Audio Recording Microphone Technique Basics

Orchestral Miking (spaced omnis - "T" stand) Orchestral Miking (Spaced Omnis - "T" Stand)
Adlib Steel OrchestraMost audio recording techniques can be classified as either "orchestral recording" (also referred to as "orchestral miking"), or "close miking".  These two techniques, as used for stereo recording, are discussed below.  Monaural recording is similar but with fewer microphones.  Surround sound adds a fair amount of complexity beyond what is discussed here.

There are advantages and disadvantages of both miking techniques.  I use orchestral recording for most of my steelband recordings, with the occasional addition of spot microphones.  Either technique, or a mix of both, may well produce the best results in a particular circumstance.

Achieving the best result depends on the acoustics of the recording venue, the size of the group being recorded and the presence or absence of vocalists or "electronic" instruments.  Additionally, the choice of technique to use may be influenced by external considerations, such as the equipment available and the budget; the amount of time available for setup, checkout and rehearsal; the presence or lack of sound reinforcement if the recording is a live concert; and a myriad of other factors. This article is an attempt to describe the two techniques, the differences between them, and the advantages and disadvantages of both.


 

What are Orchestral Recording and Close Miking?  What are the Differences?

Orchestral recording is just what the name implies: Making a recording (particularly of an orchestra, but the technique works for smaller aggregations) with a minimum of microphones.  They are placed to capture the audio (music and room acoustics) as it would be heard, under optimum conditions, from the best seat in the house.  Microphones are usually placed at some distance from the musicians, where there is a balanced acoustic mix of the musicians and the room acoustics.  The output of the microphones is typically recorded as a stereo track which, usually after some post-production processing, becomes the stereo master.

Close miking, in its purist form, involves placing microphones close to the musical instrument so as to pick up the sound of that instrument with a minimum of sound from the environment (room acoustics, noise, etc.) and from other instruments. Except in the case of soloists, this usually involves several microphones, often one or more per instrument, and either a mixing console or a multitrack recorder.  The multitrack recording is mixed down in post-production, usually to a stereo master.  The ultimate in close miking of an electronic instrument, like a keyboard, is not to use a microphone at all, but rather to use a "direct box," which connects the electrical signal generated by the instrument directly to an input of a recorder or mixer.

There are, in fact, an infinite number of combinations and variations of these techniques. You may add "spot mics" which are close miking instruments (or vocalists) in the orchestra/band that may not be picked up well by the orchestral mics, and (usually) record them on separate tracks to be mixed down in post-production.  Or, conversely, a set of stereo "ambiance" microphones may be added to a close-miked session, in order to capture the acoustics of the space and add some of the room character to the final mix.


 

 Orchestral Recording Basics


Under the proper conditions, an orchestral recording will most closely capture of the actual performance.  If the number of instruments is large, it is often the only practical way to capture the entire orchestra.  It is the technique least prone to operational errors, and can also be the simplest and quickest to set up and take down. If the acoustics of the performance space are good, the recording will capture the "sound" of the space.  If you are making a "live" recording with an audience, but without amplification, you will capture the ambiance and applause of the audience in the recording.

There are a number of different orchestral recording techniques, many dating from the earliest experimentation with stereo in the 1930s, some of more recent origin.  All are based on the performance characteristics of the particular microphones employed (especially their directional patterns), and the laws of acoustics and physics.  All of these techniques have particular advantages and disadvantages. Some may work better than others in a particular environment and for particular applications.  Be aware that all of these techniques involve using specific types of microphones at particular locations, often oriented in particular directions.  They all require that the microphones be located some distance from the musicians, in order to pick up a sound field that has been acoustically mixed. To some degree this is analogous to what your ears hear in the vicinity of the microphones.

It is worthwhile at this moment to describe the two methods your ears can distinguish the direction from which a sound comes:  Method one is by hearing a sound louder in one ear than the other.  The sound is coming from the side of your head where the ear is hearing a louder sound.  The greater the difference in volume, the further the sound is originating from the centerline of your head. 

Method two is hearing the sound in one ear slightly earlier or later that the other.  The sound is coming from the side of your head which hears it first.  The greater the time delay, the further the sound is originating from your centerline of your head.

Most people with normal or near normal hearing use both methods simultaneously to localize a sound.

It is worth noting that most close miked music mixed using a "pan pot" to directionalize an instrument left or right is depends completely on method one above.  The orchestral miking techniques described on the next two pages may use method one, method two, or both to directionalize what they are capturing.

As I will repeat several times, setting up two nondescript microphones at random locations directly in front of the musicians is not a proper orchestral recording technique and will, in all likelihood, result in a poor recording.


 

Some of the More Common Orchestral Recording Miking Techniques are:

More Stereo Mic Techniques on the Next Page


 

There are variations of the above techniques and any number of other stereo miking techniques, each of which has advantages and disadvantages.


 

Circumstances Under Which Orchestral Recording Will Present Difficulties and Quite Likely Will Fail to Give a Proper Capture

Most recordings of large orchestras or choruses are typically based on one of the orchestral recording techniques, often with some additional spot mics. 


 

Close Miking of a Sax (not optimum mic placement)Close Miking of a Sax (not optimum mic placement)Close Miking Basics


A multitracked close miked recording, if properly done, will give the recordist the most flexibility in editing and mixing the final recording.  With the proper equipment and trained musicians, the different instruments and vocals can be recorded at different times, and tracks can be replaced or re-recorded individually.  Unfortunately, recording tracks individually, without the entire band or orchestra present often  results in a loss of spontaneity and "vibes" in the performance. The recordings of individual instrument tracks will typically have more "presence", as less of the acoustics of the space is recorded in each track.

This also means that if the performance is being amplified for sound reinforcement or the acoustics of the space is undesirable, you have a much higher likelihood of capturing a good recording.  You get the ability to dynamically adjust the balance of the instruments/vocals by mixing the tracks in post production.  You may have the opportunity to share some of the same microphones for sound reinforcement and recording by using "mic splitters".  This is a technique typically used to get professional recordings or broadcasts of live pop music concerts.  Finally, you can "process" individual tracks in an infinite number of ways, applying frequency equalization, dynamics control, reverb or special effects to the individual tracks or selected groups of tracks before mixing the final recording.

It should be noted that if a recording is close-miked, it may be desirable to stereo close-mic some of the instruments, particularly the lead instrument(s) using one of the stereo miking techniques, and recording left and right tracks of that instrument.  In mixing, the two tracks can be panned slightly apart, giving an often desirable "width" to the instrument in the final mix.


 

There Are a Number of Issues in the Use of Close Miking and Multitrack Recording:

More potential recording issues on the Next Page


 

 Most recordings of "pop" music have been close miked and multitracked, since at least the mid 1960's.

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