Quick Tip: Refining the Details in Your Audio Production
Have you ever wondered about what a mastering engineer thinks of the mixes he's given? The details he hears that the producer missed? The things he wished were fixed during tracking and production? Well, today you find out.
This quick tip is written by Barry Gardner, sole mastering engineer at SafeandSound Mastering.
These days most musicians and producers have some kind of music composition software at home, running on a PC or Apple computer. There is an obvious learning curve for people who are sequencing their music using a digital audio work station. High quality recording and mixing is a challenge in itself.
For people who are already successfully making their own musical productions I wanted to cover the topic of sonic details. We all know the value of high quality recordings and good mix downs. These skills both show your music off at it's best and convey it's message unhindered to the listener.
As a mastering engineer I often hear small details in the music which go missed and unnoticed by the producer and/or engineer during mixing. Often it is a matter of focus, when listening to the overall instrumental tone and balance small details can be easily missed. This is understandable as the engineer is trying to take in the bigger picture and not each little extraneous noise.
Vocal pops are best stopped completely at the recording stage. I recommend using a nylon mesh (not metal) pop shield 4-5 inches in front of the microphone.
Pops can be tricky to edit out unless you have a very good audio editing application, so best to avoid them in the first place. If however you have recorded some pops (and it does sometimes happen even if you have a pop filter in place) the two main means of removal will be editing them out, adding small fades or momentarily automating a high pass filter on the plosive.
Clicks in Your Stereo Mix Bounce
Clicks can be caused for many different reasons. Sometimes a click can be generated when an edit has been made in a piece of audio.
Many sequencers have a setting which automatically creates a small cross fade when you edit the audio, however some do not. If you create an edit in the middle of a waveform peak you can produce a click when joined with the next piece of audio.
Ideally you need to edit at what is known as the "zero crossing point" in a waveform. The red cursor is positioned at the zero crossing point of a waveform in this image:
When you zoom into your waveform, look closely and try and edit when the waveform shape crosses the centre line and not when there is a peak or trough in the waveform. When editing in this manner they should not produce a click.
When you bounce your audio mix down sometimes you can get a CPU overload and this will result in a small click or glitch in the file. The best plan is to ensure you have disabled any plugins that you do not need and re-bounce the mix again, double checking on headphones. If you still have a problem with the resultant file considering using the track freeze option that many DAW's have.
Another common source of clicks is a vocal performance, sometimes the mouth can make small click-like sounds (which are often enhanced by use of high frequency EQ boosts). This is known an 'lipsmack'. These can sound unpleasant and are best edited out of the performance.
Bad edits are simply edits that lose musical timing. They are easily heard when focusing on the rhythm of any piece of music and can obviously occur on any instrument.
These are very obvious to hear but are often missed. The musician or producer is listening globally to their production and is highly involved in it.
Sometimes you need to step back and listen with a fresh approach to only the timing aspects of the music and not the mix, melody or vocal tuning. Then you can tune into any problem edits that miss a beat.
Hiss and Hum (Noise)
Hiss has become less common since digital audio workstations have been prevalent and tape (the biggest hiss culprit) has been largely abandoned. However do check track recordings that needed a lot of gain from your mic preamps, i.e. quiet sources with dynamic mics and also guitar amplifiers.
Hiss and hum is best avoided at source, as removal using noise reduction can have an impact on fidelity and tone during mixing. I recommend ensuring your signal to noise ratio is high through the recording chain and make sure your gain structure is optimized before making any recordings.
Hiss is often heard when an instrument decays and is most easily audible on a pair of good quality headphones.
Bounce/Export Pre and Post Roll
Sometimes tracks are bounced and the very first instrument in the track is cut off accidentally and at the other end of the track sometimes reverb tails and/or instrumental decay can be cut off prematurely.
I suggest placing your bounce/export timeline locators three seconds before the first piece of audio and three seconds after to avoid any audio being cut off accidentally.
This image demonstrates a good pre roll for bouncing your mix down:
DI Guitar Thump
When you DI a guitar there is often some very low frequency thumping that accompanies the picking and tapping of strings. This happens especially when using an acoustic guitar pick up as the hollow body resonates and amplifies the thumps.
If you use a spectrum analyzer you will see lots of energy down at the 20-50 Hz area of the spectrum and this is best filtered out to a degree which retains accent of the picking/tapping but does not cause excess thump on a full range system with deep bass response.
So all it takes is a little extra work to resolve some common extraneous noises, put your headphones on, listen deep into your mix and clean up your tracks before they leave your studio.
Monitoring is Important
The problems outlined above highlight why high quality studio monitors are very important when recording and mixing music. These issues are often missed on low quality loudspeakers. Lower quality drivers will cloud over the sonic information and small details in your mix will not be presented to your ears and they will go unnoticed.
I recommend that a very high quality pair of headphones be used to be able to hear these types of problem more easily after a mix has been performed. These can block out external sounds and help you focus on hearing the details.
You need to listen to the technical presentation of the music rather than the emotional and performance aspect of the music.
A little tip I can offer is to add a high shelf boosting about 6 dB from 5 kHz across you whole mix. This accentuates the glitches and makes them even easier to hear in headphones as it 'brightens' up the sound. Do be aware that could enhance hiss and make sure you remember to remove it before you bounce your file.