak the reverb sound in a variety of ways while mixing, to make it match better. What I also find is that amongst the forest of reverb parameters frequently provided, some end up being much more useful than others, so here are a few pointers for getting the quickest results.

The most important thing that you need to get right is the balance between the length of the reverb and its overall level across all the tracks in the mix. Most people who send mixes in for Mix Rescue tend to have misjudged this balance, either by having the reverb too long, so that they can't fade it up far enough without it washing out the whole mix, or by having it too short, so that they can't get a full sound without distancing their tracks to the horizon. Almost every reverb processor has some kind of control to change the length of the reverb (often labelled Decay Time or Reverb Time), so one of the most important things you can do is to experiment with different reverb length settings, juggling the return channel's fader in tandem, to find the best balance between these two parameters. In fact, this is something I often find myself coming back to late in the mix, as it can be difficult to judge properly until the comparative reverb levels for all the instruments are set up.

If you have a listen to the ReverbLength audio files you can hear how the length of a single reverb can affect the fullness of the mix, given a fixed effect-return level. ReverbLengthShort leaves the mix a bit lacking in warmth, while at the other extreme ReverbLengthLong goes over the top, swamping the details in the mix and giving itself away as an unnatural effect. ReverbLengthMedium strikes a balance between these two extremes and therefore sounds more successful in context. I've also created a file of the same section with the reverb bypassed so that you can hear how it's contributing to the song's blend. (Incidentally, If you're having difficulty initially distinguishing the differences between the different sets of audio files, try importing all of them into your own sequencer so that they're all playing back at once, and then use your mixer solo buttons to switch between them while they're playing. This makes subtle adjustments between the files much more apparent.)

The next most common thing I do with any reverb is adjust its tonality to suit the track. Some equalisation controls are often built into the reverb processor, but I usually prefer the extra flexibility afforded by a separate equaliser following the reverb in the return channel. With modern commercial styles I almost always cut away some of the low frequencies with a highpass filter set somewhere in the 100-300Hz range, simply because it allows me to keep the required focus and punch of kick drums and bass lines uncompromised. I also often cut high frequencies as well, either with a low-pass filter or high shelf. This is partly because it helps make the reverb less audible as an added effect (particularly in response to vocal consonants and high percussion), but also partly because it has the psychological effect of making the reverb seem further away from the listener than the brighter dry sounds.

However, in addition to cutting high end and low end, it can also make a great deal of sense to sculpt the reverb return's tonality even further if you find that it's colouring the mix's overall tone undesirably. Another reason for doing this is that the fashion these days is for reverb to be pretty inconspicuous, but it still needs to be high enough in level to get the instruments to gel properly. If your reverb has a prominent frequency-response peak where little else is happening in your mix, this will make the too audible well before the overall reverb level is high enough. A few well-placed reverb-return EQ cuts once the mix is up and running can therefore really pay dividends if you're after an up-front production sound that is nevertheless still cohesive.

To demonstrate the impact of these kinds of EQ changes, I used the same reverb effect from the previous example, on which I'd already used all the types of EQ I've been talking about, to create the ReverbEQFull audio file. I then dropped out each of the three filter bands (a highpass filter at 240Hz, a very gentle low-pass filter rolling off from around 7kHz, and a 5dB peaking cut over a one-octave band at 580Hz) to generate the ReverbEQHPFOut, ReverbEQLPFOut, and ReverbEQPeakCutOut files.

The final reverb parameter that I regularly reach for is the pre-delay setting, which simply delays the onset of the reverb reflections by a specified amount — the longer the pre-delay, the closer the dry sounds appear to be in comparison with the boundaries of the simulated room. Some reverb plug-ins either have no pre-delay option or have a zero default setting, and if left unchanged this psychologically positions any sound source much further away from the listener, effectively right against one of the boundaries of the simulated room. This isn't the only problem, though, because what also happens is that the almost instantaneous early reflections of a reverb without pre-delay interact unpredictably with the dry sound in a way that can noticeably alter its tone. An immediate reverb onset can interfere with vocal intelligibility too, by blurring important consonants. Again, Mix Rescue candidates regularly encounter all these difficulties, simply because they ignore the pre-delay setting — and even if your reverb has no internal pre-delay, that's no excuse not to dial one in manually by chaining delay and reverb effects in series.

To hear how audible these factors are in practice, try comparing the ReverbPredelayIn and ReverbPredelayOut files. The first of these uses a 35ms pre-delay, while the second has none at all. To my ears, the vocalist takes a clear step backwards when the pre-delay is bypassed, and sounds less clear into the bargain.

The Long & The Short Of It On the face of it, if you're trying to get your tracks to sound as though they're all roughly in the same space, sending to a single global reverb from all of them is a common-sense approach. However, in my experience this puts a lot more pressure on the engineer to select and tweak that single reverb to get respectable results, so I usually suggest to those starting out that it's actually easier if they use two. Let me explain how this works.

The idea is that the two reverbs each serve different purposes, and they can be mixed and matched to cope with a range of recording types within most typical projects. The first reverb is short (usually well under a second in length) and with perhaps only 5-10ms of pre-delay. What this does is simply make disconnected sounds stick together more convincingly within the mix, as well as setting the distance between these sounds and the listener, but without making itself obviously audible as an added effect, given its minimal reverb 'tail'. (As a result, some engineers call this effect ambience rather than reverb.) The second reverb can then be set to give much more of a sense of an acoustic space, using a longer and perhaps slightly brighter reverb as required, but combining that with a fairly long pre-delay (maybe 30-70ms), to avoid the effect distancing sounds that it's applied to very much further.

Having these two reverbs on hand, you can then deal with a variety of different situations. For example, a bone-dry synthesizer track that belongs in the track's background might need lots of short reverb to push it away from the listener, whereas a lead vocal might only have just enough to make it sound as if it belongs in the mix — indeed, it might have none at all if you want to achieve the most upfront sound, albeit at the risk of it sounding disconnected from the record as a whole. Both of the tracks may need a bit of the longer reverb, though, if you're trying to make them sound natural together.

To take another example, drum overhead mics that already have a lot of room sound on them could easily warrant no added reverb at all (although you might try to match the sound of the longer reverb to them somewhat, to get other, drier sounds to work alongside), but some of the accompanying close mics may benefit from some of the shorter variety, to avoid them advancing too far forward in the mix perspective. A retriggered drum sample, however, would probably need both reverbs, carefully applied, to blend it convincingly with the rest of the kit: the shorter reverb would primarily set its distance, while the longer could help to retrospectively teleport it into the original recording room.

Clearly, both of your reverbs will need to be tweaked to suit the track, but as long as you stay focused on their respective purposes you shouldn't go too far wrong. If the shorter reverb can't blend tracks together before it becomes too audible, try further reducing its reverb time or dial in some EQ cuts on the reverb return channel. If the longer reverb is making things sound distant, you can take off some high end to push it further into the background; if it's making things sound woolly, adjust that level/length ratio or crank up the return channel's high-pass filter.

To demonstrate this dual-reverb setup in practice, I've done a rough mix of the chorus of my little demo project using just these two effects, to create the DualReverbsBoth file, but I have also then made two further files (DualReverbsShortOnly and DualReverbsLongOnly) designed to show what each effect is contributing in isolation. The DualReverbsDry file, as you might expect, is the same section without any reverb at all, just for reference.

How Musc On Which Instruments? Many people eschew reverb on kick and bass entirely, to avoid low-end mush, but there's no need to be hard-and-fast about this and risk throwing the baby out with the bath water. If a little reverb helps to achieve a more satisfactory blend of these instruments with the rest of the track, it's no bad thing, just as long as you keep any undesirable bass overhang in check with your return-channel EQ.

One type of track that I rarely put reverb on, though, is any background synth pad I might be using. These invariably sink into the track without any extra help, and because they already tend to create a homogeneous blanket of sound, even large amounts of reverb will seldom be noticeable — all the reverb does is make the part sound ! If a synth pad is too far forward in the mix, a more effective recourse is to just shelve off a bit of high end with EQ.

Probably the most important thing to say about using any reverb, though, is that it's not a bad idea to err on the side of using too little in general, particularly if you anticipate using -style dynamics processing on the final mix at a later stage, because this will tend to increase the levels of mix details such as reverb tails. In a lot of cases where an obviously reverberant sound isn't required, it's quite a useful little rule of thumb to set levels so that the reverb only really draws attention to itself if you mute the reverb return — that way you can be pretty sure it's only supporting, rather than overwhelming, the dry tracks.

When you're trying to finesse reverb levels in your track, another handy trick suggested by top engineers such as Geoff Emerick and Alan Parsons is temporarily to mute the most prominent tracks in the mix, typically drums, bass, and/or lead vocal. This lets you hear more clearly whether there are any less-than-ideal reverb balances amongst the background instrumentation.

Blending Your Mix With Delay Effects Instead Delay is a much simpler effect than reverb; most of the time you can pretty much set the delay time (the distance between the echoes) and the feedback level (the number of echoes) and you're off! Perhaps it's because of this simplicity that so many musicians ignore it when it comes to the mix, or maybe it's just that they don't want any kind of distracting 'echo effect'. This is a shame, however, because delay is almost as useful as reverb when it comes to gluing instruments together at mixdown. In fact, in some senses delay is superior to reverb for many dry-sounding modern styles, as it can achieve cohesion without any obvious reverb tail, leaving individual sounds more upfront, distinct, and raw-sounding. It also tends to leave the mix sound much clearer, because it doesn't fill up all the gaps in the stereo field in the way reverb tends to.

Although there are many uses for mono delays, if you're looking to use delay effects for subtle blending tasks, you'll get the most transparent results if you use them in stereo, such that if you send any panned or stereo tracks in your to the delay channel, the echoes return with the same stereo positioning and spread. This can be fiddly to manage in hardware setups, even if you have a stereo delay unit, as very few mixers have stereo sends, so you may need to carefully juggle the levels of two separate send controls per channel to maintain the correct stereo image in the delay return. In computer systems, things are usually a little easier, although it pays to check that it's all working as you hope. I was using an Apple Logic Pro system very recently, for example, and could find no straightforward way of panning the send from a mono track across the channels of a stereo delay effect — although whether this problem was my fault or the software's is anyone's guess!

Again, you could use only a single delay effect to pull your mix together, but I've found that setting up a couple of contrasting effects actually makes it easier to get results quickly: the first is a short 'slapback' delay, with 50-100ms delay time and zero feedback; and the second is a longer delay with some feedback and a delay time synchronised to the song's tempo. The short delay operates much like the short reverb I've already discussed, although you need to be careful feeding high levels of percussive sounds to it, as these can begin to sound as though they're flamming, interfering with the track's rhythmic pulse. Because the longer delay is tempo synchronised, it tucks itself into the mix in a very transparent way, creating the same kind of warmth and sustain as the longer of my two reverbs, but without adding much in the way of a sense of real space.

Bringing It All Together Many professional mix engineers have a selection of standard effects that they set up before they even start to mix, having learnt from experience which units and algorithms have reliably delivered the results they need on project after project. The four specific effects that I've described here are designed to be fairly all-purpose in this way, and can be used in tandem to tie together mixes in a variety of different styles. For example, if your recording is already fairly live-sounding and mostly needs 'gluing together', the shorter reverb and delay can come to the fore, whereas the longer variants can be faded up when more space or sustain are required to enliven something like a heavily-overdubbed pop or electronica record. Alternatively, the delays might take precedence where a track already has the necessary spatial character (or just needs to sound very upfront), but lacks a satisfying resonance and fullness. To show how these four effects can fit together, I've mixed that demo chorus section one more time using all four effects at once, to create the AllEffectsWet file, and you can use AllEffectsDry to get a perspective on how much difference they're making.

There remains one final very important point to make, though: the effects levels on most modern records don't stay static throughout, but actually adapt to suit changes in the arrangement and underscore the long-term ebb and flow of the mix. That means you shouldn't expect the reverb and delay balance in your choruses necessarily to translate directly onto a contrasting verse arrangement. To illustrate this, I've created three longer audio files of the demo song (the Automation files), taking in the first verse as well as the chorus. For AutomationInactive I've just kept the same effect settings I used in the chorus, and you can hear that the effect levels become a bit overbearing in the sparser arrangement. However, just fading down the levels of the two delays and the longer reverb during the verse using mixer automation easily sorts out this problem for the AutomationActive file, with the beneficial sideeffect that as the effects levels fade back up for the chorus section it makes the sound a bit more expansive and 'widescreen'. Again, compare these two audio files with the effectless AutomationDry for an idea of what the effects are adding overall.

Room For Improvement Even with audio files to demonstrate some of the factors involved, there's a limit to how far you can improve your mixing technique without giving it some practice, so if you've found the application of reverbs and delays to be a bit of a black art so far, try out the four-effect setup I've advocated above on a few of your own tracks. With a little experimentation, you'll find that your ears will begin to attune themselves to the more subtle characteristics of your mix, so that you can balance the effects levels for each track much more successfully.