Microphone Techniques and Placement Flashcards

What is the 'Blumlein pair' stereo microphone configuration?

Answer: Two figure-8 (bidirectional) microphones crossed at 90 degrees, capturing a wide and accurate stereo image with natural out-of-phase side information

A Blumlein pair uses two figure-8 microphones with their capsules coincident and angled 90 degrees to each other (±45° from center). The combination of the front and side rejection of each capsule produces a very accurate, wide stereo image with excellent mono compatibility.

For recording a grand piano, what is the advantage of using an 'X-Y pair' placed inside the lid?

Answer: It provides a phase-coherent stereo image of the full keyboard range with good mono compatibility due to the coincident capsule placement

An X-Y pair inside the piano lid (with the piano's lid open on the long stick or short stick) captures a direct stereo image of the keyboard width with both capsules at the same point in space, ensuring phase coherence and strong mono compatibility — important when the mix may be played in mono.

What is 'side address' vs. 'end address' (top address) microphone orientation?

Answer: Side-address microphones pick up from the side of the capsule (perpendicular to the body); end-address microphones pick up from the top of the body in line with the capsule

Side-address (or side-fire) microphones, like most large-diaphragm condensers, have their pickup axis perpendicular to the body — the sound enters the side. End-address (top-fire) microphones, like most small-diaphragm pencil condensers and dynamic microphones, pick up from the tip/top end of the body.

What does 'off-axis coloration' mean in microphone polar behavior?

Answer: The change in tonal quality and frequency response when a sound source is positioned away from the main axis of the microphone

Off-axis coloration describes how the frequency response of a directional microphone changes as the sound source moves away from the primary pickup axis. High frequencies are typically attenuated more at off-axis angles, causing off-axis sounds to sound dull compared to on-axis.

When recording a loud guitar amplifier with a dynamic microphone, how does moving the microphone from the center of the speaker cone to the edge affect the sound?

Answer: The center of the cone produces a brighter, more detailed sound; the edge produces a warmer, rounder tone with reduced high-frequency content

The center of a speaker cone is where high-frequency dispersion is most direct and focused, producing a brighter, more aggressive tone. The edge of the cone produces a softer, warmer sound with reduced high-frequency content. Engineers adjust placement between center and edge to tune the tone.

What is a 'boundary microphone' (PZM — Pressure Zone Microphone), and what is its primary use case?

Answer: A microphone mounted flush against a flat surface that captures sound in the pressure zone, free from reflections and with a hemispherical polar pattern

A boundary microphone (PZM) is mounted on a flat surface (table, wall, floor). In the pressure zone directly adjacent to the surface, direct and reflected sound arrive in phase, resulting in a hemispherical pickup pattern free from comb filtering artifacts. They are used for conference rooms, piano recording (inside the lid on the soundboard), and theatrical applications.