Mic It!

Microphones, Microphone Techniques, and Their Impact on the Final Mix

Ian Corbett

• Publisher: Routledge
• Year: 2020
• Print ISBN: 9780367470364
• eBook ISBN: 9781000289213
• Edition: 2
• Topic: Media & Performing Arts
• Subtopic: Acoustical Engineering

Capture great sound in the first place and spend less time "fixing it in the mix" with Ian Corbett's Mic It! With this updated and expanded second edition, you'll quickly understand essential audio concepts as they relate to microphones and mic techniques and learn how to apply them to your recording situation. Mic It! gives you the background to explore, discover, and design your own solutions, enabling you to record great source tracks that can be developed into anything from ultra-clean mixes to massive, organic soundscapes.

Beginning with essential audio theory and a discussion of the desirable characteristics of "good sound", Mic It! covers microphones, mono and stereo mic techniques, the effect of the recording space or room, and large classical and jazz ensemble recording. This second edition also features new chapters on immersive audio, immersive recording concepts, drum tuning, and recording techniques for audio for video. Mic It! provides in-depth information on how different mic techniques can be used, modified, and fine-tuned to capture not only the best sound, but the best sound for the mix, as well as how to approach and set up the recording session, prepare for mixing, and avoid common recording and mixing mistakes.

• Train your ears with practical audio examples on the companion website.

• Develop and test your knowledge as you learn, with concise, applicable exercises and examples that cover the concepts presented.

• Record the best sound possible in any situation with Mic It!

Corbett's expert advice ranges from vital knowledge no novice should be without, to advanced techniques that more experienced engineers can explore to benefit and vary the sound of their recordings. Whether you only ever buy one microphone, are equipping a studio on a budget, or have a vast selection of great mics to use, with Mic It! you'll learn how to make the most of the tools you have.

1 Audio Basics

In This Chapter:

1. 1.1 It’s Not Always About the Gear!
2. 1.2 What is Sound?
3. 1.3 The Decibel (dB)
4. 1.4 Power Relationships
5. 1.5 Decibel Scales
6. 1.6 Dynamic Range
7. 1.7 Signal-to-Noise Ratio
8. 1.8 Frequency vs Pitch
9. 1.9 Frequency Response
10. 1.10 Waveforms, Fundamentals, and Harmonics
11. 1.11 Wavelength, Velocity, Phase
12. 1.12 Amplitude Summation and Comb Filtering
13. 1.13 Human Hearing
14. 1.14 Signal Flow and Audio Level Standards
15. 1.15 Gain Structure and Recording Levels
16. 1.16 Analog Audio Connectors
17. 1.17 Digital Audio Connectors
18. 1.18 Digital Audio Basics

An engineer who knows how to use a mic is more important than the mic.

–Wes Maebe, Engineer/Producer: Sonic Cuisine, RAK Studios, London, UK

The best microphone I’ve used in my life was the one that was up when the artist did something great.

–Joel Hamilton, Producer, Engineer, Co-Owner: Studio G Brooklyn, New York, USA

1.1 It’s Not Always About the Gear!

Gear, gear, gear! We all want to get our hands on new toys, plug that gear in and make sound… There’s nothing wrong with that! But even the best audio equipment available won’t produce great sound unless you understand how to use it properly. Lower quality equipment used well, will always sound better than great quality equipment used poorly.

Sound is our artistic medium. As sound engineers, we create sonic artwork from it. The more we understand it, the more we can predict its behavior, and more easily produce better recordings. You’ll be much better prepared to get the most from the concepts discussed later in this book, and to produce great recordings, if you have a good understanding of fundamental audio theory and studio basics. Don’t skip ahead! There might be something in this chapter that will change the way you think about sound, use your equipment, or hear what you’re listening to – improving the audio you record and mix.

1.2 What is Sound?

Examples of objects that produce sound include the strings on a guitar or violin, the reed in a wind instrument mouthpiece, a trumpet player’s lips, the head on a drum, and a loudspeaker cone or headphone driver. All of these sources have one thing in common – they vibrate, creating variations in air pressure, which become sound waves. Sound does also travel through other mediums, such as water and solid objects – but seeing as air is the medium that usually surrounds us, we’ll concentrate on that!

Figure 1.1 shows a simplified, illustrative picture of a vibrating guitar string. The string is anchored at both ends, and stretched so it is taut. When it is plucked, bowed, or struck, it is set in motion and vibrates. During this motion it moves from its point of rest (the position it naturally returns to when not in motion), labeled A, and out to an extreme, labeled B. As it approaches B, the tension in the string increases until it is not able to move any further, and it rebounds back in the opposite direction, through A to the opposite extreme, C. Tension builds as it moves towards C, and causes the string to reverse its direction again, so it moves back through A towards B. A little energy is lost with each consecutive change in direction, so the string gradually moves less and less (getting quieter and quieter) until it is stationary and silent back at its point of rest, A.

Figure 1.1 The motion of a vibrating string, and a resulting sound wave.

As the string moves from A to B, it squashes the air molecules to the left of the string closer together. This increases the air pressure in that spot, causing a compression. This compression then travels outwards from this source at the speed of sound. The air molecules themselves do not move far – the compressed group of molecules bump into the adjacent molecules, which bump into the next set, passing the compression on.

As the compression travels outwards, the string moves back through A, where normal atmospheric air pressure is restored. During the subsequent motion from A to C, the air molecules to the left of the string are drawn further apart, to fill the space where the string used to be. This causes a decrease in air pressure to the left of the string, called a rarefaction. This rarefaction travels outwards, following the previous compression. As the string returns to A, normal air pressure is once again restored behind the rarefaction. This continuing motion propagates the alternating compressions and rarefactions of sound waves behind each other. Greater motion and displacements from the point of rest create greater variations in air pressure and louder sounds.

The Speed of Sound

The speed of sound is commonly quoted as being around 344 meters (1130 ft) per second – for dry air, at 20°C (68°F), at sea level. As general principles, the speed of sound:

• Increases as air temperature rises, and decreases as air temperature falls.
• Decreases slightly as altitude increases (though this has more to do with the altitude-associated temperature decrease than the change in air pressure).
• Increases a little as humidity rises.

Figure 1.1 also shows two ways of graphically representing these sound waves. The first is a series of blobs representing the relative spacing of the air molecules – the air pressure. The second is a time/amplitude graph. This graph may look familiar. It is the shape of a sine wave – a pure tone made up of one single frequency. An actual vibrating string produces a much more complex harmonic waveform than a sine wave, as shown in Figure 1.2.

Figure 1.2 The waveform produced by an actual guitar string, showing the overall motion of the string produced by the interaction of all the frequencies present.

Time/amplitude graphs are based on measurements taken at a single point in space, over a duration of time. This is similar in principle to what a microphone does – a mic is positioned at a single point in space and takes measurements of air pressure over time, capturing frequency and amplitude information.

1.3 The Decibel (dB)

The amplitude, or “amount of” a sound’s energy is measured in decibels. Meters, faders, and the scales on many equipment knobs are in dBs, so it is vitally important to understand the concept in order to use audio equipment correctly. The dB is a unit of convenience. By itself it only implies that we have reduced a much larger range of numbers into a smaller, more manageable range of numbers in the form of a dB scale of some sort.

For example, a more familiar unit might be the watt – used for measuring power. Power is a measure of the energy consumption or energy transfer of...

Table of contents

• Cover
• Half-Title
• Title
• Copyright
• Contents
• About the Author
• Acknowledgments
• 1 Audio Basics
• 2 “Good Sound”
• 3 About Microphones, Part 1…
• 4 About Microphones, Part 2…
• 5 EQ Basics
• 6 Stereo Imaging
• 7 Stereo Microphone Arrays
• 8 Immersive Audio
• 9 The Effect of Microphone Position
• 10 The Recording Room
• 11 Recording Vocals
• 12 Drum Miking
• 13 Drum Tuning
• 14 Guitars, Basses, and Keyboards
• 15 Strings, Winds, Brass, and Percussion
• 16 Setting Up the Studio
• 17 Miking Large Ensembles
• 18 Putting It All Together
• 19 Audio for Video
• 20 Tips From the Professionals…
• Index