MICROPHONES DON'T GET NO RESPECT!

MICROPHONES DON'T GET NO RESPECT!

EXTENSION CHORDS

Chip Stern

by

Whether your vantage point is onstage or in the audience (and not on a guest-list pass, either), its invariably the same dreary dance. Thousands of crazed fans frothing before the opening bell, the stage all aglitter in lights and equipment...and equipment...and more equipment.

There are the obligatory stacks of amplifiers; high risers groaning under the girth of mega-drum kits and a dozen cymbals; scores of flash guitars and basses waiting obligingly before each 200 watt monolith.. .a blonde on each arm, a boutonniere in your buttonhole and a pound of tracer in the tool box.

But wait! Theres been a, uh...we//, a miscalculation of sorts. Seems that no one bothered to invest the time or money in selecting the proper performance microphones. Yeah, well, we use whatever house mics the local sound contractor or promoter provides," a little voice is heard to whimper by way of a cop-out, pausing only to snarf up a second helping of Dr. Rise Times high impedance powdered protoplasm.

Good thinking, schmuck.

Youve just dedicated the better part of five years rehearsing, spent tens of thousands of dollars on instruments, signal processing, electronics, even your own van and P.A. Youve endured all the multitudinous inconveniences and petty humiliations THE BIZ inflicts on those who would be performers. And when you finally get a chance to play a decent venue, whatcha do? Abdicate the most critical part of the signal chain — instrument and vocal mics—by allowing some stranger to slap the wrong mic (well, their idea of the right mic, anyway, or whatever they happen to have handy) on your kick drum, guitar amp, bass amp, keyboard amp and vocalist.

Only later, licking your wounds, does it occur to you that the sound you got onstage was critically altered...re-mixed...distorted by the type of microphones and manner of micing techniques; that the undifferentiated sea of sludge and low-end rumble the audience experienced (rather than heard—the aural equivalent of dog breath) could have been avoided. Ah, but youll have plenty of time for reflection now, beanbag, because your vocalist shouted her voice raw—cant even talk—and theyve found another band to open all the upcoming big dates. Think about that when youre back home pumping gas.

The point is that where rock n rollers can spend hours debating the relative merits of a 58 Les Paul vs. a 62 Stratocaster, the Marshall tube sound vs. the Mesa Boogie, the Prophet vs. the Oberheim, the distinctive frequency characteristics and sound signatures of microphones remain largely unexplored. Why?

Perhaps because were talking about the difference between the way something sounds, and the way something hears, because as surely as your ears and my ears hear sounds differently, so too do microphones perceive musical information in their own unique ways. Theres nothing even vaguely objective about the way microphones hear. Whether subjectively coloring the sound in user-pleasing manner or allowing the truth, the whole truth and nothing but the truth to shine transparently through, microphones can make or break the sound of your instrument and the overall presentation of your music.

You have to understand the physics of acoustics and the microphone, and to some extent you have to understand the physics of the musical instruments," Geoff Langdon of Sennheiser asserts. Once you understand these things, and have a clear preconceptualization of the sound you want, you can create a situation where you get that sound. Whats missing in the output of a microphone cannot be created later in the chain; even more important, is whats missing in the musical instrument cannot be created later in the chain, and cannot be corrected for by the microphone.

Ive done a lot of microphone seminars, and people always want a cookbook approach: which mic do I buy, and where do I put it exactly to make a golden record? It doesnt work that way." Jeff Levy of Beyer concurs. Microphones are very subjective instruments. You have to learn to listen, and to know what to listen for. People generally are not thinking ahead as to what theyre going to be using the microphone for: whats, the frequency response of the source; whats the sound pressure level—how much microphone do I need? People dont know what microphone to use in what application and for what reason. And then theyll buy a microphone without bothering to audition it—those people deserve whatever they get."

Dick Ravitch of AKG chimes in to this litany of despair by observing that when it comes to microphones People dont know enough about mics, and whats worse,they dont seem to want to know." Maybe they just dont know that they dont know, or dont know why they should know. So in the interests of improving rock n roll music, and your ability to project the truest image of your sound to an audience, CREEM and Extension Chords will now undertake—as painlessly and straightforwardly as possible—to provide some basic reference points towards understanding the function of microphones, common mistakes and misconceptions regarding their application and handling, and some sense of how to best use them. Too much information to possibly be contained in one article, but herein, a consumer guide—not a shopping list—to microphones; the beginnings of an ongoing discussion in these pages which in future issues will zero in on specific models and applications. But first things first...

What is a microphone?

A microphone is part art and part science in application and design. It is not an accessory, even though thats how a lot of dealers and consumers view it: to wit, where many of the aforementioned aspiring bands will have P.A. mixing boards running anywhere from $2,000-$20,000, theyll purchase mics only as an afterthought. Same thing with purchasers of home stereo systems vis a vis the phono cartridge. Its as if, dear friends, De LAWD spent the sixth day creating the wind, thunder, lightning, birds and the oceans roar, but took the seventh day off without giving us ears.

Now the difference between your ear and a microphone is that instead of changes in sound and air pressure vibrating your eardrum, it vibrates a diaphragm within the microphone housing. This diaphragm is refered to as a transducer element, and the way in which it is designed to respond distinguishes its generic type (more on that in a minute).

The three basic generic types of microphones purveyors of brain damage musical performance need be concerned with are dynamic (or moving coil), condenser, and ribbon designs, of which dynamics are by far the most commonly used, due to their ruggedness and ability to withstand high sound pressure levels. What differentiates these design principles is the way the transducer elements transform acoustical energy into electrical energy. The quality of the way they hear, tells you something about how theyre going to sound, what bass/midrange/treble frequenies, colors and sonic tradeoffs to expect. Mike Petterson of Shure cheerfully suggests that CREEM readers think of dynamic, condenser and ribbon qualities as BALLS, DETAIL, and MELLOWNESS respectively.

Keep that concept on hold for a second and consider this equally important one. Weve just suggested that theres a certain color...musical timbre to the way these musical instruments vibrate. Alright?

Now, instead of zoning out on this (or succumbing to the temptation to ask But is it LOUD?!"), think about how microphones hear. Put on a record, sing through a P.A. or mic up your guitar amp and run it through the P.A. Nanu nanu. Good. Now defeat your biological stereo output—stick a finger in your ear. Put your other ear adjacent to what youre micing and youll hear what the mic hears and the way it hears. Are you cognizant of the spatial quality? Have you ever noticed that a microphone hears threedimensionally?

The best way to appreciate a microphones spatial perception is to listen with both ears and hear all the sound around you or plug up an ear and direct it towards somebody talkin at you, then spin away from them and check out whats missing and where: up, down, front, back, left, right. Youve just experienced the difference between an omnidirectional design (in SENSURAMA) and a directional or cardioid design (different degrees of sensitivity, rejection and isolation depending on where you point your ear). However, the more sonic information you reject, the more you color the sound—which is the ultimate battle and compromise in the design of any microphone.

The way a microphone hears on the three-dimensional plane is by polar patterns (I flunked geometry, too, so dont feel intimidated), and the more uniform they are in each direction the better, because: the sound you finally hear is the sum total of what the microphone perceives in the 360 degrees of space that surround you (which means all that loud, reverberant noise coming from the amps and monitors to the front, back and sides of long-suffering vocalists). The term unidirectional is a misnomer," Greg Hockman of Electro-Voice points out. Theres no such thing as a unidirectional mic—theres always some off-axis response. If I could design something that picked up sound only at 45 degress off the centerline; from the zero axis out front and absolutely nothing past that point in any direction, then Id have the rock n roll concert business by the balls right now," he chuckles. We would never have a gain before feedback problem again; never have a leakage problem onstage; we could get better recordings and concerts and everything else—as far as isolation, anyway. But, again, none of us have been able to change the laws of physics to make that happen."

Directional mics have different levels of sensitivity and output at 90, 180, 270 and 360 degrees. Do you understand now where that bilious sonic refuse youve been hearing is coming from? Obviously the flatter, the more uncolored this leakage is, the better the overall sound. Some of the polar patterns youre likely to encounter are figure 8 (sensitive from front-to-back), 0-180 degrees, hyper-cardioid (greater front-toback sensitivity, with less sensitivity from side-to-side, 90-270 degrees) and supercardioid (lower front-to-back sensitivity, more side-to-side from 90-270 degrees). Therefore, an omnidirectional mic is equally sensitive from all sides.

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Its an awkward concept for a neophyte to visualize," Geoff Langdon concedes, going on to point out that many cheaper cardioids tend to go unidirectional in the highs and omni-directional in the lows. Thoroughly confused, now?

Dont panic, hang in there. Heres a more digestible tidbit to illustrate the difference between the response of an omnidirectional and a cardioid/directional mic. An omnidirectionals response is essentially flat, while a characteristic of cardioids is something called proximity effect. Put your finger back in you ear again (wash them while youre at it) and walk back and forth towards your friends voice: the closer you get, the more the bass frequencies are erm phasized, the farther away you move the greater the preponderance of highs. This is why when you see a vocalist passing the mic back and forth across their face theyre not looking for a warm water route to India. Theyre manipulating the microphone to take advantage of the warm color changes and presence boost inherent in proximity effect—and manufacturers spend a lot of time tailoring the overall response of their mics to accommodate various tastes and vocal characteristics.

It all depends on where your voice needs help. Or if it needs help at all, in which case youd want a mic that tailors out the proximity effect, as Electro-Voice did with their variable D design. Or, as Mike Pettersen points out: The Shure SM58 has a lot of proximity effect—a lot of punch. When Elvis Presley worked that mic hed practically swallow it, and he had a deep, powerful voice, so it got muddy. Now you couldnt tell the star to change his style, so they switched him to an SM54 which is directional but has no proximity effect. The mic better complemented his technique."

So for buyers of hand-held cardioid vocal mics (by far, the most popular models), you need to consider whether you want to sing into the mic or around it; if your voice is powerful like a Pat Benatar or frail and delicate like Stevie Nicks; if you want to sound like yourself or better (be honest now); do you sing from the chest, throat, nose or all three like Americas premier howler, Steve Perry of Journey (...calling all cars...calling all cars").

Steve Perry has a very interesting technique," Greg Hockman observes, in commenting on Electro-Voices Fast Fourier Transfer Analysis of his voice—part of their attempt to define Perrys subjective quality in terms of objective measurements. In working on custom mics for Steve we found that the range of his fundamental fell between 85Hz and 500Hz. Its a fairly limited range, but hes a very accurate, creative singer and to get higher notes hell shift his voice from chest to throat to face, and hell produce these 2nd and 3rd order harmonics that are so strong they can drive a microphone element into clipping. We studied the effect of pinching his nose to observe the variation in frequency from throat voice to sinus voice, and it made a significant difference." For sure.

Now that you have a handle on omnidirectional vs. cardioid, lets return briefly to the characteristics of dynamic, condenser and ribbon principles. Mike Pettersen summarizes:

Dynamic (BALLS) —You have a diaphragm made out of mylar. Glued to that is a thin wire suspended in between magnets. The diaphragm responds to changes in air pressure, and the coil wire moves in the magnetic field, which produces a corresponding variation in current." Condenser (DETAIL)—Has a diaphragm, but instead of a coil wire you have a very thin coating of gold, because its a good conductor; a little air space, and behind that a back plate, which has a permanent charge of electricity. The air space holds a certain amount of electricity; and acoustical movement pushes the diaphragm back and forth across the air space and the backplate—like squeezing a malleable plastic bottle filled with water and watching the fluid rush back and forth —thus varying the charge which produces a signal. The advantage of a condensers lighter diaphragm is that it responds quicker and easier to subtle sounds and high notes like cymbals, acoustic guitars, flutes and grand pianos—more open and transparent. The trade-offs are it has less SPL capacity than a dynamic, and because of the permanent electric charge, you need a built-in amp, which has to be internally powered with a battery (electret condenser) or a phantom power supply."

Ribbon (MELLOW)—Is a variation on a dynamic, with a very thin piece of aluminum ribbon suspended in a magnetic field. Essentially the ribbon is both the diaphragm and the coil—its the part that moves, and its the part that the electricity moves through. It responds well to lower and midband frequencies, and, particularly for vocals, it imparts a lot of warmth—it takes the shrillness out. As it doesnt respond so well to the highs, you can use it for pleasant attenuation effects, or to complement sound sources without the high frequency content, like french horn or flugelhorn. But ribbons tend to be fairly fragile, cant take the transients the way a dynamic can and are generally used in recording applications. Beyers are the first really roadworthy ribbon." Jeff Levy adds that The rule of thumb is if you wouldn't put your ear right next to it, dont put a ribbon there. You wouldnt put your head inside a bass drum, would you?"

Pretty complex ideas, huh? Nah. Theres a lot more to it than we have room to cover here (look for future articles to flesh out the ideas), but as you can see (and hear, hopefully), a lot of it comes down to common sense—understanding the nature of your sound source, and how a particular microphone will best respond. After all, a microphone is a musical instrument, too, not simply a convenient phallic member to gesticulate suggestively during lulls in the action or to flail around like John Henrys hammer. Listen to your microphones and theyll listen to you.