Stereo recordings often have the kind of three-dimensionality you just can’t replicate using reverb or delay effects or the pan controls of your DAW software. Most stereo recordings are made using a pair of condenser microphones loaded with cardioid pickup patterns, though omni-directional and bidirectional microphones aren’t uncommon either. Usually, more high-end microphones can even toggle between all three patterns so you can pick one depending on the situation. If you want to know which microphone set-ups are best for recording in stereo, just read on!
How to Locate Where Sound is Coming From
To localise sounds, all of us subconsciously pay attention to three things: intensity, timing and timbre. By simulating one or more of these factors via the microphone configuration, you can easily create extremely realistic recordings. Say there’s someone playing guitar on your left. Here, the sound produced by the guitar will enter your left ear with more intensity than your right ear. Not only that, the sound will enter your left ear before it enters your right, resulting in a timing difference. Also, since your head’s basically obstructing them, your right ear will register fewer high frequencies, with a slightly duller sound as the result: a different timbre.
1. X/Y Configuration
An X/Y configuration consists of two cardioid microphones placed in such a way that the capsules meet as closely as possible at a 90-degree angle (see image below). Since the microphones each face a different direction, any sound the mike on the left records will sound increasingly softer as the sound comes from further to the left while more dull for the microphone on the right, and vice versa. Deploying two bidirectional microphones for an X/Y set-up is called a Blumlein configuration – named after British audio pioneer, Alan Blumlein. ‘His’ configuration is arguably better for recording spatial audio when compared to an X/Y set-up, simply because it also picks up the echoey sound of any reflections bouncing off the back wall.
The benefits of an X/Y set-up:
- Easy to set up.
- No chance of phase issues because any sound is captured by both microphones at the same time.
The drawbacks of an X/Y set-up:
- Mediocre stereo results because there’s no timing difference between the left and the right microphone.
- A potentially dull-sounding stereo centre because both microphones are set up off-centre at a 45-degree angle.
2. A/B Configuration
There are barely any rules that come into play when setting up an A/B configuration. In most cases, two omnidirectional or cardioid microphones are used and set up somewhere between 40cm and 60cm apart from each other. In practice, A/B set-ups are commonly used to record broad sound sources such as choirs, orchestras and drum kits. As long as there’s no gap that splits the stereo image, the microphones can be placed as far away from one another as needed.
The benefits of an A/B set-up:
- Clear audio registering across a broad range.
- Bigger-than-life sound thanks to huge timing differences.
The drawbacks of an A/B set-up:
- Recording in mono often results in phase issues due to huge timing differences.
3. ORTF Configuration
Originally conceived in the 1960s by France’s national TV agency, Office de Radiodiffusion Télévision Française, the ORTF configuration is built by placing two cardioid capsules 17cm apart, facing away from one another at a 110-degree angle. This literally mimics the way our ears are attached to our heads, which is why TV channels the world over use either the classic ORTF configuration or a version of their own.
The benefits of an ORTF configuration:
- Registers differences in intensity, timing and timbre for extremely realistic, detailed recordings.
- Easy to set up.
The drawbacks of an ORTF configuration:
- Due to timing differences, phase issues are likely to pop up when listening to any recordings in mono.
- The centre of the stereo image sounds a little dull because the microphones face away from the centre.
What About Mono?
So, while recording in stereo literally adds an extra dimension to your mixes, there are a few instruments that barely reap the benefits, including bass-heavy instruments like kick drums and bass guitars. After all, our ears struggle to localise any sound below 150 Hertz, not to mention that big directional differences across the low-end usually result in a more turbulent mix. In case you didn’t know, snare drums and vocals are commonly recorded in mono for maximum focus, so don’t write off recording in mono just yet!
» Cardioid Microphones: Small-Diaphragm / Large-Diaphragm
» Omnidirectional Microphone: Small-Diaphragm / Large-Diaphragm
» Bidirectional Microphones: Small-Diaphragm / Large-Diaphragm
» All Large-Diaphragm Condenser Microphones