The EM Poll

Capturing Big Sounds

Nov 1, 2007 12:00 PM, By Myles Boisen

           

All about large-diaphragm dynamic microphones.

Acoustic bass. I have found that a condenser mic is generally the best choice for recording acoustic bass, due to its faster transient response and better high end. However, a large-diaphragm dynamic can also deliver a satisfactory stand-up bass sound. And due to its lower susceptibility to feedback, this type of mic may be the best choice for a bass in live-sound reinforcement.

Miking the instrument in front of the bridge typically offers the most balanced and representational sound. But usually this kind of placement has to be at a distance of one foot or so to accommodate bowing. Miking the bass in front of the f holes provides more gain and better isolation but tends to favor a boomy and uneven timbre, with some notes coming out much louder than others.

Electric guitar. One of my favorite guitar mics is the large-diaphragm Sennheiser MD 421. The tonality of this mic, which blends high-end cutting power with low-end punch, seems perfect for many of my guitar recording needs. All of the aforementioned tips for recording a bass cabinet are also applicable here.

A great guitar-amp recording trick is to use the 421 and a ribbon mic side by side, directly in front of the speaker cone and about four to six inches back from the amplifier's grille cloth. To reduce the effects of phase cancellation, the diaphragms of the two mics should be as close together as physically possible.

Angling each of the mics slightly toward the outside edge of the speaker and then panning the two guitar tracks apart in the mix produces a stereoized sound that is bigger, airier, and more commanding than the conventional single-point guitar sound. This mic technique can also add excitement to any source run through a conventional amp: organ, synth, electric piano, amplified acoustic instruments, and samples.

Brass and sax. Condenser mics often have an exaggerated high-end response, which can make them less than ideal for recording brass instruments such as tuba and trombone. Dynamic mics (and ribbon mics as well) tend to soften the high-end sizzle on these instruments, making them easier on the ear when close-miking.

FIG. 4: Position the mic at the edge of the bell of a brass instrument to capture low end while mitigating harshness. Credit: Myles Boisen

Positioning the mic at the edge of the bell, rather than aiming it down the center of the bore, captures a more complex sound with superior low end and less harsh highs (see Fig. 4). Low brass instruments can also put out deafening SPLs, which a dynamic mic can easily handle.

The Sennheiser MD 421 and Electro-Voice RE20 are large-diaphragm mics commonly used on saxophones and brass. When a suitable condenser mic is not available, this type of microphone makes a good alternate choice for studio work.

The aforementioned transducers are also staples of any decently equipped live-sound setup. A large-diaphragm dynamic provides needed low-end heft, due to increased proximity effect as well as the boosted bass response of the mic itself. These mics also work well for less common wind instruments such as bass flute and bass clarinet.

Vocals. It's no secret that the huge, booming tone of a classic radio announcer is created by working a large-diaphragm dynamic mic as close as possible to deliver maximum intelligibility and proximity effect. Most condenser mics are too susceptible to popping for this kind of trick, and ribbon mics may well be damaged or destroyed by plosives this way.

In the studio, rock and rap vocalists in particular may be most comfortable with the freedom of movement and familiarity that a handheld dynamic mic provides. And for beatboxing, a dynamic mic is the only way to go. The resulting sound, though it may lack the transparency and air of a condenser mic, is often punchy, well defined, and easy to place in the foreground of a mix.

Unconventional Uses

I have put large-diaphragm dynamics to work on a number of unusual jobs. These include miking the lower rotating bass speaker of a Leslie cabinet, tracking a didgeridoo, and using one as an experimental drum-room mic.

I obtained unusual coloration using a large-diaphragm dynamic as an ambient drum-room mic: I placed it inside the shell of a floor tom, which was laid on its side on the floor a few feet away from the drum kit. This technique tends to emphasize a few boomy low frequencies. But with some attention to placement and drum tuning, it can add a unique and hugely resonant timbre to the sound of the kit. I have also gotten some wild sounds by placing drum-room mics inside metal tins, canisters, and garbage cans.

Big and Bad

Although it's tempting to think of large-diaphragm dynamic mics as being for bass drum and other limited uses only, they form a versatile class of transducer with numerous potential applications for recording. Some models offer superior sonics and deluxe features applicable to instrumental and vocal use. And while dynamic mics have a reputation for being rugged and affordable rather than sonically sophisticated, in many cases they offer distinct advantages over the delicacy and flat response of condenser and ribbon mics.

Myles Boisen runs Guerrilla Recording and the Headless Buddha Mastering Lab in Oakland, California. He can be reached through his Web site at www.mylesboisen.com.