REC-Fundamentals Ch 3 Introduction To Audio - Where Do The Mics Go

Chapter 3: Introduction to Audio—Where Do The Mics Go? Author: Eric FurgusonFocus: Placement of microphones in audio engineering.

Key Questions in Microphone Placement

• Central question: Where to put the microphone?

• Common convention: Place mics directly in front of instruments.

• Limitation: Relying exclusively on this can hinder creativity and break aesthetic norms of music genres.

Historical Context of Miking Techniques

• Pre-1960 recordings: Monophonic and limited to a few mics.

• Ensemble setups: Musicians spaced around a single microphone.

• Louder instruments positioned further away for balance.

• Continued use in recording styles: classical, jazz, bluegrass.

• Importance of knowing miking techniques for flexibility and creativity.

Close Miking Explained

• Definition: Microphone placed very close to the sound source.

• Benefits:

  • Increases isolation of the instrument's sound compared to ambient noise.

  • Allows for greater control over the sound balance between the direct sound and room reflections.

• Proximity Effect: Boosting of low frequencies when the microphone is very close to the source, enhancing the sound's impact.

The Near Field Effect

• Definition: Area around a sound source where the frequency response varies significantly.

• Importance of understanding near fields:

  • Mic positioning affects the tone and character of the recorded sound.

  • Example: Microphone placement on a guitar amplifier changes the tonal quality dramatically.

  • Application: Critical for achieving desired sound profiles in recordings.

The Role of Room and Distance Miking

• Expanding palette by miking further into the room:

  • More natural sound for individual instruments and ensemble blending.

  • Captures unique characteristics of the recording space.

• Historical relevance: Distance miking was the norm before the rock era.

• Case Studies: Songs like Led Zeppelin’s “Kashmir” utilize room sound effectively.

• Working with Limited Spaces: Unique acoustics of any room can produce original sounds.

Technical Considerations: Phase, Wavelength, and Comb Filtering

• Understanding how sound propagates is crucial:

  • Wavelength: Distance for a frequency to complete a cycle.

  • Frequency determines the wavelength, affecting sound recording and mixing.

• Comb Filtering: Results from phase cancellation between close and distant mics, leading to uneven frequency response.

• Mitigation strategies: Separate mics by sufficient distance and manage levels to reduce phase issues.

The Three-to-One Rule

• Definition: To minimize cancellation, mics should be separated by three times the distance from the nearest mic to the source.

• Example: If a mic is one foot from an instrument, room mic should be at least three feet away.

• Applicability: Mostly effective outside the near field where sound pressure behaves differently.

• Flexibility: Although a guideline, the three-to-one rule can be adjusted based on what is heard at the moment.

Polarity as a Solution

• Polarity switch: Inverts the audio signal, altering the phase relationship without mic repositioning.

• Distinction: Polarity vs. phase flipping:

  • Polarity: Refers to electrical signal direction; phase refers to time-based relationships.

Conclusion

• Key Takeaways:

  • Close miking is essential for modern recordings; understanding placement for punchiness and tonal variation is crucial.

  • Incorporating distance miking preserves the unique character of a recording space.

  • Blending near and far microphones provides the best of both worlds in sound engineering.

  • Continued study: Next chapter will focus on microphones themselves.

Summary: This chapter discusses the principles and techniques of microphone placement in audio engineering, emphasizing the importance of both close and distance miking. Understanding the historical context, technical considerations, and key rules like the three-to-one rule, enhances creativity and flexibility in capturing sound effectively.