Extreme close miking can be an aesthetic choice or an uncomfortable necessity. Either way, it’s important to know how to get it right.
Ever since multitrack recording was invented, it’s been common to mic every instrument individually. That’s true both for live ensemble recordings and for more ‘produced’ records built up through layers of overdubbing. Sometimes the individual mics are used to augment the capture from more distant mic arrays, as with spot mics on orchestral instruments, or close mics on snare and toms in a drum kit. Often, though, it’s the individual mics that provide the main or the only capture of each source.
When we record like this, one of the main concerns is separation. If there is more than one instrument playing in a single space, we want to be able to capture the sound of each instrument to a separate track, minimising bleed or crosstalk between them. Depending on the circumstances, we may also want to capture the sound of the instrument without a strong acoustic imprint from its environment.
There are several factors in play here, but usually the most significant one is distance. The nearer the mic is to the instrument, the higher the ratio of wanted sound from that instrument to unwanted sound from other sources and room reflections. In a close position, the mic also encounters a greater absolute sound pressure level from the instrument. This can be an important consideration with quiet acoustic sources, because it helps to deliver a higher signal‑to‑noise ratio.
The importance of keeping the distances from source to mic short is well known to live sound engineers. In a typical stage environment, not only is there no baffling or other acoustic separation to block spill from other instruments, but the sound from our mics is being amplified and played out through stage monitors and front‑of‑house speakers. Moving the mics close to the sources is therefore essential, not only to achieve separation but also to avoid feedback.
Experienced studio engineers, by contrast, are sometimes suspicious of very close miking. In fact, you could say that what we look for in a studio live room is an acoustic environment that makes close miking unnecessary, or at least optional. The beauty of a space like Abbey Road Studio 2 is that you can pull the mics further back from the source without unpleasant coloration, excessive reverberation or problematic leakage creeping in. We’re often told that we shouldn’t be afraid of spill: even that it can supply the ‘glue’ that helps a recording come together. So are there any circumstances in which very close miking might be a positive choice in a studio environment? And what considerations do we need to bear in mind when making this choice? This is a topic that Eddy Brixen has been researching for DPA Microphones, and in this article, I’ll be sharing some of his insights.
It’s no surprise that musicians often prefer a nearfield miking approach, because it is more likely to produce a sound that they are familiar with.
First of all, let’s quickly introduce some theoretical concepts. What we’re talking about here is nearfield miking: positioning the microphone so close to the source that its capture is dominated by sound radiating immediately from the instrument. We are defining the nearfield as the zone around an instrument where the ratio of direct sound to reflected sound from walls, floor and ceiling is high enough that the latter is basically negligible.
It’s important to note that the extent and location of this nearfield zone varies a lot. In some cases, the shape of the instrument and the properties of the environment might make nearfield miking altogether impractical. I’ve had the good fortune to record a couple of sessions in the Chapterhouse at Wells Cathedral, which is a large octagonal space faced entirely with stone, and capturing a ‘dry’ sound in there would be impossible. By contrast, an anechoic chamber extends the ‘nearfield’ throughout the entire space.
It’s also vital to bear in mind the differences between different musical instruments. In the abstract, we can think of three types of ‘ideal’ sound source: a point source, a line source and a plane source. An ideal point source emits sound equally in all three dimensions. A line source radiates in two dimensions only — for example, it might emit sound horizontally but not upwards or downwards. An ideal plane source would beam sound only in one dimension.
Musical instruments typically display a complex mixture of all three behaviours. Different parts of the instrument can radiate sound in different patterns, which can vary with frequency. In the distant field, all these elements merge together with reflections from the environment to create the sound of the instrument as it would be heard by the audience, at least in an unamplified performance. In the nearfield, there is a tendency for instruments or their component parts to approximate plane sources, and these different elements are less integrated. The upshot of this is that placing the mic very close to the source introduces a number of interesting considerations.