Miking an Amp

Anyone recording an amp with a microphone makes a surprisingly consequential decision: the position of the microphone changes the sound more than most expensive gear upgrades. A basic understanding saves a lot of frustration.

Microphone types — Dynamic microphone: rugged, handles high levels, often pleasantly emphasizes the mids — the standard right at the guitar speaker. Condenser microphone: more detailed and treble-rich, more sensitive — often as a second mic at some distance for "air" and room.

Prominent references — At the guitar amp the Shure SM57 is by far the most-used standard (dynamic, rugged, mid-forward); the Sennheiser MD421 and the ribbon Royer R-121 stand for fuller or softer variants. As a room/second mic, large-diaphragm condensers serve. Reference points, not a ranking — the SM57 is widespread, not "the best".

Position — the two axes — Near vs. far: right at the grille the tone is direct and dry; with distance, room and air come in. Center vs. edge of the cone: toward the speaker center (dust cap) it sounds brighter and more biting, toward the edge darker and warmer. Between these points lies a whole palette — audible within a few centimeters.

Phase trap — With two microphones the signals can partly cancel depending on distance (thin, hollow sound). So choose distances deliberately and check the phase.

In practice — Searching for the best spot with an ear at the speaker and setting the mic there is a proven starting point. One microphone placed right beats two placed wrong.

There is no "correct" position, only the one that hits the desired sound. Miking is a craft of trial — and the cheapest "tone control" you have.