Brass instrument's sound primarily comes from the vibration of the bell. Additionally, the sound of brass instruments are heavily effected by the room your playing in. Typically, you want to avoid placing the microphone directly in front of the instrument bell in order to capture more of the room sound.
Brass microphone placement
Brass instruments require more distance from the mic to sound natural; this gives the sound space to develop. Most of the following placements are focused on achieving an ideal distance between the microphone and the instrument.
- Don't close-mic the bell; record the room sound.
- Position the mic below the player's line of sight
- Point the mic off-axis from the bell.
Trumpet
Technique 1: Place the mic about 4 feet away, directly in front of the instrument.
Technique 2: Place the mic 3 to 4 feet away but above the bell and aimed toward the mouthpiece
Trombone
Place the mic about 2 feet away off-axis of approximately 20 to 30 degrees of the bell.
For a more aggressive sound to cut through a dense mix, set the mic about 18-24 inches directly in front of the bell.
Tuba
Set the mic about 2 feet over the top of the bell and about 15 degrees off-axis of the bell. If it sounds too "blatty," aim the mic more off-axis.
French Horn
Technique 1: Set the mic 2-4 feet from the bell at a height that matches the top edge of the bell. Aim the mic towards the center of the bell.
Technique 2: Set the mic about 1-2 feet over the player's head pointed straight down.