Audio Pro 2 Feb 20

Introduction to Microphones

• Microphones have unique designs that enable them to convert sound into electrical signals. They are essential in audio recording and reinforcement.

Types of Microphones

1. Dynamic Microphones

• Functionality: They utilize a magnet and coils mechanism to convert sound pressure into electromagnetic charge through the movement of coils in response to sound waves.

• Limitations: Inherent limitations are observed in high-frequency responses. The moving coils are heavy, leading to less sensitivity to high frequencies.

• Advantages: Dynamic microphones do not require external power in most cases, making them user-friendly.

• Common Models: Includes Shure SM57, SM58, and Sennheiser models, among others.

2. Ribbon Microphones

• Design: These microphones use a thin metal ribbon instead of coils. The ribbon's movement creates sound pressure variations.

• Characteristics: They are sensitive but less linear, leading to coloration in the sound captured. Additionally, they tend to have lower high-frequency response like dynamic mics.

• Power Requirement: Similar to dynamic mics, they generally do not need phantom power, with few exceptions.

3. Condenser Microphones

• Mechanism: Consists of a thin diaphragm and a charged back plate, with sound pressure causing fluctuations in capacitance that generate voltage.

• Sensitivity: Condenser mics gain heightened sensitivity and detail due to their lighter diaphragm.

• Power Requirement: These microphones require phantom power (commonly 48V) to operate effectively.

• Examples: Include popular models like Neumann TLM 103 and Audio Technica 2020.

4. Tube Microphones

• Overview: A more advanced type of condenser microphone requiring high voltage from external power supplies to charge their internal components.

• Characteristics: Known for their warm sound due to harmonic amplification, but are delicate and expensive.

• Common Models: AKG C12, Telefunken U47, and U67 are premium examples that are highly sought after in studio settings.

Key Concepts

Operating Principles

• Condenser microphones provide better sensitivity due to their design featuring a light diaphragm and back plate arrangement creating voltage changes to capture audio.

• Dynamic microphones rely on a simpler mechanics involving magnet and coils.

Polar Patterns

• Definition: Refers to the microphone's pickup pattern, indicating which directions sound is captured from and how sensitive it is to sound from those directions.

• Types:

  • Omnidirectional: Picks sound equally from all directions.

  • Cardioid: Captures sound primarily from the front, resembling an upside-down heart shape.

  • Bidirectional: Sensitive to sound from the front and back, but not the sides.

  • Shotgun: Extremely focused pickup pattern, ideal for isolating sounds from a distance.

Microphone Selection and Placement

• Fundamentals: The selection and placement depend greatly on the source being recorded and the desired sound.

• Practical Considerations: Size and visibility of the microphone can affect performance anxiety in singers, while weight and fragility may also obstruct usability in live situations.

• Experimentation: Engaging in trial and error effectively teaches microphone placement to capture the optimal sound.

Recording Techniques

• Common Techniques: Including AB (spaced omnidirectional), ORTF, NOS, XY, and Mid-Side STL techniques are utilized based on the acoustics of the recording space and desired sound.

• XY Technique: Used for mono sources, providing width without causing phase issues, suitable for instruments like acoustic guitars.

• Mid-Side Technique: Involves the combination of cardioid and figure-eight microphones to create a stereo image from mono sources, allowing for later adjustments in mixing.

Conclusion

• Understanding various microphone types, their respective principles, and practical application techniques are integral for achieving desired audio outcomes in recording situations. Familiarity with the technological aspects as well as practical hands-on experience derives the most efficient audio fidelity.