A Primer On Choosing Recording Microphones
As any truck-loading, stick-wielding veteran knows, a drum kit is more than just an axe. It’s a complex creature composed of singular, closely arranged voices. This makes capturing the lot on tape (or hard disc, these days) a bit more challenging than simply finding and using that one favorite studio microphone. Mikes have as much individual attitude as you and your drum set. Choosing the best match for your particular vibe is an important part of achieving your recorded sound.
Of course, starting with a well-tuned drum kit and having your chops together is the main priority for any session, because you can’t hide when you’re under the aural microscope. If your kit is a pile, and you haven’t done your woodshedding, then it matters little if a vintage Neumann U47 FET is on your bass drum and a stereo pair of premium Schoeps is overhead. But if your kit is primed and you’re on top of your game, a bunch of Shure SM57s could do you justice. Of course, if you’re a slamming drummer, you could probably make a set of five-gallon buckets and cardboard boxes sound good under a bevy of Radioshack specials.
That said, whether you’re going into a big commercial studio or a smaller project studio, a little background knowledge of microphones can help you achieve the most important facet of any recording – a good drum sound. Of the many transducers available today, some are specifically designed to record drums, while other versatile models cover a variety of applications. A mike that works well on a kick drum won’t necessarily be the best choice for cymbals, and vice versa.
Variables that influence your microphone choices are the genre of music being played, the room ambience, isolation, your drumming style, and drum sound. Anywhere from two to over a dozen mikes can be used to represent your kit, and which ones and how many you use depends on the sound you’re going for, the number of tracks available, and the sound of the room. Microphone placement is also a factor, but that’s another subject that has addressed in past issues of DRUM! [see “Recording Tips” from Jan/Feb 1997 and “Onstage Percussion Miking Tips” from Mar/Apr 2001]. Instead we’ll describe basic types of mikes and look at which are appropriate for drum set applications.
Meet The Mikes
Microphones can be broken down into three basic types: dynamic, condenser and ribbon. Nine out of ten times you’ll reach for dynamic and condenser mikes for your kit, but ribbon mikes can work in certain cases. Of dynamics and condensers, both large and small diaphragm versions are available. Generally speaking, larger diaphragm mikes tend to pick up lows well, while smaller diaphragm mikes exhibit better transient response due to lower mass, enabling them to clearly represent the leading edge of a sound.
Dynamic mikes are designed so that a coil attached to the diaphragm, moves through a magnetic field in proportion to sound vibrations affecting the membrane. This action induces an electrical current in the coil, creating the signal used by the audio gear. The mechanics of a dynamic make it durable and able to handle high SPLs (sound pressure levels), while limiting to a certain degree both its frequency and transient responses. You’ll find dynamic mikes in live sound reinforcement because they can handle the abuse, but they’re also a favorite for many drum-miking applications in the studio. Examples include the ubiquitous Shure SM57 and SM58, Sennheiser’s MD421, Electro-Voice’s RE20, and AKG’s D112.
Condensers, sometimes called capacitor microphones, operate on the principles of capacitance. A capacitor is comprised of two conductive plates separated by an insulating dielectric. In a capacitor microphone, the back plate must be charged, and therefore requires phantom power (tube condensers have their own separate power supplies). Voltage changes are caused by the movement of the conductive diaphragm against the charged back plate, in reaction to sound vibrations. This action translates into an electrical audio signal.
There are both large and small diaphragm versions of this type of mike. These mikes have an extended frequency response and a high sensitivity. They tend to be more expensive and not as durable as dynamics, and less able to handle high SPLs, but their response characteristics allow them to capture a higher degree of detail.
Ribbon (or velocity) mikes generate a signal through a crimped conductive ribbon suspended between two poles of a magnet. Most of these mikes have a bi-directional pickup pattern, although unidirectional models do exist. The element is typically delicate, although newer models are more robust. Ribbon mikes are not recommended for close miking drums, as the high SPL can damage the fragile ribbon. But these transducers have an excellent, warm high-end transient response, which can be an asset when choosing an overhead or room mike for a less bombastic situation.