M-Audio Microphone User Manual

Contents

Microphone Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3

Microphone Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3

Capsule Size . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4

The Backplate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5

Patterns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6

Top Address vs. Side Address Designs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8

Microphone Electronics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8

Manufacturing Standards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10

Caring for Microphones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13

Shock Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13

Pop Filters and Windscreens . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13

Temperature and Humidity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13

Cleaning and Storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14

Basic Miking Concepts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15

Close-Miking vs. Distance-Miking Techniques . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15

Large Capsules vs. Medium Capsules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16

Dealing with Unwanted Low-Frequencies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16

The Mic Preamp . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16

The Recording Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17

Phasing Issues with Multiple Microphones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18

Stereo Miking Techniques . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21

X-Y . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21

Blumlein . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22

ORTF . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22

Mid-Side . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22

Spaced Omni . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23

Decca Tree . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23

Specific Miking Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25

Vocals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25

Acoustic Guitar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26

Electric Guitar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27

Grand Piano . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27

Drums . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28

The M-Audio Family of Microphones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

oubleshooting

Contact Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35

Tips

Chapter 1

output signal

voltage

coil

fixed magnet

diaphragm

output signal

voltage

coil

fixed magnet

metal ribbon diaphragm

fixed magnet

output signal voltage

diaphragm

Choosing & Using Microphones

Microphone Design

While all micr

ophones are designed for the common purpose of converting variations in sound pressure to electronic signals, different technologies have their benefits depending upon the a

pplication.This chapter examines the merits of different design types, capsule sizes, polar patterns,

electronics and more.

Microphone Types

The three main types of microphones in common use today are dynamic, ribbon and condenser. Each has unique attributes appropriate for different applications.

Dynamic microphones

The dynamic or moving-coil microphone is the easiest to understand. It is the classic technology taught in grade school as the inverse of the common speaker. A plastic or metal diaphragm is attached to a copper coil that is, in turn, suspended in a magnetic field.Sound pressure waves hitting the diaphragm cause it to move, and with it, the coil within the magnetic field. The resulting magnetic fluctuations translate to electrical fluctuations generally corresponding to the physical fluctuations of the original sound wave.

Due to the requirement of attaching the coil directly to the diaphragm, dynamic diaphragms are thicker and, therefore, less sensitive than the ribbon and condenser microphones discussed shortly.These same design considerations also give the ability to take the greatest amount of sound pressure before distorting, as well as the greatest amount of physical abuse. Dynamics are also the easiest and least expensive to make. Dynamics also to tend to color the sound in the range of about 5k to 10k, and start to sound thinner when more than about a foot away from the source.

In dynamic mics, sound pressure moving the

diaphragm causes the attached voice coil to interact

with a magnetic field to produce an electric signal

For these reasons, dynamic mics are most often found in the average stage situation. After all, live performance environments are much more likely to subject mics to torture such as high volume, sweat, the elements, shock and being dropped. In the studio, dynamic mics are most often used to close-mic drums due to the possibility of wayward drum sticks. Large-diaphragm dynamics are often used on kick drums due to high sound pressure levels and low-frequency content.

Ribbon microphones

Ribbon mics are another form of dynamic microphone distinct from the moving-coil variety. A very thin metal ribbon suspended between the poles of a powerful magnet moves in response to sound waves, thus cutting through the magnetic field and inducing a flow of electrons. The resulting low-voltage output is typically fed to a step-up transformer and sent down the mic cable. The extreme thinness of the ribbon makes this type of mic the most sensitive, especially at very low sound levels.They are most often used in close-miking situations and, because they are also the most fragile and costly mic design, ribbons are typically reserved for very controlled conditions.

Like moving-coil dynamics, ribbon mics color the sound in a way that is often employed to warm up brassy sounds. (Ribbons are a great choice for recording sax, for example.) They also tend to

In ribbon mics, sound waves cause a thin metal

ribbon to mov

e within a magnetic field to produce

a current

have very low output, thereby requiring more electronic gaina factor that necessitates

small capsule

medium capsule

large capsule

20 20k10k 15k1k

20 20k10k 15k

20 20k10k 15k1k

ultra -thin diaphragm

solid backplate

capacitance

output signal

Choosing & Using Microphones

high

-quality preamp electronics in order to avoid noise.

Condenser microphones

Condenser mics are the most common for studio use. A thin electrically conductive diaphragm is suspended over a back plate, forming a delicate flexible capacitor.When sound waves excite the diaphragm, the distance between the diaphragm and back plate changesand with it the capacitance. This capacitance change, in turn, produces a voltage change. Associated circuitry converts these variations in voltage to a signal that is sent to the preamp. The power required by this design is serviced by the 48-volt phantom power commonly found on preamps and mixer inputs.

The diaphragms of condenser microphones are made of extremely thin metal or metalized plastic similar in thickness to kitchen plastic wrap.Their thinness makes condenser mics very accurate in frequency response and extremely sensitive to transients, such as the initial crack of a drum being struck. In addition to imparting the least sonic coloration of any microphone design, the sensitivity of condensers extends much further from the source than other mics, thus allowing greater flexibility.This greater sensitivity also provides the engineer with the option of picking up more the room ambiencea factor that can add a great deal of realism to a recording.

Condensers are more delicate than moving-coil dynamics, yet much more resilient than ribbons. Due to sensitivity to low-frequency handling noise and the delicacy of the diaphragm, condensers are invariably used in conjunction with a shock mount, and often with the addition of a pop filter. The sonic characteristics of condensers and the need for TLC make them more ideally suited for studio recording. That is not to say that condensers cant be used for so me tas ks on stage just that the environment should be controlled, such as in a professional show where cables are secured, mics are shock-mounted against vibration, and the stage is restricted to professional personnel.

In condenser mics, sound waves hitting the diaphragm change the capacitance

in the field between the charged

diaphragm and backplate

Since condenser construction technology is much more labor-intensive and sophisticated compared to that of dynamics, good quality condensers tend to cost comparatively more money. Condensers are excellent choices for miking vocals, acoustic guitar, piano, orchestral instruments, saxophone, percussion and sound effects.As condensers are the predominant type of microphone for studio use, this guide will focus on condenser applications.

Capsule Size

The capsule incorporates the all-important diaphragm assembly that translates sound pressure into an electric signal. Condenser capsules come in three basi c sizes small, medium and large. Generally speaking, frequency response is a function of diaphragm size. Consider what happens with speakers of different size. As woofers get larger, they become more efficient at producing low frequencies and less efficient at producing high frequencies. In general, the same is true as the diameters of diaphragms

ease (with some ca

incr

Signal-to-noise ratio of the micr more surface area that a diaphragm has, the greater its potential sensitivity to sound pressure and

onger the output signal.

the str signa-to-noise ratios than do small ones.

veats well cover in a minute).

ophone as a whole generall

large dia

esult,

As a r

Without intervention, microphones tend to be

less linear as the diaphragm size increases

es in par

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phragms inher

t to diaphragm size.The

y exhibit m

entl

uch better

Small Capsules

patented Disk Resonator boosts

high frequencies for full

frequency response

backplate

sound waves

3-micron evaporated gold

diaphragm

Choosing & Using Microphones

Small capsules ar

e typically those with diaphragm diameters of less than about 1/2. Categorically, they are extremely accurate through the audible range of 20Hz to 20kHz. Their poor signal-tonoise ratio

, however, requires tricks with electronics and relegates small capsules to being most

useful for measurement rather than recording.

Medium Capsules

Medium capsules have diaphragms that are approximately 1/2 inch to 3/4 inch in diameter. Given the right design and manufacturing, they typically exhibit flat frequency response from about 20 to 18k. Their diaphragms are also large enough to deliver signal-to-noise ratios acceptable for professional use.

Large Capsules

Large capsules have diaphragms measuring 3/4 inch to one inch or even greater. Since larger diaphragms yield better signal-to-noise ratios and greater sensitivity without having to induce additional gain stages, bigger is typically considered better. Large capsules also tend to produce greater low frequency detaila quality that cant be measured so much as heard. Large capsules exhibit a proximity effect (most predominantly in the cardioid polar pattern), meaning that they tend to sound more boomy as they get closer to the source. Large diaphragm M-Audio mics include the Solaris, Luna and Nova.

The Diaphragm

The diaphragm is a critical component because it is responsible for responding directly to sound waves. The sensitivity of a mic is partially related to the thinness of its diaphragm. (Recall that the comparatively thin diaphragm of a condenser is largely what makes this type of mic much more linear and sensitive to detail than a dynamic moving-coil mic.)

Originally, condenser diaphragms were made from very thin, light metal such as nickel. As technology evolved, it became possible to use synthetic materials such as mylar in order to create tissue-thin membranes. Since condenser diaphragms need to conduct electricity, these synthetic materials have a thin layer of gold applied to themthe thinner, the better. Most modern condenser diaphragms are 6 to 12 microns in thickness. (A human hair is 40 microns in diameter.) The M-Audio large capsule mic, the Solaris, employs a special ultra-thin 3-micron, highly resilient mylar diaphragm. This delivers a degree of sensitivity unparalleled in the industry. (Physics dictates that we employ 6-micron diaphragms in our Luna and Nova models.)

In the old days, manufacturers would apply the gold to the diaphragm using a process known as sputtering.They would place the diaphragm substrate in a vacuum jar, atomize the gold, and then blow the gold onto one side of the material.Todays vacuum chambers are far superior, allowing us to use a refined technique where we place our ultra-thin mylar film in a complete vacuum and evaporate the gold in such a way that it adheres uniformly to the mylar.The result is a diaphragm that is we feel is the most sensitive in the industry.

Condenser diaphragms can be extremely sensitive to humidity and temperature changes. In order to minimize that, we temper our diaphragms by baking them for specific times at specific temperatures in order to insure maximum stability and performance.

The Backplate

In a condenser mic, the diaphragm is suspended over a backplate that carries one half of the electrical charge that r microphones were made of solid brass.In an effort to cut costs, most modern manufacturers make the backplate out of injection-molded plastic and metalize them in some wa

esults in the ca

pacitance

The backplates of the best classic condenser

Critical listeners

invariably prefer the sound of solid brass. Needless to say,

screw/contact

resonator disk

disk spacer

backplate screws

diaphragm

w/ mounting ring

ring spacer

center spacer

backplate

registration pins

backplate spacer

backplate base

Choosing & Using Microphones

30 cm (1')

7.5 cm (3")

0.6 cm (1/4")

-5

--10

50 100 200 500 1k 2k 5k 10k

Frequency (Hz)

Relative level (dB)

e use solid brass backplates in all M-Audio mics.

The spacing betw

een the diaphragm and backplate is critical. In order to avoid problems with barometric pressure, the spacer ring has a break in order to allow air to move freely between these two components. We precision drill approximately 100 extremely fine holes in the backplate, some going all the way through and some only going partially through. This combination further allows the appropriate amount of damping for the diaphragm.We then lap the surface in order to ensure that it is completely flat.This operation requires such precision that we measure the results not with a ruler, but with reflected light.

This level of precision is only possible due to modern computer-controlled manufacturing techniques. The important distinction is that these operations are

The major components of a large M-Audio condenser

capsule are a solid brass backplate and an ultra-thin

evaporated gold diaphragm

programmed and supervised by human technicians at every step. All-in-all, there are several hundred precision operations that go into making each of our solid-brass capsules.Thats more than the number involved the crafting of the average Martin gu ita ran d were talking about something the size of a 50-cent piece.

Patterns

The term polar pattern is used to describe the response of a microphone to sound sources from various directions. Each type of polar pattern has its own place and usage in the recording process. Note that the classic polar pattern definitions apply most accurately when sounds hit the microphone on axisthat is to say, approaching perpendicular to the planar surface of the diaphragm. In general, microphones tend to become more directional in focus as frequencies increase. Put another way, capsules are generally less sensitive to high frequencies off axis. This phenomenon is typically less significant in medium capsules than in large capsules.

Cardioid pattern

The cardioid is the most common polar pattern found in microphones. The name derives from this patterns resemblance to a heart shape. Cardioids are unidirectional, meaning that they pick up sound primarily from the front of the capsule. The back of the capsule rejects sound, allowing the engineer to isolate the signal source from other performance elements or background noise. More noticeable in larger capsule designs, cardioid patterns typically exhibit a

proximity effecta boost in low-mid

frequencies as the proximity between the source and mic increases. Proximity effect is also more prominent with both larger capsules and lower frequencies.

Omni pattern

As the name implies, the omni-directional, or omni pattern, picks up sounds equall used to ca thereby yielding a more open sound compared to the more

ocused quality of car

f Foley sound effects, and realistic acoustic instruments assuming that acoustic space of the r is desirable.

pture room resonance along with the source,

dioid.

y w

ell fr

om all dir

ections.

Omni is great for vocal groups,

ding en

ecor

Omni is

onment

vir

The proximity effect causes increased output in

the low-mids as distances between the mic and

Cardoid patterns are most

sensitive on the side of

the capsule

source increase

Omni patterns are

sensitive to sound from all

directions

Omni also exhibits significantly less proximity effect than cardioids. One result is that omnis are

Choosing & Using Microphones

30dB

20dB

10dB

0dB

10dB

0dB

330

300

270

240

210

180

150

100 Hz 1 kHz 10 kHz

some

what less sensitive to the movements of an animated vocalist. Another is that omnis tend to have less need for EQ. As mentioned earlier,while omnis pick up 360 degrees of sound, they tend to be mor

e directional as frequencies increase espec ially in larger capsules.

Figure 8 or bidirectional pattern

The figure 8 or bidirectional pattern is equally sensitive on the two opposing faces of the microphone, yet rejects sound from the sides.This pattern does exhibit the proximity effect found in cardioid patterns.

The figure 8 is excellent for capturing a duet or face-to-face interviews with a single mic. The —40dB side rejection spec also makes it great for isolating an instrument like a snare from the rest of the drum kit.Figure 8 is also one of the key components of M/S (mid-side) mikingan advanced stereo recording technique well look at little later.

Super-cardioid pattern

The super-cardioid pattern exhibits an even narrower area of sensitivity than the classic cardioid and is used for very sonically focused recording. Super-cardioid is great for zeroing in on that perfect sweet spot for instruments such as piano or drum.This pattern is also ideal for live recording sessions where isolation is important, including minimizing bleed between a vocalist and their own instrument.

Single pattern vs. multi-pattern mics

The most inexpensive way to make a microphone is with a single fixed pattern. Cardioids have openings in the backs of the capsules that produce the physics of a unidirectional pattern.This is an inherently fixed pattern design.An omnidirectional pickup pattern can be achieved by sealing the back of the capsule, resulting in another fixed pattern. Super-cardioids employ yet a different design. In most cases, different back-end electronics are required for each pattern, thus making it difficult to make interchangeable capsules.

The secret to building a single mic with multiple pickup patterns is placing two cardioids back-to-back in combination with various electronic tricks. An omnidirectional pattern occurs as the result of wiring two backto-back cardioids in phase with each other. Similarly, those same two opposing cardioids wired out of phase yield a figure 8 or bi-directional pattern*. Tweaks to the polarity and output level result in a super-cardioid pattern. While the presence of two high-quality diaphragm/backplate assemblies incr

eases the cost, this solution provides the best polar pattern performance and is still significantly less expensive than buying multiple microphones in order to have a choice of patterns at your disposal.

Figure 8 patterns are

sensitive on opposing sides

and exhibit strong rejection

at 90 degr

ees off axis

In multi-pattern microphones, two cardioids combine

in different ways to create other patterns

All microphones are less sensitive to high

frequencies off axis (omni example shown)

The super-cardioid

pattern has an even

greater focus of sensitivity

than cardioid

This approach to capsule design can be seen in the M-Audio Solaris. The Solaris employs an opposing pair of the same diaphragm/backplate assemblies, thus allowing for the selection of

ultiple patterns via s

*Tip: uninitiated. One side will sound strange to a vocalist or speaker who is simultaneously monitoring the mic

witches on the body of the mics.

Note that the out-of-phase wir

ing of the two sides of a f

e 8 capsule can play tr

igur

icks on the

signal through headphones.That’s because one side of the mic is in phase with the performer (and therefore

top address

side address

Choosing & Using Microphones

reinforcing their perception of their own sound) while the other side is not. Addressing the in-phase side while monitoring produces optimal monitoring results.

Top Address vs. Side Address Designs

The orientation of the diaphragm within the head of the microphone determines if the microphone is addressed from the top or the side. While not an absolute rule, medium diaphragms are typically top-address while large diaphragms are usually side-address. As you might surmise from the previous discussion about design considerations in attaining various polar patterns, top-address mics typically have single pattern (at least without physically changing the capsule) while sideaddress mics lend themselves to the possibility of back-toback capsules for switchable patterns. Note that on side-

Side addr

ess and top address

microphone designs

address mics, the side with the logo is usually the primary or cardioid side.

Polar patterns aside, the practicality of side-address versus top-address designs also has to do with logistics. Top-address microphones can usually fit into tighter spots than can side-address mics (between drums, for example).This is yet another reason why pro engineers keep a variety of mics in their arsenal.

Microphone Electronics

As weve seen, the microphone capsule is responsible for translating sound waves into electrical signals. The other important part of the microphone is the head amp that conditions the sound coming from the capsule so that it can be transmitted through a length of cable to an external preamp or console.

Part of a head amps job is impedance conversion. (See A Word About Impedance for more information on impedance.) The average line-matching transformer found in dynamic or ribbon microphones has to convert on the order of several thousand ohms down to around 200 ohms (or from half an ohm up to about 200 ohms).The condenser microphone presents a challenge of a different magnitudeconverting a signal in the range of two billion ohms down to 200 ohms.This incredible leap is beyond the scope of most output transformers, requiring the addition of a specialized amplifier.

Impedance essentially describes the resistance in a circuit.Water flowing through a pipe is a good analogy to electrons flowing through a wire. Lets say youve got a pump designed to put 100 pounds of pressure into an eight-inch pipe. If you double the size of the pipe to 16 inches, you get half the pressure.While the pressure is now only 50 lbs,there is no damage to the system. Halving the size of the pipe, on the other hand,yields twice the pressure that the system was designed for. As a result, back-pressure affects the pump, further reducing its efficiency and increasing the potential of an explosion.

In terms of audio electronics, the pipe scenario is analagous to inputting the output from a 100-watt amp into 8-ohm

While using 16

ers.

speak almost certainly blow up the amp.Thats why guitar amps designed to run into different speaker ratings often have output transformers with 4-, 8- and 16-ohm taps which appropriately condition the output signal.

Guitar pickups and most dynamic mics are considered to be high impedance, meaning that they exhibit an impedance of many thousands of ohms. Low-impedance signals are generally around 200 ohms or less.While the high-impedance signals typically exhibit greater voltage, they can only be run through about 20 feet of cable before they begin to lose high frequencies (or require additonal amplification in order not to). Low-impedance signals can

y be run m

typicall

uch fur

A Word About Impedance

ohm speak

ers is safe (though it reduces output power), switching to 4-ohm speakers will

ther without detriment.

An output transformer and/or amplifier serves as a sort of translator and, in audio, we expect that

Choosing & Using Microphones

translation to be excellent in or signal-to-noise ratio. Just as a professional language translator costs more than someone who just took a f

ew years of foreign language in high-school, pro-quality output transformers and amplifiers cost more than garden-variety ones. (A single transformer like those used in each channel of pro consoles and outboard preamps can cost more than a complete inexpensive multi-channel mixer.) Because the quality of this formidable translation is so critical in a professional-quality microphone, all M-Audio mics employ high-quality Class A electronics in the head amp.

Tubes vs. solid state

The head amp can employ either tube electronics or less expensive solid state electronics. Before we can effectively compare these two technologies, it is important to understand some fundamental concepts.There are three main ways to measure how accurately an electronic circuit passes soundfrequency response, total harmonic distortion (THD), and dynamic distortion. Frequency response is the simplest to understand.Were simply talking about whether any highs or lows are rolled off, or if any frequencies are cut or boosted to exhibit a non-linear frequency response. Both tube and solid state electronics can be made without significant deficiencies in frequency response.

Regarding THD,all electronics induce some kind of harmonic distortion, i.e. harmonics that are not present in the original source. The nature of the harmonic distortion has more to do with the associated circuitry than with tubes versus solid state. components handle the entire signal waveform) tends to produce lower-order harmonics. On the other hand, separate devices) tend to produce higher-order harmonics. For this reason, Class A strikes most people as sounding warmer. (All M-Audio mics employ Class A circuitry.)

That brings us to the third, more mysterious element called dynamic distortionsomething that the industry didnt even have the technology to measure until quite recently. Dynamic distortion refers to the accuracy or transparency over time,particularly critical regarding the transient at the very beginning of a sound.Take the recording of a finger snap,for example.You can roll off the highs and lows and/or introduce a good amount of distortion, yet still perceive the sound as a snapping finger. Change the dynamic, however, and that snap can quickly lose its characteristic snap. In general, accuracy in reproducing dynamics can make the difference between something sounding full and three-dimensional or flat and two-dimensional.

Class B (where the positive and negative parts of the waveform are amplified by two

der to maintain frequency response, dynamic range, and

Class A circuitry (where all amplifying

Ironically, the discussion comes down to measuring things that dont matter and not measuring things that do.Tubes measure greater in THD than solid state.While one can measure the difference between .01 percent THD and .001 percent THD, its practically impossible to hear that difference. On the other hand, while its difficult to measure dynamic distortion you can definitely hear it. Solid state electronics exhibit many orders of magnitude more dynamic distortion than tubes.This is a major reason why tube mics make recordings sound truer to life.

Tube electronics

Tubes cost more money to manufacture than comparable solid state electronic components. In fact,the music industry is one of the few places where tubes have value in the face of more modern electronics.

Its a known fact that the average tube exhibits more inherent noise than solid state electronics. In general, the smaller the tube, the better. Larger tubes have a greater propensity for being microphonic, i.e. generating noise from mechanical movement of the internal parts. They also use higher voltages that result in more heatand subsequently more noise. Most manufacturers tube mics employ larger 12-volt tubes like the 12AX7an older tube design that is noisier when used in microphone design.

TIP: One of the first things to be aware of is that not all products advertised as being tube mics employ tubes in the main signal path. a tube in the side-chain. (You can literally cut the tube out of the circuit on some models and the mic will

Some popular lo

w-cost mics utiliz

e less expensive solid-state circuitr

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still work.) The theory there is that the tube is used as a sort of processor to “warm” up the sound.The

Choosing & Using Microphones

reality is that these are still solid state mics masquerading as tube mics as cheaply as possible.

Because of the ph

ysics behind tube operation, tube mics have classically been subject to certain physical restriction on the length of the cable between the microphone and power supply. As a result, tube mics are normally restricted to cable lengths of about 15 feet. This has sometimes required the use of solid state mics in scenarios such as drum overheads, remote recording or orchestral recording.

Solid state electronics

Solid state microphones cost significantly less to manufacture than tube mics. As such, they are found in the less expensive condenser mics on the market. (As stated earlier, some manufacturers put low-quality tubes in their solid state mics like an effects circuit in order to advertise products as being tube mics.)

In most solid state condensers, the key components are a series of op amps. All M-Audio mics employ FETs (field effect transistors) instead. Logic says that op amps should be preferable because they have lower measured amounts of THD. As discussed previously, while that difference in THD specs is measurable it is not audible in well-executed microphone applications. Op amps, however, can have much more dynamic distortion than FETssomething you can hear. Moreover, many designs use multiple op amps to do the job of one FET. The difference is so profound that many people think that our solid state mics sound like most manufacturers tube mics.

The Myth of Tube Warmth

There is a common myth that tubes are warmer sounding. It certainly can be said that cranking up a tube amp will make an electric guitar sound warm, fat or distorted. That scenario, however, is one in which distortion is desirable. On the other hand, distortion is the enemy of the engineer who is attempting to record a sound source faithfully and realistically. Here, you want accuracy and transparency rather than any coloration that might be described subjectively with a word like warmth. Fortunately, there are many types of tubes and related circuitry that result in comparatively transparent sound.

It has also been said that tubes warm up digital recordings.This implies that there is something inherently deficient in digital recording.While some purists will always make a case for analog over digital, the fact is that a vast number of todays pro recordings are made with digital technology such as M-Audios 24-bit/96k Delta cards, USB and FireWire solutions.

Digital recording significantly increased the dynamic range, allowing us to better hear the dynamics of recorded material. As a result, people were quick to label digital recording as cold, when using solid state mics. When using a tube mic, everything suddenly sounded warmer by comparison. In actuality, digital recording simply gave us the means of hearing differences we didnt hear before (such as how tube

output is dynamically truer than solid state).

Manufacturing Standards

e are quite a number of condenser microphones to choose from on the market today. Many

Ther look pr is that most companies engineer for profit.This guide was designed to help you think about whats inside those shin

The story behind affordable matched pairs for stereo-miking

One of the factors that make a significant difference between amateur and professional recordings is the use of stereo miking techniques. Pro engineers have long relied on matched pairs of microphones to attain optimal results from stereo recording methods. Why a matched pair? You wouldnt consider monitoring with a mismatched pair of speakers, right? Similarly, you want the left and right mics hearing exactly the same way in order to achieve a balanced sound.

essional on the outside and, indeed, most will give you acceptable sound. However,the fact

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From a technical perspective, the two mics need to be as identical as possible in frequency

Choosing & Using Microphones

esponse. A flat frequency response implies that there is no deviation in the output level versus the input level at any and all frequencies across the audible spectrum. While a flat frequency r

esponse is theoretically ideal, it is rarely achieved completely in any audio component. For example, a mic might exhibit a 1dB boost at 1kHz and start rolling off 3dB per octave at 14kHz.A perfectly matched pair would exhibit the same exact characteristics in both mics. Here again, such an exacting match is rare.Therefore manufacturers each establish their own window of acceptable deviation that they will certify as a being a matc hed p air there is no industry standard. (Please note that we are actually talking about two different variables that are subject to interpretation and little disclosurethe d eviation between two matched microphones of the same model, as well as their deviation from the given manufacturers standard reference mic for that model.)

Even the most famous of classic microphones have exhibited disparities in frequency response of 6dB of more from unit to unit. In such circumstances, manufacturers must search through a batch of mics to select a pair that is relatively close in responseon the order of 2dB up or down for a total window of about 4dB. It is often necessary to place a special order (and pay surcharge as large as 20 percent of normal cost) for such matched pairs. This is not the case with M-Audio microphones. In order to pass inspection, all mics in our line must be within +/-1dB of not only each other, but of our  golden reference mic for that modelthe one we wont sell for any price.

Higher standards

M-Audio is able to offer incredibly high quality and tight tolerances at affordable prices for several reasons.The first is that highly skilled technicians use the latest computer-controlled equipment for manufacturing and testing.

The reality of todays marketplace is that most companies manufacture their products offshore in order to be profitable. Many microphones on the market today are made in China or other countries where labor is less expensive  even the ones that say that they are made elsewhere. At M-Audio, manufacturing is a hybrid operation. The designs all start in the USA, as do the manufacturing of all critical path elements like transformers, capacitors, resistors and diaphragm material.We then complete the machining and assembly in our own facility in Shanghai. In this way we attain the best of both worldsquality and affordable pricing.

While were on the subject of standards, lets talk about the frequency response graphs that are often included with microphones.These graphs illustrate the deviation between input and output across the frequency spectrum. The ideal is to have as flat a line as possible indicating as little deviation as possible. Such graphs can be misleading because the industry has no universally accepted measurement standards that factor in distance from the mic, volume, angle relative to axes, and so forth. Moreover, there is no standard for rendering these graphs. Major deviations apparent on a graph calibrated vertically at +/-10dB look much more like a flat line if displayed on a graph calibrated at +/-100dB. So in a world where everybody draws nice looking graphs because they feel they must in order to be competitive, we simply decline to play the game until such time that standards exist that level the playing field. As stated earlier, all M-Audio mics are manufactured to within +/-1dB of each other and our golden reference standard.Were confident that your ears will tell you everything else you need to know.

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