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(Tips, Tricks, & Techniques provides how-to information about folk music and other topics. The main Tips page contains a list of additional tips.) A PRIMER ON MICROPHONES Last time, when trying to answer the question of whether to "go electric," I touched on dynamic versus condenser microphones. That's a subject both basic and complex enough to warrant this separate article. There are two basic types of microphones: dynamic and condenser. The main difference involves the circuitry that each uses, but their properties can also be quite different. Another parameter is a microphone's particular "pickup pattern" (which has nothing to do with pickups). Let's start with pickup patterns. A mike's pickup pattern is a map of how and from where it senses sound. Some mikes perceive sound equally strongly from all around them—front, back, sides. These mikes are called omnidirectional. Your basic layman-level electronics or stereo store sells these as entry-level mikes. They are perfect for taking lecture notes or recording a meeting. However, they can and do pick up sounds you as a performer don't want reproduced: audience noise (which you might find desirable if you want to include audience response in a live concert recording), sound from other instruments (which have their own mikes or amps), and sound from stage monitors. This latter type of sound is the most common cause of feedback—that audible howl that makes performers and listeners wince. There is a legitimate, on-stage use for omnidirectional mikes, however. It dates back to the early days of old-time and bluegrass radio and concerts. Back then, mikes were fairly expensive, and the technology was pretty much limited to omnidirectional pickup patterns. One omni mike could be used to amplify an entire band or singing group. Today, there are super-expensive large-diaphragm condenser mikes that do the same thing, but more accurately. Not surprisingly, they are most often used by orchestras and large bluegrass groups (as well as in the studio for ambience). The other type of pickup pattern is called unidirectional or cardioid. Cardioid mikes have a heart-shaped pickup pattern. That means they perceive sound most strongly from the singer's side (with the mike placed horizontally and pointed at the performer, we'll call it the front, although to the audience it's the back) and almost as strongly from around either side of the mike—but not from the back (audience side). The cardioid pickup pattern is usually effective up to about a foot or so away from the mike. There is a subclass called hypercardoid or supercardioid. They have an exaggeratedly heart-shaped pickup pattern and require much closer proximity of the singer or other sound source to the mike. Usually, the tighter the pickup pattern, the more accurate the sound, the better the rejection of unwanted sounds, and the more expensive the mike. Needless to say, a cardioid pattern is the pattern of choice for lead vocalists (or for up to three backing vocalists sharing one mike), as it is for musicians who want to mike the speakers of their amps. Dynamic or Condenser? Now, how about dynamic versus condenser? Well, dynamic mikes are the most common, fairly inexpensive, and most rugged for stage use. They do not require any internal or external power source. They are the workhorses of most working performers and house PA systems. The most widely used are the Shure SM-57 and -58 (as well as their Beta 58), and the ElectroVoice PL95A. Others to look for are the excellent mid-priced lines from Audix and Audio-Technica, and Shure's value-priced Beta Green series 1.1 through 3.1. It is not unusual to find 30-year-old Shure SM-57s still in use today in clubs. (Though the 57 is touted as being for instruments and the 58 for vocals, they are exactly the same mike except for the 58's ball-shaped capsule cover). Expect to pay (street price) as little as $50 on sale, up to $150 or so. Cheaper than that will always be lower quality (and often have a cable that cannot be detached); spending more will not buy you a perceptible improvement in sound or durability. The chief disadvantage of dynamic mikes is also (to some artists) an advantage. Though some of the better dynamic mikes can approach faithful reproduction of sound, they all color the sound to some extent (much like most brands of home stereo speakers). The "coloration" is almost always some degree of lower-frequency exaggeration. This of course is undesirable when recording classical musicians, opera singers, or any sound source that must be reproduced as faithfully as possible. Related to this, and especially in cardioid pattern dynamics, is the proximity effect, which is observed more readily for vocals and instrumentals. The closer a singer gets to the mike (especially to the center of the pickup pattern), the more the bass frequencies are emphasized and to some degree exaggerated. Not surprisingly, this is desirable for singers with lighter, thinner voices who need (and want) to add some power and "boominess" to their vocals. This makes such mikes appropriate for rock and blues lead vocals, and not so appropriate for backing vocals, folk, jazz, rap, or theatrical music. (Many singers, used to this proximity effect onstage, are surprised at first by how much lighter or thinner their voices sound when recorded with costly studio condenser mikes. They are simply not used to hearing their voices reproduced faithfully and clearly.) Condenser mikes are newer, invented in Germany in the middle of the last century. Their diaphragms (the membranes all mikes have that vibrate in response to sound and send the signal to be converted to electrical impulses) are sensitive, but require some type of power source to produce adequate volume. Most often this power source is an internal battery, but many PA boards have a power supply that provides phantom power to condenser mikes—a definite battery saver. If you require clear sound reproduction with as little extraneous "coloration" as possible, go with condensers. They are the mikes of choice in most studios and for broadcast applications. (Most studios, however, keep dynamics around for when sound coloration is desired.) Be forewarned: Condenser mikes are almost always more expensive and definitely more delicate. If you must tour with them, coddle them—always keep them in their cases (foam-lined, if possible) and never toss them around the stage. And, since they usually have on-off switches (as do some dynamics), be sure to shut them off when not in use—unless you have phantom power or enjoy buying batteries by the gross (or own shares of Duracell). Condensers can cost from a little over $100 up well into the thousands. They come in two basic types: large and small diaphragms. Large-diaphragm condensers are most often used for recording vocals and radio applications (and the less delicate ones for bluegrass ensembles). The small-diaphragm ones are sometimes called pencil mikes: you can find them most often in studios for miking instruments and in concert halls for recording orchestras, section by section. (Those skinny mikes you see dangling from the rafters over the stage at Orchestra Hall during CSO concerts are small-diaphragm condensers.) Not surprisingly, they are also the mikes of choice for direct-to-disc and digital recordings. Their smaller size doesn't always translate into lower prices. They can also be used in various configurations for stereo recording (x-shaped and v-shaped are popular placements for this purpose). If you are a lead or solo vocalist and want your voice amplified as clearly and colorlessly as possible, and you're willing to take exquisite care of them, then condensers are for you. And of course, every serious home studio ought to have a pair. Whatever mikes you end up buying, take several common-sense measures to ensure years of happy and trouble-free use:
• Always
store mikes with on-off switches in the "off" position. Transformers A word about transformers: One distinction I left out earlier was impedance. Mikes are either high ("hi-Z") or low ("low-Z") impedance. Impedance is the resistance of a transducer (mike or speaker) to a given amount of electrical energy, expressed in ohms (hence the science-fiction-fan T-shirt declaring, "Earthlings: Resistance is useless...if less than 1 ohm"). Which type is more desirable? Well, it shouldn't surprise you to learn that more expensive mikes are almost always low-Z. Low impedance allows you to use longer cables without signal loss and usually provide more faithful reproduction of sound. You can tell a low-Z mike or input from the end of the cable it uses and the jack into which it's plugged: both have a type of three-prong-or-hole connector called XLR or balanced. Balanced cables are also less prone to interference or hum. On the other hand, hi-Z mikes are cheaper and widely available in stores with lower price points (in fact, they're ubiquitous in places like Radio Shack or Best Buy). Why buy them if you can't use a long cable without either interference or signal loss? Well, because their cables terminate in a standard 1/4" mono jack (like on a guitar cable), they can be used in soundboards and amps that have only 1/4" jacks. Thus, if all you have in the way of a PA is a guitar amp or cheap disco mixer, you can plug directly in. So what's a transformer and why would you use one? It's a device that takes a low-Z signal and turns it into a hi-Z one ("step-up" transformer), allowing you to plug an expensive low-Z mike into a cheaper amp with no XLR jacks; or takes a hi-Z signal and attenuates (weakens) it ("step-down" transformer), letting you plug a cheaper mike with a 1/4" plug into a balanced XLR output (and if placed close to the mike, letting you use a longer cable run). Transformers run anywhere from $25-50 or so, and belong in every accessory bag, along with at least one extra of every type of cable you need. So plug in and get out there and perform! Main Page • List of Tips • Contact Sandy Copyright © 2000, 2001, Sandy Andina, All Rights Reserved |
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