Maneuvering Horn Microphones
Horns, such as trumpets, trombones, and saxophones, use similar miking techniques, so if you want to microphone horns, you don’t have to understand a ton of different techniques.
Understanding the role of the room
Because of the high volume levels of most horns and the fact that you mic them fairly closely, you don’t get a ton of impact from the acoustics of the room. Unless your room sounds really bad (for example, a small spare bedroom with carpeting and a low ceiling), you can deal with any room sound that bleeds into the mic.
If you have a small room that adds an unwanted sound to the instrument, surround the horn player with acoustic panels. You can experiment with using either the reflective or absorptive side of the panels to record the sound that you want. Generally speaking, err on the side of a more dead room — you can always add reverb later.
Making the most of the mics
For most horns, a decent condenser mic — large- or small-diaphragm — works well. If you want a richer tone, a ribbon mic is the way to go. In fact, you might want to pull out a ribbon mic first, and it will probably stay out until the session is over.
You can place the mic from 3 inches to a foot or more from the instrument, depending on the instrument and the sound you’re looking for. For example, a trumpet, because of its high sound-pressure levels (SPLs, or volume), would sound best with the mic a little farther away than the placement for a tenor sax. This is especially true with ribbon mics, because too much pressure can blow the ribbon.
Most horns generally sound better if the mic is placed just to the side of the bell (the part where the sound comes out). This keeps the SPL that the mic picks up low enough to avoid distortion and not blow your precious ribbon.
For some of the louder instruments, choose a condenser mic with a high SPL rating and/or a pad switch, or move the mic away from the instrument a bit. (A pad switch reduces the amount of sound — usually by 10–20dB — that the mic’s internal circuits process, allowing you to have a louder signal without distortion.)
If you want to record more than one horn instrument at a time (a couple of trombones, for instance), you can use a figure-8 condenser mic and position each horn player on either side of the mic. As an alternative, use one or more mics a couple of feet away from the players.