Analogue Warmth
Vintage desks and outboard are celebrated for their ability to ‘glue’ a mix and impart ‘warmth’. But what do these vague terms really mean, and how can we recreate the effect?
Do you need to scour eBay for relics that imbue your work with their much-extolled ‘warmth’ and ‘glue’? We translate the lingo – and offer some new era solutions
A good mix is so much more than the sum of its parts. And yet sometimes, no matter
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our sounds, we just can’t get them to stick together in a way that is musically pleasing. ‘Mix glue’ is a term you’ll hear frequently and it’s self-explanatory; a ‘glued’ mix is one which holds together beautifully, where every part works in perfect harmony with every other.
Exactly how this is achieved is not immediately obvious, so through the next few pages, we’re going to explore some of the ways in which we can bring that much-coveted glue to our mixes. In particular, we’re going to focus on an understanding of why dynamics and space (compression and reverb) should be particular considerations. But we’re also going to go further to explore another commonly used phrase
– mix warmth – and discover how we can bring this to our mixes too. For all of its practical limitations, tape-based recording rarely failed to add its own sonic personality and character to tracks, whereas we have to work a little harder to bring these sought-after qualities to our digital mixes. So in the spirit of mix enhancement and hot on the heels of mix warmth, let’s go exploring.
What is mix glue?
For most people interested in sound, the discovery that music is recorded
one instrument at a time is revelatory. If you’re reading this, you’ll probably have discovered this a long time ago and so the impact of realising that the drums and the guitars and the bass and the vocals and the synths are all tracked one part at a time may have diluted somewhat. But in case your memory is hazy, this is a mind-expanding moment for most young producers/ composers/artists and particularly those who are multi-instrumentalists, who suddenly realise it might be possible to be ‘the whole band’, not just one instrumentalist within it.
Of course, the reason that this discovery is made at all is because, in most everyday circumstances where sound is encountered, it isn’t performed one part at a time. Go and see a symphony orchestra and you won’t find the first part of the concert is ‘just the strings’ and that the second is ‘just the brass’; everyone onstage plays together. Similarly, go and see your favourite band live and it’s the sound and the chemistry of those musicians joining forces which is so electric. So why don’t we do this in the studio? Why do we split everyone up and record one part at a time?
Well, for the simple reason that it provides us with choice later on in the process. If you record the vocals at the same time as the piano, for instance, if you suddenly want to change the tone or the reverb or the dynamics of the vocal, those decisions will have implications for the piano captured simultaneously. Separate them and you have all the flexibility you need. This is even more true if you’ve recorded in a ‘dry’, acoustically-controlled environment, where your choices won’t be compromised by a sub-optimal recording space when it comes to the mix stage.
So there you are with beautifully captured audio, one track at a time, with – in all probability – a slight sterility pervading your project. It’s no surprise to discover that your mix lacks cohesion, togetherness or what we often refer to as ‘glue’. What is the stuff that sticks a mix together and makes it sound ‘as one’, even when it’s been constructed from layered individual performances? What are the parameters at our disposal which allow us to give the impression that each performance was carried out to be part of a ‘whole’, rather than to stick out like a sore thumb on its own?
Through the following walkthroughs and examples, we’re going to find out that there are a number of ways that you can glue your mix together, to bring a cohesion which will significantly improve the quality of the tracks you make. Once upon a time, you understandably assumed that the records you heard were made by a group of musicians in the same room at the same time. Why? Because of the techniques we’re about to explore.
What is it that sounds so sonically rounded about listening to a drum kit? The volume of a live drummer is certainly an impressive thing. But there’s something ‘complete’ about the sonics of hearing the assorted pieces of a drum kit which isn’t quite true of a solo lead guitar or bass, either of which could be just as loud. Interestingly, the moment a drummer limits herself to only playing the kick, or a kick in combination with a hi-hat pattern, a temporary ‘incompleteness’ occurs, which is only addressed when she builds back up to a full pattern once more. The same thing is true of going to hear an orchestra – the delicate start on horns or strings giving way to everyone playing together can be musically transformative. In both instances, the ‘sonic completeness’ is offered by the combination and number of harmonics we’re exposed to as we listen.
The science bit
Take the drum kit as an example; the kick drum provides low and low mid-range frequencies, the snare offers solid mid-range and the hi-hat and cymbals provide sizzling treble. Whilst it’s possible to overload a mix in a particular frequency area so that it lacks balance and focus, it’s also true that it’s not quite possible for a mix to feel sufficiently glued together without each of these frequency bands working well in combination. To understand this, we need to break down how sound works, so we can use its science to help when it comes to issues surrounding ‘mix glue’.
Whenever an acoustic sound plays, alongside the ‘triggered’ note’s core frequency (called the ‘fundamental’), a series of harmonics or overtones sound as well. These are related, mathematically, to the fundamental frequency, so almost always the loudest harmonic you’ll hear is the first one, which is a doubling of the fundamental frequency. Let’s suppose your fundamental frequency is at 100Hz – its first harmonic will be at 200Hz, which is an octave above the fundamental. Ever wondered why the notes in a musical scale cycle back round to the same letters? It’s because all of the C notes are related to each other, as are all of the Ds and all of the Es etc. Every time we jump an octave, the frequency doubles. So, in other words, you’ll hear an octave at the first harmonic (200Hz in our example), at 400Hz (the following octave), at 800Hz (the next one), 1.6kHz and so on. However, 300Hz is also a multiplication of our fundamental frequency, but it clearly can’t be at an octave – it must be somewhere between the first harmonic (200Hz) and the third (400Hz). Indeed it is – exactly halfway between –which makes it an octave and six semitones above the fundamental frequency.
These harmonics are the very essence of sound. In fact, the combinations of harmonics in every sound entirely define their character. If you were able to take any two acoustic sounds playing the same pitch, leaving only the fundamental and strip them completely of all of their harmonics, they’d sound exactly the same. What makes a violin different from a trumpet or one synth oscillator waveform different from another is the arrangement of harmonics on top of the fundamental. This matters hugely when you’re searching for warmth and glue in your mixes.
Adding harmonics
Warmth is often a term attributed to analogue equipment and, in particular, to the golden age of tape recording where it was possible to ‘saturate’ a tape with volume so that it started to gently and musically ‘distort’. Guess what happens, in mathematical terms, when tape does that? That’s right, harmonics are added, which have the potential to enrich a mix considerably. And if those harmonics are added carefully and from every sound in the mix, perhaps because you’re working with a tape saturation plugin at the output stage, ‘glue’ is provided since every sound is working together to generate those new harmonics.