A condenser microphone uses a capacitor made of two charged plates — a thin diaphragm and a fixed backplate — to convert acoustic energy into an electrical signal. As sound waves move the diaphragm, the distance between the plates changes, altering the capacitance and generating a varying voltage.
Because the mechanism is so sensitive, condensers capture detail that dynamic microphones miss: breath, room tone, subtle instrument harmonics, and the upper frequencies that give vocals their 'air'. This makes them the first choice for studio recording of vocals, acoustic guitars, voice-over, and podcasting in treated rooms.
The sensitivity that makes condensers excellent in a studio makes them challenging in untreated spaces. Background noise, room reverb, HVAC systems, and keyboard clicks are all captured clearly. For home recording in a busy environment, a dynamic mic like the Shure SM58 or SM7B often produces cleaner results with less post-processing.
Large-diaphragm condensers (LDC) have a capsule over 25mm in diameter and are the standard for vocals and voice-over. Small-diaphragm condensers (SDC) are pencil-shaped and excel at acoustic instruments and overheads. All condenser microphones require phantom power (+48V) to operate.