How Microphones Work
A dynamic mic is literally a speaker in reverse. Sound waves push a diaphragm, a coil moves in a magnetic field, and current flows out. Same physics, opposite direction.
Speaker in Reverse
Dynamic microphones work exactly like speakers, backwards. Sound waves move a diaphragm attached to a coil suspended in a magnetic field, generating an electrical current. A speaker takes current and produces motion; a dynamic mic takes motion and produces current. Same physics, opposite direction.
Condenser Microphones
Condenser mics use a thin membrane as one plate of a capacitor. Sound vibrates the membrane, changing the capacitance and producing a voltage signal. They require phantom power (usually 48V) to charge the capacitor. The result is more sensitivity, extended high-frequency response, and a wider dynamic range, but they are more fragile and more expensive than dynamics.
Ribbon Microphones
A thin aluminum ribbon suspended in a magnetic field moves with the sound wave, generating current directly. Ribbons are naturally figure-8 (bidirectional) because the ribbon responds to pressure differences between its front and back. They are extremely delicate but have a uniquely smooth, warm character with a natural high-frequency rolloff.
The Mic as EQ
Every microphone has a unique frequency response curve. An SM57's presence peak at 5 kHz shapes the sound before any processing happens. A Royer ribbon rolls off highs naturally, lending warmth. A U87 condenser adds "air" with its extended high-frequency response. Choosing a mic IS choosing an EQ curve.
Try it: switch between mic types and hear how each one colors the same source signal.