In Summary
Despite some sonic advantages and the creative potential that layered recordings can bring, the magic of recording bands playing live in the studio can be hard to beat. Here we share our tips for keeping wandering sounds under control.
Going Deeper
Engineers working with bands who play together live have a number of options for getting a sound that properly translates the sound, feel, and emotion of the music. For many productions this means balancing fidelity with excitement, as the two aren’t always the same thing!
This isn’t to say that plenty of excellent-sounding records haven’t been made by building up all the parts as overdubs, or perhaps by replacing a master take piece-by-piece. This provides a lot of control and potential for editing where the music could do with a little help, or perhaps where the priority is a polished sound. Other productions might see a live master take augmented with overdubs for vocals, and other topline elements that require an extra focus on attention to detail. For those who seek the authenticity of a live rendering, with some seductive sheen for key elements, this is a popular approach.
For others, the only way to bottle the energy, excitement, and chemistry that can happen between people playing music together is, (you guessed it) to record them together as well. Anyone who has seen the smiles on everyones’ faces on that first playback might agree that this beats hours, days, or weeks in the control room chasing perfection that will never appear.
For any ensemble recording, especially when everyone is plugged in, it’s inevitable that microphones will hear some or a lot of everything as well as their intended target. These unwanted sounds are what make up spill, or bleed. Although keeping this to a minimum is the fundamental aim (too little is less of a problem than too much), what is captured is one of the things that makes live recordings sound so vital. With a little listening and some simple techniques, spill needn’t be a problem. Doing this can of course be used for hybrid productions that combine live atmosphere with overdubbed perfection. Here are our techniques to ensure that every last sound serves the song.
Session Layout
Performers
In acoustic ensembles, it’s a good idea to allow performers to put themselves where they want to be, although steering people towards a part of the room with fewer hard surfaces will help (this will often be where everyone has dumped their stuff!). Many unplugged bands will rely on being near to each other to get their internal balance and to hear themselves without headphones (more on which later). Some will have spent years playing in a familiar layout. It’s best not to upset this in aid of reducing spill, and a relaxed recording with spill is better than its opposite.
In a loud, plugged up situation, it might be temping to try and increase the distance in between performers to reduce spill. This can work in dead spaces, but the available room will sometimes dictate where things land, and often there won’t actually be that much wriggle room anyway. In more reverberant spaces, increasing distance will have less of an effect on reducing spill. One argument is that the real enemy is late spill. By living with slightly earlier spill from the session’s layout, the effects of differing delayed sounds may be less of a problem.
Gobos And Baffles
Moveable screens need to have large dimensions and hefty construction to be of any real use. The first thing to bear in mind is that screens exist to cast sound shadows, with bigger gobos able to be effective down to frequencies and wavelengths related to the size of screen. That also means having enough size and mass to absorb low frequency energy and enough size to stop low sounds wrapping around them.
Trying to ‘box in’ things like drum kits and guitar amps can improve the situation, but may only help with mid and higher frequencies. Shielding quieter things can be more effective. This is analogous to casting shadows with a sun visor to reduce glare. Luckily some of the most fragile sounds take High Pass Filters well enough to negate any gatecrashing low frequency content.
There are a number of baffles that are designed to be used behind mics to stop energy going into the room or to stop incoming spill. These can sometimes improve things, but cardioid mics need room to breathe at the back. I’ve used some small on-mic solutions that make things sound much worse than the problem they’re are trying to solve. If there isn’t time to find out one way or the other, consider going without.
Managing Levels
Virtually every act wants to sound their best, and most of these will put their trust in the engineer when suggestions are made. Things like loud guitar amps pointing at pianos, or that snare drum that lights up the vocal channel can all be improved with collaborative effort. Getting into a race to the bottom for levels will help things although levels will creep up more the further down you go! It’s perhaps best to remember that this is all about atmosphere over technical prowess…
Large guitar stacks are surprisingly directional through the mids and up, and can be steered away from other things. Piano lids can make good supports for a blanket or duvet ‘tent’. Anything with a level control can be, well, controlled. With low end clutter as the big enemy, running bass amps as low as possible and taking a DI are essential. On a related note, singers with too much foldback will often move back or otherwise make themselves quieter; giving them exactly what they want will pay dividends in keeping them the loudest thing in their own mic.
Headphones & Monitoring
While acoustic acts will often perform at their best without headphones, loud bands will almost always need some kind of monitoring. This can really help the spill situation because anyone with as much of themselves as they like in their cans is less likely to turn up or hit harder in their absence. Any headphone bleed will usually be masked in loud situations.
Loudspeaker wedge monitoring for stage can be used for those who really don’t want to use headphones, although this is less common. Again, keeping the level as low as possible is key, and a certain amount of technique with mic polar pattern and the monitoring itself will help such as using an old live trick with two mono monitors.
Microphone Polar Patterns
Much can be achieved using the ever popular cardioid pattern to reject spill. Putting any spill-producing culprit to the rear of the mic can help a lot, or even just a simple adjustment of angle can buy a few dBs’ worth of improvement.
It’s been said that omni mics’ inherently better off axis performance could keep them in the picture as an option for live recording with ‘good’ spill, although it’s probably true to say that miking an exposed acoustic guitar with one might be asking for trouble. Certainly the omni’s sonic advantages might be limited to loud things such as drums when reducing spill is a concern.
Despite their deep side nulls, figure of eight patterns should return the same direct-to-reverb ratio as a cardioid pattern (on paper at least). This can make them a worthy choice for managing spill, not only because of their highly steerable ‘deaf’ spots, but also because any spill is not subject to some of the colouration that cardioids’ spill can have. A classic deployment for figure of eights is a singing guitarist or two. A pair of musicians can be placed along an arc for maximum relief from crosstalk.
Noise Cancellation
At The Mic
Excess spill or noise can be reduced at the mic without the aid of any physical barrier. A second identical ‘B’ mic next to the A mic in question can be rigged around 20cm (8 inches) away. Omnis work best for this. The A mic contains the wanted signal such as the vocal, plus the diffuse spill from the room. The B mic contains almost exactly the same spill but far less of the wanted signal. When the B mic is subtracted from the A mic using polarity inversion, this cancels much of the noise but keeps much of the wanted signal.
In case you’re wondering, this is how many mobile devices do it as well. The same effect can be achieved singing very close to a figure of eight mic, were diffuse spill cancels itself out from each side leaving big pressure differences in tact (that’s the vocal to you and me). Specialist ‘lip’ mics exist for this very purpose for sports commentary in noisy environments.
In The Box
There are a number of noise reduction tools out there, either in audio plugin or standalone form. Although these can have a distinctly post production audience for dialogue editors, they will still work in musical settings. The growing number of stem separation tools may also have something to offer when it comes to sucking the spill out of a recording.
Spill For Good?
We talk a lot on the blog about making things sound the very best they can. Paradoxically, what makes the best songs embed themselves in the listener’s mind doesn’t always involve sonic or even musical perfection. After all, can anyone really define that anyway? Band recordings that stick in the mind reflect what it’s like to be human in every way, and this extends to all those glorious imperfections and the energy that happens between people. Getting everyone in the same place at the same time is the perfect way to capture this, despite the challenges that come with it.
The live aesthetic and its inherent spill are two of those elements in record-making that cannot be faked. With a little pragmatism it can actually add value and a visceral quality that will stay with the listener. When it comes to authenticity and excitement, far from being the enemy it could be the engineer’s best friend.
A Word About This Article
As the Experts team considered how we could better help the community we thought that some of you are time poor and don’t have the time to read a long article or a watch a long video. In 2023 we are going to be trying out articles that have the fast takeaway right at the start and then an opportunity to go deeper if you wish. Let us know if you like this idea in the comments.
Vocalist photo by Andrea Piacquadio on Pexels