Microphone Types, Placement, Balanced Connections & Phantom Power

Est. 55 minCompetency: Choose and place microphones and apply phantom power correctly.

Learning objectives

Distinguish condenser, dynamic, and ceiling-array microphones.
Place microphones for best intelligibility.
Use balanced connections for mic runs.
Apply phantom power correctly and safely.

Vocabulary

Condenser mic: A capacitor mic needing power (phantom); sensitive, common in commercial AV.
Dynamic mic: A moving-coil mic needing no power; robust, less sensitive.
Phantom power: 48 V supplied over the audio pair to power a condenser mic.
Polar pattern: The directions a mic picks up (cardioid, omnidirectional, etc.).
Beamforming array: A multi-element ceiling mic that steers pickup toward the talker.

Lesson content

Microphone choice and placement drive the rest of the audio chain. The best DSP cannot fix a bad mic in the wrong place.

Mic types

Condenser — sensitive, needs phantom power; common for ceiling and tabletop in AV.
Dynamic — no power needed, handles loud sounds; common for handheld and some gooseneck.
Beamforming ceiling array — multiple elements that steer pickup; ideal for conferencing; needs power and DSP.

Placement

1Get the mic as close to the talker as the room allows (closer = better signal-to-noise).
2For ceiling arrays, follow the maker's spacing rules (e.g. one array per N seats).
3Avoid pointing mics at speakers to prevent feedback.
4Keep mics away from HVAC vents and noise sources.

Balanced connections and phantom power

Always run mics on balanced XLR for noise rejection over distance.
Condenser and array mics need 48 V phantom power; turn it on at the DSP/input.
Turn phantom on only when needed; do not hot-plug mics with phantom up.

Field caution

Dynamic mics do not need phantom and are usually unharmed by it, but do not assume — and never apply phantom to a device that cannot take it (some ribbon mics will fail). Confirm before energizing.

Worked example

A 10-person conference room: one ceiling beamforming array over the table (powered, 48 V phantom from the DSP) plus one gooseneck tabletop for the chair. All balanced XLR. Speakers are placed away from the mic pickup pattern to avoid feedback.

Implementation checklist

✓Mic type matched to use and power needs.
✓Mic close to talker; away from speakers and noise.
✓Balanced XLR for all mic runs.
✓Phantom on only for devices that need it.

Downloadable study guide

study-guide.txtcopy-paste ready

01. Condenser/array mics need phantom (48 V); dynamics do not.
02. Closer mic = better SNR; avoid pointing at speakers.
03. Balanced XLR for all mic runs.
04. Don't hot-plug under phantom; don't phantom devices that can't take it.