Tips & Techniques
Technique : Effects / Processing
If you know what you’re doing, plug‑ins are best set by ear — but if you lack experience and take care to avoid rookie mistakes, dialling in an off‑the‑peg preset can still prove effective...
To really understand the finer points of a Digital Audio Workstation, you need to know how everything works in a traditional recording studio, including processors such as reverb, echo, compression and EQ that now exist as plug‑ins inside DAWs. Knowledge comes with time and experience, though, so ‘first contact’ with a DAW can be intimidating. To make life easier, manufacturers offer plug‑in presets that you can use in typical mixing situations. Preset sounds for plug‑in instruments can often be used with very little tweaking, but preset processor and effects settings are more problematic, as how well they work for you will depend on things like the level, frequency content and dynamic range of the signal, or the project tempo. So how can you ensure they do the job with the mimimum of intervention?
Crossing The Threshold
During our Studio SOS visits and Mix Rescue sessions, we often see DAW projects using a compressor preset that’s not compressing at all! The reason is obvious if you know about compressors, but for the rest of you, here’s the story. A compressor is part of a family of processors called ‘dynamics’ processors. These all respond differently according to the level of the signal being fed to the processor — and a preset designer can’t possibly know what level of signal you’re sending to the processor! Furthermore, the greater the difference between the quietest and loudest parts of the signal, the greater its dynamic range, so a singer with good mic technique will probably control their dynamic range to achieve a more consistent level than a less experienced singer, and thus require less compression to keep the level even in the mix. Again, the programmer of the compressor preset can’t know how much compression your singer needs.
Level‑dependent ‘dynamics’ processors include compressors, limiters, expanders, gates and de‑essers, and all have a threshold level that determines when processing kicks in. Compressors, limiters and de‑essers are designed to reduce the gain when the input signal exceeds the threshold level (they act only on the loud bits). Gates and expanders reduce the level of the signal when it falls below the threshold, usually to cut down the amount of noise or spill in between the wanted portions of the audio signal. In most cases, there will be a control called ‘threshold’, but in some compressor designs the threshold is built into a single ‘Compression Amount’ control.
Compressors: Typical compressors have lots of parameters that you can adjust, but if you were to pick, say, a ‘Male Vocal’ compressor preset, the ratio, attack and release times would probably be appropriate for vocals: all you really need to adjust is the threshold, so that the gain‑reduction meter shows the right amount of activity. (It’s still important to listen, to check you’re getting the desired result!). As you lower the threshold, more of the signal exceeds it, so more compression is applied. Gentle compression, to even out the level, typically shows a maximum gain reduction of about 5dB, but more assertive compression (as you might use on rock or urban vocals) can require gain reduction of around 10dB.
Compressors work by reducing the level of the loudest parts of the signal, so the compressor output may need to be ‘turned up’ to get the signal back up to its original peak level. To this end, most compressors include an output gain control, often called ‘make-up gain’. Some include an ‘automatic’ option for this, but different plug-ins seem to handle this differently, and it’s easy enough to set the make‑up gain yourself: adjust the level while keeping an eye on the track or plug-in’s level meter, so that you end up with a healthy signal level, while still leaving some headroom. Making something louder will make it sound more impressive, but that’s no different from raising the fader — so try to keep the compressed and uncompressed signals at the same subjective level.
Limiters: Rather than a variable threshold, plug‑in limiters often have their threshold fixed at 0dBFS, and there’s an input level control that can be used to boost the signal if you want to limit the signal peaks for the purpose of maximising loudness. Essentially, you only need to adjust the input level so that the limiter’s gain-reduction meter shows a dB or two of activity on the loudest peaks. If you want harder limiting, as you might on an individual drum, just turn the gain up a little more; let your ears decide when enough is enough.
Gates & Expanders: Like compressors, gate and expander presets will have their attack and release times tailored to specific applications, such as drums, vocals, guitar and so on. Again, though, you’ll need to adjust the threshold to get them to work correctly for your track. The simplest way to set them up is to set the track to loop around a section that contains both wanted signal and pauses; then, starting with the threshold at minimum, increase it until the noise in the pauses just disappears. Don’t set the threshold any higher than necessary to mute the noise, though, or you may start to hear the wanted signal being affected, especially where the signal has a wide dynamic range, or long, decaying tails. If you really want to minimise the chance of adverse side-effects when tweaking a gate, reduce the amount of attenuation (most gates, though not all, include a control for this) so that instead of muting the pauses completely, you simply reduce the noise to an acceptable level. Attenuating by between 10 and 20dB is often enough to keep the track sounding clean.
De‑essers: De-essers vary in design, but most have a variable sensitivity control, which essentially sets the threshold above which de‑essing takes place. A de‑esser monitors the frequency band most likely to contain sibilant ‘S’ and ‘T’ sounds, and then applies gain reduction to that part of the audio spectrum when loud sibilants are detected. Often there’s no gain‑reduction meter, so you simply have to adjust the sensitivity control by ear. What you’re after is a setting that reduces the ‘spitty’ character of those ‘S’ and ‘T’ sounds, but that doesn’t go so far as to make the vocal sound lispy.
Some specialist plug‑ins that reshape the envelope of a sound, or those that create swept‑filter effects, also rely on a threshold setting to adjust how they respond. The main exception is the SPL Transient Designer (and its many imitators), which intelligently varies its own threshold according to the input source, and works on material recorded at pretty much any level.
When it comes to EQ, the preset designers will once again have had to make assumptions about the source signal — so the presets won’t be a perfect match for your track. A Male Voice EQ preset, say, might not work in every case: for example, if there’s already plenty of 2.5kHz attitude in the voice, you’re not going to want to boost that band further! That said, the preset designer will at least have carefully chosen the frequencies that are likely to have the greatest impact on a typical male vocal — so usually the simplest way to tweak such a preset is to focus on changing the gain setting for each EQ band, without changing the frequency or Q. Gain or attenuation in these bands should make plenty of difference, even with reasonably small cut or boost settings.
Keep comparing the result with the clean (bypassed) sound, as it’s very easy to fool your ears into thinking louder and brighter means better! As a rule, use as little EQ as you can get away with to do the job. Using EQ effectively is a very necessary skill for any recording engineer, so also try to wean yourself off presets as soon as possible. There are lots of articles covering EQ on the SOS web site, for example at www.soundonsound.com/sos/dec08/articles/eq.htm.
After experimenting with the gain settings, the best way to ease yourself into parametric EQ is to experiment with varying the frequencies of the various bands to see what audible effect that produces. When you feel comfortable adjusting these two, move on to adjusting the Q or bandwidth, which controls the width of the cut or boost region.
There are three main adjustments you might want to make to a delay plug‑in: how much, how long and how many repeats. If you’re using a delay as an insert effect, the mix control determines how much of the delay you hear relative to the dry sound. If the delay is set up in a send/return loop, the mix control should be set to 100 percent wet. ‘Time’ determines the delay time (in milliseconds or in musical measures), and ‘feedback’ controls how much of the delayed signal is fed back to the input to produce further repeats. Many delays also include a tempo‑sync feature, which is only relevant if you recorded your song to the tempo grid, but it’s obviously helpful if you’re programming and experimenting with different tempos.
Many engineers record live bands without using the tempo grid, and though this makes editing a little harder, it can free the music from the ‘tyranny’ of the click track, which, in turn, can help the song ‘breathe’ through natural small tempo changes. In such cases, you’ll need to turn off tempo sync and set the delay time by ear.
Reverb comes in so many different flavours now, but back in the day, the plate reverb was about the only game in town, and I find that it still sounds right on almost anything. The main parameters that control the amount of reverb are the mix setting and the decay time. As with delay, set the mix to 100 percent wet if using in the send/return loop.
If you’re confused by the reverb options available, try starting your project with a vocal and a drum plate preset on two different effect sends, and then adjust each by varying only the reverb decay time to suit your track. You could set up more reverbs, but that’s a great place to start.
Reverb is such a taste‑driven thing that any judgement is purely subjective, but as a very general rule, there’s a trend on modern records to use less obvious reverb treatments than on those made in the ’70s and ’80s. A useful tip is to try mixing the different reverbs you’ve set up (as described above), because the chances are they’ll have different decay times — and that means that you can achieve useful ‘in between’ combinations by blending them.
Enhancers & Distortion
Typical harmonic enhancers synthesize new high‑frequency harmonics to brighten a sound that has little or no natural top end. If you choose a preset, the filter frequency that determines what part of the audio spectrum will be enhanced will already be set, so to make adjustments you need only vary the harmonics ‘amount’ control.
Distortion plug‑ins are popular for applications ranging from adding a little warmth to a voice or synth to making an electric guitar sound like a blender full of barnacles! Chances are that your DAW will offer you several different types, with presets based on each — so try them all, to get an idea of their tonal differences, and then adjust the ‘drive’ setting to add more or less distortion. Many types of distortion are also dependent on signal level, so the lower your recording level, the higher the drive setting is likely to need to be to get the same result.
Modulation effects include chorus, flanging, tremolo, vibrato, rotary‑speaker effects, and so on. While rotary‑speaker plug‑ins tend to have fast, slow and stop settings, the others are often more adjustable, and the general rule is that if you speed up the effect, you should also reduce the depth setting — especially when dealing with chorus and flanging. If you simply turn up the speed of a chorus or flanger without also reducing the depth, you’ll tend to end up with a nausea‑inducing warble — but then I suppose that might be what you’re after, so feel free to experiment! Some tremolo and panner plug‑ins have a tempo‑sync option, which is worth trying if it isn’t already engaged when you open the preset.
Some DAWs allow you to save all the plug‑ins used in a channel strip as a kind of ‘combo’, or ‘channel preset’. These can be called up for use on another channel, or in another project, and can save you lots of time when working with similar material. Although they can be a great starting point in a new project, do bear in mind that the key parameters for each plug-in, such as a compressor’s threshold, will probably require tweaking for every track to which the preset is applied.
The Future Of Presets?
Though not directly related to this article, some plug‑ins, such as the Waves Producer series and the Izotope Nectar Vocal Suite, make life easy by hiding away the controls that you’re not likely to need to adjust. That way, you only have to deal with the important controls — which is an approach that’s a bit like the preset editing advice given here. I find this a good halfway house between tweaking everything and simply calling up presets, and because of the work that has gone into designing them, the results can be extremely good. Maybe we’re moving towards an era where the software treats us more like musicians and producers, and less like engineers?