This is a guest post by Kyle M. Bagley.
You can get a great trombone or trumpet recording with an array of mics and methods, including several low price options. As in many cases, the sound of the player themselves and the mic position are more important than the microphone in capturing a great recording.
This article focuses mainly on close-miking players and individual sound. For more on miking a section or far-miking brass players, read Part 1 in the series.
Understanding Brass Instruments
Sound coming out of a brass instrument is relatively linear, or directional. You can think of the bell of a brass instrument as a speaker. The loudest sound comes from the center of the bell, and the sound will get quieter and change somewhat as you get farther from it.
There is also some sound that emanates from the bell itself, usually high frequencies.
Changing the axis of the microphone, or pointing it at an angle rather the directly at the bell will drastically change the character of the instrument on recordings by varying amounts of these two sound sources.
On-Axis or Off-Axis?
What kind of sound are you looking for? Consider this before you even set up a mic stand. Do I want a piercing sound or mellow? Bright or dark? Will the brass be loud, a focus of the music, or background? Moving lines or long tones? If you don’t know, ask the band.
As stated above, the loudest sound comes from a mic pointed directly at the bell. This sound is also the harshest.
As you get farther away, the sound will get quieter, more mellow, and individual notes and articulations will be less clear. A good range of close mic placement is from one to four feet away. It is also important to note that distance mixes in more room sound, which can be counterproductive if you are already using room mics.
Pointing the mic off-axis will achieve some of the same results, but with a new set of variables.
As you increase the angle of axis, you increase the amount of “bell” sound you hear, and decrease the direct sound. In this way, you can make a sound darker and mellower without decreasing the volume or increasing room sound.Many engineers consider it bad form to record directly on-axis.
Another changing variable that comes with off-axis miking is wall reflection and bleed between microphones.
As you point a mic off-axis, you are not only pointing it at a different part of the instrument, but a different part of the room. Is another sound bouncing off the wall the mic is now pointed at? The bell of an instrument is circular, so the angle is the same whether you point it up, down, left, or right.
Consider this while setting up the room and other instruments. Many engineers will use foam around the mic or baffles between the players to avoid problems when recording off-axis.
Be sure to explain your methods to the players, and give them an idea of what you are doing with the mic. As with singers, not every musician will know how to use a mic, and may think your placement is accidental or unimportant.
Brass Players and Tone
Brass players, more than any other instrument, rely heavily on the musician, and not on the instrument for tone quality.
The sound is actually created by the buzzing lips of the player, and amplified by the instrument. Understanding this is important for an engineer and how they interact with the player.
This means that the tone, tuning, and volume can change throughout the session, as the player gets “warmed up” or fatigued. It also means that note attacks and articulations are different player-to-player or on each take. Long sessions can be very taxing, and engineers need to be constantly listening for the sound they want
A general go-to starting point for brass instruments is a small diaphragm condenser mic. They usually have a frequency response that is tuned well to brass, have good directionality to prevent bleed, and are easy to point and focus on specific areas of the bell. Again, price is not a huge factor here. I have a Sterling Audio ST31 ($99) that I love on brass instruments, and countless others have been used to the same effect.
Large diaphragm condensers and vocal mics can also be used, although fine placement can be more difficult. Be sure to check the frequency response, so you are not boosting any areas of the sound that would result in tone.
If no condensers are available, or they are being used for room/section mics, dynamic mics like the Shure SM57 will do just fine. Again, the players’ sound and the mic placement are far more important.
Kyle M. Bagley attended Berklee College of Music, and currently lives in Rhode Island as a musician and studio owner. See more of his work at http://www.kylembagley.com
Image by: atiredmachine