THE MICROPHONE MAZE

THE MICROPHONE MAZE

EXTENSION CHORDS

by Allen Hester

Got a question for ya: What do the Watergate tapes and Woodstock have in common? The answer? Microphones. Every one of us, every day, uses some kind of a microphone. Usually, and in the vast majority of cases, it is the microphone in the telephone receiver that we use. When we watch a television newscast, or listen to a radio, we are listening to voices that are speaking into some kind of microphone. And yet, even though the microphone, in all its variations and permutations, is as common as Kleenex, people still are confused about what microphones do, how they work, and why some of them cost $19.95 and others cost in the hundreds of dollars.

Basically, a microphone is a transducer, an energy converter. Microphones convert acoustical energy to electrical energy. This conversion can be achieved in a variety of ways, but for our purpose here all we need to be concerned with are two kinds of mikes: Dynamic and Condenser.

Dynamic mikes have a diaphragm with a voice coil attached near the center. Both the diaphragm and the voice coil are surrounded by a magnetic structure to which the coil is connected. When acoustical energy (a voice, for example) is applied to the diaphragm, this in turn moves the coil, which causes an electrical current to flow as the lines of magnetic flux are cut. Dynamic mikes are characteristically rugged, reliable, and require very little maintenance. They can deliver a wide frequency response, or they can be designed to emphasize certain areas of the frequency range. Because of their ruggedness, they are most often used in live sound reinforcement applications, but dynamic mikes can also be used, in recording.

Condenser mikes have a capacitor structure that consists of a thin membrane opposite a perforated plate. Sound pressure against the membrane causes it to move, which changes the electrical output of the circuit. Some condenser mikes require an external power supply to polarize the capacitor circuit, and these are most often used in studio applications where they receive very careful handling. The other common type, the "electret" condenser mike, is made with a polarizing voltage built into the diaphragm, or the plate, so that the circuit has an electrical charge. This eliminates the need for an external power supply, but a small battery which is connected inside the mike itself is required to power the FET circuit that matches the impedance (in ohms) of the mike to the amp into which the mike is plugged.

If all that sounds complicated, believe me, that is just the tip of the iceberg, and there is enough math involved in microphone design to send a good algebra student to the crazy house. The thing to remember is, when you compare one mike to another, you need to make sure you are comparing similar mikes. They may all look the same to you, but they can be as different in design and application as night

and day. Most of the microphone manufacturers have free info available about mikes, and the terminology and application is clearly explained. If you don't already know what "omnidirectional," "cardiod," "proximity effect" and "impedance" mean, you may have a hard time making the best choice in your next mike purchase. The reason this is more important than ever before is because there are more mikes to choose from now. Aside from the established names in microphone manufacturing, there are a number of new names coming into the market. The cost of good quality mikes is coming down a bit, despite the general trend of rising prices everywhere else, so it is going to be harder to make a decision on which mike is right for you. The best thing to do, if you don't know a lot about microphones or technical terms, is to go to your local music store, and bother the sales people until they give you some answers. If you can stand the eye-rolling looks you get, you'll probably learn something. Anyway, so much for consumer advice. Here are some mikes you should check out.

Beyer Dynamic is one of the established names in microphones, and they have a reputation for top quality. Beyer has just introduced a new, low-cost model, the M 300N(C). This is a low-impedance mike with a directional cardioid pattern. "Cardioid," meaning "heart-shaped," tells you that the mike picks up sound from in front of it, while rejecting sound coming from the rear of it. The low impedance means it can have a long cable with no hum and no loss of signal. This type of mike is what most rock 'n' roll vocalists use—dynamic, cardioid, low impedance. The Beyer M300 N (C) can also be used to mike instruments and/or amplifiers. The frequency response of this mike has been tapered, or shaped, so that it has a low-frequency rolloff—a deemphasis of bass—a high frequency rise— a treble boost—and a boost mid-range presence. The M 300 N(C) has been carefully designed for use' by rock singers who want a bright sound, even when they sing very close to the mike. In fact, it is a characteristic of most rock singers to "eat" the mike, meaning that they sing with their mouths touching it. When you get that close to a mike, a phenomenon called the "proximity effect" occurs. All this means is that the mike sounds more bassy, because as you move in closer, the bass frequencies are emphasized. So, with that tendency of rock singers (to sing close to the mike) in mind, Beyer Dynamic designed this particular mike with a bass rolloff, so that the mike will stay bright at close range.

Another thing that happens when a singer "eats" the mike is that it will make a popping sound when certain hard consonants are shouted into it. To prevent this annoying popping sound, Beyer has included a "pop filter" in the M 300 N(C).

Combine these features with a rugged black matte aluminum case, a silver wire mesh basket, and a sturdy low-impedance cord, and the M 300 N(C) stacks up as a superb choice for the musician or vocalist in search of his/her first' professional microphone. The West German-made mike comes with carrying case, swivel mount and cord.

Probably the best-known name in vocal and instrument mikes for the basic rock 'n' roll band on the road is Shure. If I had to guess which mike is best-known, I'd say Shure, but I really don't have any computer print-outs to substantiate my speculation. But Shure has been around a long time, and the Shure SM57 and SM58 have become "workhorse" mikes for rock bands over the past few years. Like Beyer Dynamic, Shure has a great reputation for quality, and now Shure has just introduced their new line of low-priced mikes, the Professional Entertainer (PE) Series.

There are nine basic designs in the PE Series, with variations and optional impedance/ cable configurations available for each basic model, bringing the total number of mikes in the series to 21. Each one is specifically recommended for a particular type of instrument and/or vocal application.

The PE 75 Series, of which there are two models, one with cable, one without (both are low-impedance), is recommended for the lead vocalist for several reasons. The PE 75 has a tight cardioid pattern, meaning that it does not pick up off-axis sounds, enabling the singer to move around the stage without fear of feedback caused by another instrument picked up by the mike. This has the most pronounced high end and presence peak of any of the PE series, so the singer can get crisp highend sounds without having to strain his vocal chords too much. However, in direct contrast to the Beyer M 300 N(C), the PE 75 has a bass boost instead of a rolloff. This is neither good or bad, it is just that the two mikes are designed differently. Obviously, if the singer has a weak voice in the low register, then the PE 75 is the choice to make.

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The PE 75 is a very sensitive mike, again a plus for the young singer whose vocal power is perhaps not fully developed, or for the old pro who sings six nights a week and needs all the help a sensitive mike can provide. In either case, the PE 75 will make the singer's voice sound richer and more dramatic. The PE 75 also has an internal shock mount which reduced on-stage vibration and handling noise, and this particular model also has a lockable reed on/off switch. This mike comes complete with a swivel adapter, a vinyl gig bag, and an optional low impedance cable.

A new name in the microphone field is Pearl, a company which already makes a fine quality drum set and other products, and Pearl has entered the market with a group ot dynamic and electret condenser mikes that are suitable for stage and studio use. The CR-57 is a professional quality studio phantom powered electTet condenser mike. The big advantage that electret mikes have in general is that they can handle transient peaks or "spikes" (sharp peaks in the frequency response pattern) with little or no distortion. This mike also has an IC and silicon transistor amplifier built into it, and it has no output transformer, so the CR-57 has low distortion over the entire frequency range.

A built-in attenuator switch allows the selection of 0 or 12dB, which increases the maximum sound pressure level up to 150dB and enables the user to mike a bass drum at 48 volts DC operation. The key word here is flexibility, and a good engineer can use the CR-57 for a wide variety of uses. Another feature that gives the mike flexibility is a built-in bass rolloff switch. Whereas a choice has to be made between the two dynamic mikes previously mentioned when it comes to bass response, this mike offers the user the option of a 6dB per octave rolloff below 200Hz. So here again, this mike is not necessarily "better" than the Beyer or the Shure. It all depends on the type of voice or instrument being used, and the situation, whether it is live performance or studio work.

So here we have a look at some new mikes from several well-known companies. The thing to remember is that each mike is designed differently with a specific kind of input source and/or environment in mind. To compare prices alone is not enough; the buyer has to have some idea of what microphones do and how they differ—whether they are dynamic, condenser, electret condenser, unidirectional, omnidirectional, and so forth—and the buyer must have some idea how the mike will be used. Whether on the stage or in the studio, whether for vocals or instruments, and so forth—all of these things, right down to the individual players' style, are factors that determine what the most appropriate mike would be. No one mike is "perfect" for every job. And any good studio engineer will tell you that sometimes, a really unique sound can be achieved by using a mik? in the "wrong" way, or by using a mike that is not really "studio quality" for a special effect. Most studios have a box of old mikes stashed away somewhere for just that reason, and musicians are constantly experimenting with them to get their own distinct sound onto tape.