How to Use Microphones for Location Recording

OK, you have chosen your recording medium, Digital Audio Tape, a laptop computer, a portable flash-memory recorder such as a Zoom H2 or H4n, or perhaps a DSD format Korg MR-1 or MR-1000. You have picked a suitable mixer or microphone preamps, and have bought yourself a few good microphones. Nice. Unfortunately, all of this fine equipment will do you little good unless you know how to use it. This week, we're going to look at how to use microphones to best advantage in a location recording situation. 

The Type of Music Dictates the Procedure

The first thing that has to be considered and understood is the fact that even though we humans tend to look upon microphones as surrogate ears, they really aren't. Our ears don't just pick-up sounds, they, with the help of our brains, both process and interpret sounds. We have the ability to isolate sounds from the background. That's why we can still listen to music in a noisy nightspot. We can pinpoint instruments in space, we can do any number of signal-processing functions without even thinking about it consciously. Still and all, we are applying intelligent signal processing to the sounds that our ears pick up. Microphones cannot do this. All microphones can do is pick-up, and convert to an electric current, whatever sounds occur within the space that the microphones occupy. This sound field is modified only by the characteristics of the microphone itself; it's frequency response, it's pick-up (or polar response) pattern, it's noise-floor characteristics and it's maximum sound-pressure level. That's it. Microphones make no "decisions" about what to highlight, what to suppress, or even what to include in it's pick-up. All of these decisions have to be made by you, the recording engineer, and they have to be made before the music starts. These decisions are a result of knowledge and experience. Here, I can start you down the correct path with some of the more universally applicable knowledge, and the experience, you'll soon pick-up for yourself by experimenting with the principles found here. 

The second thing to consider is that because of the above facts about microphones, different kinds of music require slightly different procedures to obtain the best results. Since the recordings that you are likely to make will be recorded in concert before live audiences, studio techniques usually do not apply. While classical music can benefit from a number different microphone arrangements and can give satisfying results from may different perspectives from relatively close-up, to fairly far back in the hall, jazz and pop music needs to be recorded close-up. Distant prospectives only tend to obscure the intricate play of instruments in jazz, and tend to make pop musicians seem far away. 

What We Want is Stereo

In the 1960's when multitrack tape recorders became widely available, a technique for recording that utilized 8, 16, 32, 48, 64, or even 96 tracks(!) gained popularity with many of the major record companies. This practice came from the world of rock-and-roll recording with their over-dubbs, sound-on-sound, sound-with-sound and other special effects. It was found that recording each individual instrument and voice to a separate, isolated track allowed for the flexibility to double-up on voices and instruments and add effects in post-production. This was a good move for pop music and can be heard to best advantage in the early works of guitar and recording technology legend Les Paul (with his then wife, Mary Ford). Listen to Ford perform a duet with herself on "How High the Moon" Rock innovators , The Beach Boys, used these techniques to great effect in their famous "Good Vibrations". But, as great as these multichannel techniques were for gimmicky pop and rock music, they were translated to classical and jazz recording for an entirely different reason and with very mixed, and often disastrous results. 

It was in the economic atmosphere of the late 1960's and the inflationary '70's where the idea of applying, to classical and jazz, studio multitrack techniques designed for pop music. Recording engineers like Bob Fine (Mercury) and Lewis Leyton (RCA Victor) used minimalist microphone techniques to capture classical performances so stupendously good that they are still revered by audiophiles to this day. In the jazz world, Rudy Van Gelder started recording the L.A. jazz scene with just a "portable" (that meant, in those days, that it had a luggage handle on it) tape recorder and single condenser mike. When he adopted  stereo, he still used only two or three microphones. His recordings, too are highly regarded, even today. But in order to record this way, it takes lot a work to set up the microphones to get the perspective just right. All the while, the players are there waiting for the engineers to make minute adjustments to their microphone placement. Somebody decided that this was expensive. Apparently, it  was much cheaper to set up empty chairs for the "eventual" musicians and place a microphone in front of each one. One microphone is erected for each instrument (and in some cases, for each group of instruments) and then when that is completed, you  called the musicians in, got the performance down on tape in as many tracks as possible and then sent the expensive musicians home. At that point the producer and the mix engineers can play with the balances between the instruments 'till their hearts' content. The result, when mixed down to two tracks, is, unfortunately, not stereo. It's exactly what it seems - multi-track mono. Jazz is almost worse. Each instrument is close miked, committed to its own separate track, and then mixed down to what is called "three-channel" mono. All the instruments are grouped into three groups and sent to either the extreme left, the center (by mixing the instruments equally into both channels), or the extreme right. Again, there is no real stereo image. 

But people hear stereophonically, or as the Greek word stereos denotes, three dimensionally. We not only hear musicians arrayed right to left, we also hear them front to back, and vertically. If the brasses at the back of the band are on risers, and thus higher than the players in front, the human ear can hear that, and in a real stereo recording, that information can be captured. One of the great disappointments of commercial recordings, is that so often, it's not captured. It's so easy to do that one wonders what commercial record companies are thinking. This is where you and I can better them. We, as amateurs,  can make recordings so lifelike as to be literally spellbinding. We want stereo, and this is how we're going to get it...

Real Stereo Recording

To record in real stereo, you theoretically need only two microphones. I say theoretically because this assumes ideal conditions. In less that ideal conditions, you might need more, but a good stereo-pair of microphones is the correct starting point. What is a stereo-pair? Well, basically it is two identical microphones arrayed in one of the classic stereo microphone configurations and placed in front of a group of musicians in such a way as to accurately capture the sound field that surrounds the performance. There are a number of ways to do this, and all can yield excellent results.

Coincident Pair

In the 1930's, both Bell Labs in the US and the BBC in England experimented with stereo sound. Bell Labs' famous experiments concluded that an accurate recreation of the stereo soundfield was possible with just two channels although it was first postulated that this would require many channels. They kept reducing the number of channels employed until only two remained. The soundfield was still stereo and still coherent. Two channels stuck. In England, a man named Alan Blumlein was working for the Columbia Grammophone Co,. Ltd. when he patented his "Blumlein pair" of figure-of-eight ribbon microphones where the mikes were mounted next to one another and and angled away from the center axis at 90 degrees to one another.

Diagram showing Alan Blumlein's co-incident Microphone technique from the early 1930's . His use of ribbon microphones creates a crossed pair of figure-of-eight patterns where the front lobes are in-phase and the rear lobes are out of phase. 

This basic stereo microphone technique is still used and is very viable, giving a sense of space and dimensionality that can make for stunning sound stage presentation. Today, this arrangement is most often referred to as a "coincident pair" and is usually done with cardioid pattern (unidirectional) microphones instead of figure-of-eight bidirectional microphones although the latter can still be used. This arrangement will not work with omni or non directional mikes (unless you want a monaural recording). 

Two small cardioid condenser microphones arrayed as a coincident pair. or modified Blumlien pair. Notice that the faces of the two mikes are set at a 90 degree angle to one another  and the two screens are almost touching. Notice also that the connectors on the mikes appear backwards. IOW, the right channel cable is connected to the mike on the left and vice-versa. This is because, obviously, the left-most mike is facing the right side of the pickup stage and the right-most mike is aimed at the left side of the stage, Playing with the angle from 90 to 120 degrees will widen or narrow the soundstage. 

X-Y Pair

The next stereo arrangement to consider is the X-Y pair. This is similar to the Coincident pair except that the mikes are not in the same plane. They are separated by about 7 inches (the distance between the two mounting points on a standard stereo 'T'-bar mount. Again, the point of departure is 90 degrees between the angle of the two microphone elements, but as in the co-incident pair, varying the angle between the mikes either broadens or narrows the stereo stage. Generally speaking, the X-Y arrangement is better for situations where the microphones must be some distance from the ensemble being recorded. Otherwise, if the mikes are right on top of the performers you're going to get the "spotlight" effect where one mike picks up too much of one instrument and not enough of another, ruining the imaging. If you must be close to the ensemble, or if the ensemble is small, the coincident method is better.  

Here we see the same two small cardioid microphones arrayed as an X-Y pair. This is an acceptable method for miking orchestras, bands, and solo concert grand pianos. Give the mikes a little space to form a coherent image and to pick-up a bit of hall ambience for best results

Middle-Side or MS Miking

M-S miking is hardest stereo microphone technique for most people to understand. It generally consists of two microphones that are coincident with one another (in this case it is imperative that they be arrayed one above the other, or ideally, as a single-point stereo mike such as the aforementioned Avantone CK-40. M-S requires that one of the two mikes (since they are aligned on the same axis vertically, it doesn't matter which) be set to the cardioid (or the omnidirectional) pattern and the other must be set to a figure-of-eight pattern. The cardioid (or omni) mike is aimed forward at the center of the ensemble as if one was making a monaural recording. The second mike is facing 90 degrees from the center of the cardioid mike's pattern. This means that the two lobes of the figure-of-eight are pointing to each side of the sound stage. Obviously one of the figure-of-eight's lobes is in-phase and the other lobe is out of phase. The cardioid or omni middle or 'M' mike is fed into one channel of the microphone mixer and is pan-potted to center, and the figure-of-eight or 'S' mike is split into two feeds and routed to two separate microphone inputs where S+ is pan-potted to the extreme left and S- is pan-potted to the extreme right. S+ is in phase and the S- is 180 degrees out of phase. The level on the cardioid mike is set normally and the two faders on the figure-of-eight mike are brought-up together. Obviously, if the faders on the figure-of-eight mike are closed, one gets pure mono. but as one brings-up the figure-of-eight side mike, the following matrix occurs:

Where M = the Middle or front-firing cardioid or omni mike and 

S+ = the in-phase lobe of the side-firing figure-of-eight microphone

S- = the out-of-phase lobe of the side-firing figure-of-eight microphone and R = right and L= left

L= M + (S+) 

R = M + (S-)

M-S or Middle-Side stereo microphone technique. Here, in the example, the front-firing or 'M' mike is an omnidirectional, but it can be a cardioid as well. Cardioid works best in a concert recording situation because it minimizes audience pick-up. 

The advantages of M-S miking are several. First of all, an M-S miked recording is perfectly phase coherent and therefore mixes to mono (for mono radio, for instance) perfectly, without loss. More importantly (in this day and age) is that it lets the recording engineer control the width of the soundstage from his recording console. The more Side mike that's mixed-in with the M mike, the wider the pick-up. The less Side, the narrower the soundstage, until, with the Side mike killed completely, one gets straight monaural sound. 

Spaced Microphones

The last stereo technique is probably the most obvious: Spaced microphones. This is one of the oldest of the techniques used to make stereo recordings and indeed, the famous Mercury records of the 1950's and 60's as well as the early RCA Red Seal stereo recordings were made this way. Bob Fine of Mercury started recording in the early '50's with a single omnidirectional condenser mike placed in front of the band or orchestra. When stereo came along he added two more omni-directional mikes for a total of three. At first, the center mike was just for mono compatibility (in those days, record companies put out dual inventory. Releases would be available as both stereo and mono titles). Fine would use the center track to cut the mono disk, and the two flanking ones to cut the stereo. At some point, he decided to mix the center mono track equally into both the left and right channels. This gave better center fill on the recordings and if you listen to one of the SACD multichannel releases of some of Fine's three-channel recordings (with a third speaker and amp, preferably identical to the your other two) you would be able to hear how well this works. Most of us can't afford to do that with the price of equipment these days, but I have heard it at an audio dealer and it is impressive. Mostly spaced arrays are done with omni-directional mikes, but it can be done with cardioids. With omni's it is possible to place the mikes farther apart than with cardioids without worrying about a "hole in the middle"effect. Under the best of circumstances, spaced mikes can give a pleasing result, although I've never heard spaced mikes give a pin-point stereo image like the other stereo techniques discussed here. The main reason why they were used in the "golden age of stereo" of the '50's and '60's, and continue to find some favor with record producers, even today, is the fact that omnidirectional microphones tend to have much flatter frequency response and and a lot better low end than do cardioids or figure-of-eight microphones. 

A spaced array pair of Microphones 

Spaced pairs work because instruments located halfway between the two mikes are picked up equally by both and therefore, during playback, locate themselves between the two speakers. The left microphone picks up the sounds from the left side of the ensemble and the right side of the ensemble with equal intensity, but the sound originating on the left, that is to say, closer to the left microphone, is received earlier than the sound originating on the right side of the ensemble (and vice-versa). This is what gives spaced pairs their stereo ability. In coincident and X-Y setups the differences are both in intensity and phase, and this is what gives the stereo effect. In terms of absolute location the human ear responds to phase and intensity differences more than it does to time delay. This makes the coincident methods better at presenting an accurate soundstage. 

Placing Microphones

Placing microphones is somewhat of an art. I know recording engineers who have been doing this for years and they still don't "get it". We're going to assume for sake of this discussion, that the ensemble being recorded is a college band. We are also going to use an X-Y pair of cardioid microphones. 

The first thing we need to do is to see where the band will set-up. Hopefully the chairs will be already arranged or you'll have to wait for the members to arrange them. Then, obviously, you have to find the center of the ensemble (usually where the conductor stands, but not always). This is where the stereo pair goes. At first it will help to have the mikes mounted on the T-Bar and to hold them in your hand pointed at the band. Set each mike 45 degrees off of straight-ahead, giving you 90 degrees between each mike "head". Now, sort of "sight" each microphone by looking over the top of the mike head to see where it's pointing. Each mike should bisect the half of the ensemble that it's looking at. In other words, the left mike should be pointing halfway between the outside, stage left edge of the band, and the center or the band, and the right mike should be pointing halfway between the outside, stage right edge of the band and it's center. If it doesn't, step either forward into the stage of back away from it until that line-of-sight is achieved. If, for some physical reason (like the front edge of the stage), you can't get that far back, you can move the mikes further than 90 degrees apart to achieve that sightline, but realize that if the angle is too acute (say, more than 120 degrees), you might get a dead zone in the middle where there is insufficient coverage. On playback, this will give you the dread "hole-in-the-middle" and will destroy the stereo image. Avoid the temptation to adjust the pair to less than a 90 degree angle. This tends to lessen the the stereo effect. If you find that you can only get the proper sight-line by going less than 90 degrees, change your microphone pickup technique from X-Y to coincident. That should give you the stereo pattern you want at a closer range.   

Ideally. the microphones need to be behind the conductor, and should peak over his head. Microphones do rather well looking down on the ensemble being recorded. The best positioning ploy is to hang them from the proscenium. This can often be done if the band is playing in an auditorium with a formal stage and stage overhead. Often you can affix the microphones with nylon fishing line and sometimes you can get the auditorium's stage crew to help you. The downside of this arrangement is that it takes a lot of microphone cable to go from the mikes up to the stage fly-area and then over to the side of the stage and down to your equipment. Best results are achieved with the mikes about 5-7 feet above the conductor's head and slightly behind him.

Most of the time, though, you won't have the luxury of being able to "fly" the microphones and you will need stands. This can be awkward especially if the band is situated so far downstage that the conductor's position is near the front edge of the stage. Then you'll have to place your stand on the floor in front of the stage, and in so doing, lose about three feet of your stand's height. This is why it is necessary for you to have access to a really tall studio stand with a counterweighted boom for your mikes. 

OK, let's assume that you have placed your stereo pair of mikes as indicated above. Are you finished? Not at all. Some instruments are going to need highlighting. 

Highlight Microphones

Sooner or later you are going to come up on a situation where there are vocal soloists, or where some instrument is not being picked-up well enough to register properly in the recording. Another situation where a single stereo pair isn't good enough is when recording, say, a small jazz ensemble such as a trio or quartet in a club venue. All of these situations are going to require highlight microphones.

As daunting as this might, at first seem, It doesn't have to be if you keep a couple of hard-and-fast rules in mind. First of all, think about what you are trying to do. You are trying to augment the pick-up of a single instrument or voice against the overall stereo backdrop provided by the main stereo pair. You are not (in most cases) trying to make that instrument or voice dominate. Remember, while our ears can select and home-in on a single sound against a background of other, perhaps louder sounds, the microphone cannot. If, through your monitoring headphones, you cannot hear a particular instrument or voice, or, if that instrument of voice seems swamped by the rest of the musicians, then this instrument or voice is a prime candidate for highlighting. 

Secondly, you want this highlight mike to pick-up as little of the instruments surrounding the highlighted instrument or voice as is possible. This is controlled in three main ways. First of all the highlight microphone needs to be a cardioid mike. Omnis and figure-of-eight mikes cannot be used because, obviously, they pick-up sounds from more than one direction. Next, you can control the pickup by proximity. Place the cardioid mike as close to the instrument (or voice) in question as possible. Because cardioid mikes tend to accentuate low frequencies when they are placed close to the sound source, you might want to invoke the low-cut filter on the microphone - this is especially important if we're talking about a male vocalist or a piano. Lastly, you control the pick-up of adjacent instruments by bringing up the highlight microphone's gain just enough to fit-in with the rest of the ensemble, and no more. We want to hear it, but we don't want it dominate or call attention to itself (unless it's a soloist, of course).  You will need to pan-pot the highlight microphone visually to the same place on the left-to-right sound field as the instrument actually occupies in real space. If you don't, the pickup from the stereo pair and the pick-up from the highlighted mike will clash, confusing the image. Never, stereo mike highlights. if you do that it will bring the instrument or voice forward to stage center and again, will confuse the stereo image and even cause phase problems which can be very unpleasant to listen to. These "rules" are, as you can see, just common sense, and with experience, the correct methodology will make itself clear to you. 

In this recording, you can see the overall stereo mike in the right edge of the picture. Less noticeable, probably. is the small "lipstick" cardioid mike just inconspicuously peeking over the edge of the piano next to the piano's lid strut. It was apparent in the headphones during this rehearsal in the actual auditorium where the performance was to take place, that the piano was not projecting well enough, even though the open lid is pointing directly at the stereo mike. 

Recording A Small Local Ensemble

The easiest thing for amateur recordists to get permission to record is a small ensemble of jazz or pop musicians playing in local bars, coffees houses, restaurants and other public night-spots. Usually, it's not necessary to get permission from the venue management (why would they object to a couple of more pieces of paraphernalia in the musical group's "space"?), but it is vital that you get permission from the musicians themselves. Once the musicians have okayed you recording them (about which more, later), it's not a bad idea to introduce yourself to the venue management as the group's "recordist". 

Sometimes a little "background noise" consisting of people talking, glassware rattling, and in general, those sounds that accompany a restaurant, bar, or coffee house will add a bit realism and intimate ambience to a recording of this type, but, you don't want too much. This means that you will want to mike each instrument as closely as possible and separately in addition to your overall stereo pair (as opposed to instead of it). Many will tell you to eliminate the stereo pair altogether and just mix the individual instrument's mikes together. This is a personal choice, of course, and this will work. But you will end up with a "three channel" mono recording instead of stereo. 

For this example, we will assume an overall stereo pair and individual mikes on a trio consisting of a piano, a saxophone and a string bass. 

Showing arrangement for a small ensemble recorded in a restaurant, bar or coffee house.  Ensemble consists of piano, saxophone and stand-up bass. Notice that the stereo pair occupy mike mixer inputs 1 and 2, while the three mono highlight mikes occupy inputs 3, 4, and 5. Highlight mikes are cardioid and are moved close to each instrument to avoid pickup of audience noise. 

As can be seen in the illustration, above, a stereo-pair is still used to give overall ambience and stereo imaging. The highlight mikes are cardioid and placed as close as physically possible to the instruments. The saxophone mike can be troublesome because most saxophonists move around a lot when they start to "swing". If you can get the sax player to stand still, facing the microphone, good for you. Otherwise you might have to back that mike off a bit, physically and use more gain. Still, you are going to get a much closer pickup than the stereo pair will produce. 

Correctly pan-potting the three close-up or highlight mikes is crucial to maintaining the proper perspective. Of course, the stereo pair is panned far left and far right. The piano, which, in the example above, is on the left, is likewise panned far left. The sax, in the center of the group, is panned to the center, that is to say, equally in both the left and the right channel. and finally, the string bass is panned to the far right. 

As far as levels are concerned, you don't want the highlight mikes "louder" than the overall stereo pair. My advice is to start at about 25% the level of the stereo mikes. You will likely have to trim each from that setting to get a proper spread and perspective. Ask the musicians to give you some levels, either individually or together before you start to record. If they plan to play more than one set, you might choose to throw-away the first set for experimental purposes. Be sure to explain that to the musicians. If they are accommodating enough to give you levels before you record, then you are good to go. If you plan to record this group more than once, make note of the final levels and especially where the microphones are placed relative to the players so that you can repeat the setup. 

If you want to eliminate the stereo pair, as an experiment, you might actually like the result. Ever since the dawn of the stereo era, it has been traditional to record jazz in what is called three-channel mono where everything is panned into three distinct groups: left, center, and right. Of course, the center channel is a "phantom" channel because we are recording to only two actual channels, but it works fine. What you'll get is a really close-up presentation with little of the venue's hall sound or any of the noise resulting from an audience who will be eating, drinking and talking.  Just don't try this with a classical chamber group. It will sound awful (you wouldn't be recording a chamber group in a bar or restaurant anyway). 

Getting Permission to Record

Finally, a word about getting permission to record. The most important thing to keep in mind when approaching musicians is that you can give them something they want: A CD of the group performing. Promise them that right off the bat. tell them that you will give them each a CD of that evening's performance and that your services are gratis. It's usually enough to get you in. You should also promise that the recording you are making is for your own use and will not be used for any commercial purposes. I have actually made up a general contract that I take with me. If they seem reluctant, pulling out a contract that binds you to deliver the CDs and to not use the recordings for any purpose other than your own enjoyment, might turn a "no" to a "yes". Do a good job, deliver the CDs to them in a timely fashion, and you might find yourself getting calls from other groups. Musicians usually don't play exclusively with one group. One musician might play with this band one night and that band another. If you're good enough, word will get around. 

Next time we'll look at how to use the mixer. 

Microphones and Accessories

One cannot make an audio recording without a microphone. It's that simple. For stereo, you need two identical microphones. You also may need more than that for highlights and ancillary ensembles such as vocal choruses and soloists. 

Ask any ten recording engineers what microphone techniques they favor, and you'll get at least thirty answers. Everyone has their favorites, many are variations on the same ones, some might seem downright bizarre. But they must work, or they wouldn't be mentioned. When we get to that part of the discussion, I will tell you my favorites and explain all of the basic ones. Microphone placement is an art, an art that is learned through experience. But before you can fly, you have to walk, so we will start with microphone types suitable for recording.

Microphone Types

There are two basic types of microphones used in recording today, the condenser mike and the dynamic mike. Years ago, amateur recordists used several other types. One type was called a piezoelectric mike, often referred to as a crystal or ceramic mike and the fourth type of microphone that recordists used to use was the carbon-button mike, ubiquitous in the 40's, 50's and even the 60's neither of these latter types are used any more. 

Dynamic Mikes

Of the types of mikes used today, probably the easiest to understand is the dynamic mike. These microphones work by moving a membrane connected to a coil of wire in a magnetic field - like a loudspeaker in reverse. The sound strikes the membrane (or diaphragm) which causes it to vibrate in sympathy with the sound striking it. This causes the coil of wire to move with it. The coil, cutting across the lines of force set-up by a permanent magnet, induces a minute electric current to flow through the coil wire. This current is analogous to the sound waves striking the diaphragm. This current is amplified and can then be sent to a public address system or to a recording medium. Dynamics of this kind are often used as PA mikes or vocalist mikes. They are valued for their ruggedness and dependability and simplicity. 

A variation of this principle is called a ribbon mike. Instead of a diaphragm and coil, the ribbon mike uses a long, thin ribbon of some lightweight foil. The ribbon is usually folded like an accordion to get more surface area. The ribbon is suspended between the poles of a very powerful magnet. When the ribbon vibrates in reaction to being hit by sound waves, it, again, cuts across the lines of magnetic force and a weak current flows along the ribbon. Both ends of the ribbon element are connected to a transformer which steps up the tiny voltage created by this current flow and matches the ribbon's impedance (which is extremely low, usually less than an Ohm) to the microphone cable and amplifying circuit. Ribbons have such feeble output that they require a lot of amplification before they are useful. Even so, throughout most of the history of commercial broadcasting, ribbons were the preferred microphone for most radio stations. The RCA 44BX microphone, which is usually the mental image most people conjure-up when they think of a microphone, is, in fact, a ribbon mike.

The famous RCA 44BX. For almost two decades this mike was the voice or both radio and television broadcasting and most recording done here in the United States. To many people, this is what they think of when someone says the word "microphone". 

Ribbons are almost always bi-directional and pick up sound equally from both the front and the back. Due to the thinness of the ribbon, they are easily damaged by blowing into them or using them out of doors on a blustery day. While ribbons like those from Royer can be made with outstandingly flat frequency response (and concurrently high prices), most ribbons don't have a lot of top end. They are good for instruments with lots of midrange such as choruses and perhaps acoustic guitars. They are often valued for their very natural, warm sound and make beautiful announcer mikes (as long as the announcer doesn't blow into them).

Condenser or Capacitor Microphones 

Probably the most often used microphone for recording is the condenser or capacitor mike, as they are sometimes called. These mikes have always offered the highest performance and most accurate translation of sound to electrical current of any microphone technology. Although, condenser mikes have been around almost as long as has radio broadcasting and "electric" recording, really good ones, of the type we now associate with the technology, didn't appear until WWII Germany.

The Germans had developed two technologies during that war that absolutely dumbfounded the espionage types in England and other Allied listening posts. German radio stations would be broadcasting concerts of, say, the Dresden State Symphony Orchestra on nights when the Allies knew for a fact that Dresden (or Berlin, or Cologne, or Munich) was, at that moment. under heavy air attack. Two other characteristics of those "phantom" broadcasts puzzled the Allied listeners: The concerts were broadcast without breaks, tics and pops, and without the "scratchy" sound that usually accompanied transcription by phonograph record. The then only known method of recording sound for later broadcast. Add to that the fact that the recordings sounded so life-like and clear; they must be live!  It wasn't until after the war, when the Allies occupied Germany and went into their radio stations did they find the answer to this puzzle. The Germans had perfected the audio tape recorder, which, due to several German innovations (like AC bias for recording) turned out recordings that were unparalleled in their wide frequency response, low distortion and noise. The second thing they found was that the research arm of the German broadcasting ministry, Telefunken, in collaboration with the Georg Neumann company, had perfected the condenser microphone. Georg Neumann, another condenser mike pioneer,  had actually invented the modern condenser mike in the early 1930s. Called the Neumann "Bottle" it was used throughout Germany and developed all during the war. In 1947, Neumann came out with the famous U47 (also sold under the Telefunken name), which, along with the later U87 became the ubiquitous form factors for condenser Mikes. So much so, that most condenser mikes today, irrespective of what they cost or where they are made, look like one or the other.

After WWII, both Telefunken (Left) and Neumann (right) came out with the first successful condenser mikes for recording, the U47. Here in the USA, they unseated the RCA 44BX as the microphone of choice for recording and broadcasting, ushering-in the era of high-fidelity - just in time for FM broadcasting and the LP. 

Operation

The condenser mike works in one of two ways. Both types work because the diaphragm and the back plate of the microphone element form a small capacitor of about 40-50 picofarad. In the most common application, this capacitor is charged with a polarizing voltage which is used to control an amplifying device such as the grid of a tube, the base of a bipolar transistor or the gate of an FET. The sound striking the diaphragm varies the capacitance of the mike capsule coupling more or less voltage to the control element of the amplifying device causing that device to conduct either more or less and the resultant signal is analogous to the sound striking the diaphragm. The second method uses a similar capacitor to the above example, but instead of that capacitor controlling the coupling of voltage to the microphone circuitry, this second method has the capacitor as part of a tuned RF oscillator circuit. The audio, striking the diaphragm, changes the frequency of the oscillator, also as an analog of the sound being picked-up. At the output of the microphone, a detector circuit called a discriminator strips the RF frequency from the signal leaving only the audio modulation. This works a lot like an FM radio, and indeed,  is often called an FM microphone. While there are still some FM microphones being made, most condenser mikes are of the first type.


The biggest drawback to the condenser mike has always been it's requirement for an external power supply to polarize the capacitor mike capsule and to drive the electronics. Pre-solid-state, most condenser mikes relied upon dedicated power supplies and special cables with multi-pin connectors to connect the mike to the supply. These cables had to carry both the audio and the various voltages such as the B+ and filament voltage for the tube(s) as well as the polarizing voltage for the capsule. Generally speaking, the link from the power supply to the recording console was via standard XLR cables. Extension cables between the mike and power supply were non-standard and usually quite expensive. After condenser mikes became solid-state, in the late 1960's, the separate power supply was abandoned in favor of so-called phantom power. Phantom powering uses 48 volts (this came from the telephone industry) DC which is piggy-backed on the same wires that carry the audio from the microphone to the mixing console. The DC doesn't affect the audio and today, most mixers have the 48 volt phantom-powering power supply built in. More expensive mixers allow you to apply the phantom-power individually to each microphone input, while cheaper mixers merely allow one to turn it on or off globally to all microphone input circuits. 


The Electret Condenser Microphone


In the late 1960's after solid-state electronics became possible inside the microphone itself, the need for tubes and the high-voltages they require was obviated. This allowed practical application of a type of condenser microphone capsule called an electret. An electret is a stable dielectric material with a permanently embedded static electric charge. Due to the high electrical resistance and chemical stability of the materials used, the electret device will retain it's charge for hundreds of years. Although the electret principle was discovered in the 1920's, it didn't become practical until two Bell Labs engineers designed one using a thin Teflon coated metal foil as the electret in 1962. The combination of the two maturing technologies, the materials technology for the electret itself, and the use of the FET transisitor for the amplifier, suddenly made this kind of microphone practical. Due to the fact that an electret condenser microphone does not need a polarizing voltage, and the FET amplifier in the mike draws very little current, suddenly, small, cheap condenser mikes which ran on batteries became possible. The biggest application for these mikes, became, of course, in telephones to replace the century-old carbon button mike. The improvement in voice quality was apparent to everyone who heard one of the new electret miked phones.

Schematic of a typical Electret Condenser Microphone showing how simple it is. Often, these mikes can be powered by a single watch battery yet provide long battery life and better performance than the cheap carbon, crystal, or dynamic mikes that they have replaced. 

 It wasn't long before companies like Sony, in Japan, were applying electret principles to recording microphones. In the early 1970's, Sony introduced the ECM-22p a professional quality electret that could be powered by either a nine-volt battery or via standard 48-volt phantom-powering. The ECM-22p sported rugged build quality, and surprisingly decent frequency response. Sony spec'd the mike at 40-15,000 Hz, but I've found that the two that I owned to be rather bass-shy. However they are great on the top end and midrange and make excellent drum mikes. After having owned them for almost 30 years, I can say that they still work as well today as the did when new (although the Eveready #206 9V batteries are somewhat hard to come by these days - thank Sony for making them standard phantom-power compatible).

Early pro electret condenser Microphone the cardioid Sony ECM-22P

Although a number of electret microphones for pro use have been made, most are small-capsule mikes designed for the low-end consumer market. When I was in Japan a number of years ago, I picked up a Sony electret single-point stereo mike (ECM-929) to use with my Walkman-Pro cassette recorder. This mike has been excellent with it's M-S pick-up pattern and adjustable soundstage width. But like most electrets, it's tiny capsules make it a bit shy on bass and definitely suited only for casual recording (see the second installment of this blog for a picture of this microphone photographed with a Sony MiniDisc recorder).  

Modern Condenser Microphones

For most of the post-war era, condenser microphones were considered the Rolls-Royce of microphones. They cost a bundle. Even today, A Neumann condenser mike like an M149 can easily cost close to $6000! When I was in the recording business in the 1970's I owned a pair of "cheap" Japanese condenser microphones from Sony called C-37Ps. These had an FET amplifier in them and a single capsule that was switchable between omni-directional (non-directional) and cardioid (uni-directional). They cost well over $1000 in 1975 dollars and were considered inexpensive compared to Neumann, AKG, and Beyer condenser mikes of the time. 

Sony C-37P FET Condenser Microphones were considered "inexpensive" at about $500 each in the mid 1970's. They are still very good microphones, by the way and command top-dollar when they show up on the used market. 

Enter the Chinese

From 1949 until the death of Chairman Mao Tse-Tung, China was a closed country. They did not trade with the west, and, essentially, had no consumer markets as existed in the west. Like the Russians, the Chinese reverse-engineered (read that "copied") essential technologies from western manufacturers and simply made their own. One of these technologies was microphones. All the best condenser mikes had "Chinese copies" and they were used in both broadcasting and recording. When the Bamboo Curtain fell in the 1980's, it was found that these copies of Neumanns, AKGs, Telefunkens, Scheops, Sennheisers, Beyers et al, were actually not half bad, and available for mere pennies on the dollar compared to their western counterparts. 

As soon as trade agreements with western companies became possible, many people decided to have their own microphone designs built in China. That brings us to the present glut of excellent and cheap condenser microphones which not only are well made, but actually perform very well. It is possible to buy Chinese-built microphones from firms such as Avantone, Behringer, Samson, Rode, and many others. 

Most of these mikes are better than the classic mikes from which they are copied. The reason is that the classic Neumann and Telefunken models (not to mention AKG and Beyer) had acid-etched brass diaphragms, which, while thin and light by the standards of their day, are today, so massive that they gave these microphones a peaky, rising top end which can sound harsh, especially when used to record digitally. Modern condenser microphones, including Chinese ones, have diaphragms made from a thin Mylar plastic which has been "sputtered" with an atom-thick coating of either aluminum or even gold. The metal coating on the Mylar makes the diaphragm a conducting capacitor plate without adding any weight. The resulting diaphragm is so low in mass that it's fundamental resonance (the characteristic that gives the older mikes such an aggressive top-end) is pushed way up into the ultrasonic region of the audio spectrum, where people cannot hear it. Modern mikes, even inexpensive ones, therefore tend to have a smooth, clean sound that shames most older designs. 

One Chinese made mike that I have used and found to be just about the best mike I've ever used  is the Avantone CK-40. This stereo mike has switchable patterns between omni-directional, figure-of-eight, and cardioid and is actually two microphones in one case. The top element can be rotated either left or right 90 degrees (for a total of 180 degrees relative to the lower element). Physically, it is a close "copy" of the famous (and fabulously expensive) Telefunken ELA-M-270 from the 1950's which is still made and can still be purchased new from Telefunken USA for a mere $16,000. The CK-40, on the other hand lists for about $600 and instead of being tubed like the Telefunken, features an ultra-quiet FET preamp. 

The Avantone CK-40 (right) can be said to be a virtual "Chinese copy" of the famous Telefunken ELA-M-270 (left shown without its shock mount). Having used both an original ELA-M-270 and the CK-40, I can tell you that while both microphones are good, the Avantone is much better and, in fact, is one of the best sounding microphones this writer has ever heard.

Choosing Microphones for Your Own Recording Set-up


There are a number of characteristics that one needs to keep in mind when choosing microphones for recording. Generally speaking, the larger the capsule diameter, the better the bass. Most decent condenser mikes, these days have at least a 1-inch capsule and I would consider this a minimum for any mike that will be used for general coverage of an orchestra, symphonic band, or any ensemble with a wide range of instruments needing a solid low-end foundation. Affordable microphones that meet this criteria are, happily, fairly abundant. The Samson CO1 at around $80 is an excellent entry into this type of so-called "big-capsule" microphone as is the SM-ProAudio MC01. Both of these cardioid-only microphones are excellent performers and superb values. For multi pattern mikes, the $150 Samson CL8 is a very good pick and offers a choice of cardioid, figure-of-eight, and omnidirectional patterns. Also in this range is the excellent Behringer B-2Pro. All of these mikes have excellent, wide frequency response and solid bass performance. Of course, I cannot heap too much praise on the aforementioned Avantone CK-40 stereo mike. This dual-head single-point stereo mike has large 35mm diameter capsules and among the best low-end performance that I have heard. When coupled with this mike's smooth midrange, clean, flat top-end and wide dynamic range. it's hard to beat - at any price.

Behringer B-2Pro multi-pattern, large capsule condenser microphone shown with included accessories

There are always going to be situations where you are going to need more than just a single stereo-pair of microphones to get proper coverage of the ensemble you are recording. When recording a jazz big-band recently, I found that the stereo pair was not picking up enough of the piano. Listening to the ensemble play from the audience perspective, I could hear the piano, but when listening to the mike feed on headphones I could not. This necessitated the use of an auxiliary microphone on the piano and mixing the result into the overall pick-up from the stereo-pair. To do this I used a single cardioid SM-ProAudio MC01. This mike was placed low so that it just "peaked" over the edge of the grand piano and was aimed at the center of the raised top. I pan-potted the mike to the extreme left (the piano was on the extreme left side of the band) and raised the level on the mixer input so that the piano could just be heard in the headphones. The results were perfect.

This means that you are going to need more than just one pair of microphones. It is not necessary that these mikes have the bottom end of the main mikes as they are usually just for accent. Sometimes there will be vocalists involved and these mikes will work fine for that as well. A typical microphone complement for a modest amateur recording "kit" might be:

1- Avantone CK-40 single-point stereo mike (or equivalent such as a pair of Behringer B2 Pros on a 'T-bar'.

2- Behringer B2 Pro multi-pattern microphones (or equivalent switchable pattern mikes).

2- Samson CO1 cardioid large capsule microphones or M-ProAudio MC01(or equivalent)

2- (a matched  pair) of "lipstick" small capsule microphones (Behringer C-2, C-4 or equivalent)

 

Author's Microphone complement for location recording. Each mike has proved itself to be rugged, well made, and a good performer. 

Needed Accessories

Missing in the above pictures are two very important components. The first is microphone cable. Since you never know where you are going to end-up, it is important to always have enough. My rule of thumb is to carry 4 -50' lengths, and eight 25' lengths. This looks like a lot, but I'd rather carry too much than too little. It is rare that you'll ever need more than three or four microphones for any one gig, but you never know what you might run into or how far away from your microphones that you'll be setting-up. 

Cables

Now, about cable. Naturally, it needs to be balanced microphone cable with decent quality XLR connectors; a male on one end and a female on the other. Other than that, if you buy from a reputable source such as Shure or Hosa, you can be assured of getting decent quality. Let me clear something up about cables right now. I spent years in the aerospace industry as a wiring/cable engineer for some of our country's most leading edge rockets and satellites. I have studied wire thoroughly and I can tell you this, just between you and me: at audio frequencies, wire is wire. Oh, I know, you can spend a fortune on cables from high-end audio cable companies, but it's all bling; stuff and nonsense. No double-blind cable test has ever revealed any difference whatsoever between expensive and cheap cables. Audio cables have no sound of their own. So buy well made, reliable cables from reputable sources and don't worry about the rest. One thing is important, however, and that is to use runs as short as possible and keep the number of connectors between the console and the microphones as low as possible. In other words, one long cable is better than two or three shorter ones connected together. 

Mike Stands

Now you need something to set the mikes on. Floor stands are fairly cheap, and the best kind for location recording are the folding kind. I use four of the Euroboom OS13 stands. These microphone stands have a folding, three legged base and a column which raises to about 63" and a boom that gives another 33" of extension. They weigh only about 5 pounds each, fold very compactly and can be bought online for about $30 each. For the big (and heavy) stereo mike, I use either a Euroboom with sandbags on the legs (for stability) or I use the foldable StuBoom from On-Stage ($120). This stand extends to 80" and the counterweighted boom gives another 82" of extension. This stand is heavy, and large. I only use it where I have the room for it and I don't carry the boom very often because it won't fit in my car very comfortably (being almost 7 ' long). But it is there when I need it. Check around, you can find some very decent mike stands out there. If you have a music store in your area, you might ask them to be on the lookout for used stands for you. I once bought a huge studio boom with a cast iron base for $20 at a local music store. New ones are almost $300 today. I ended up giving it away because I couldn't easily carry it around. Deals are out there.

Next time we'll talk about microphone pick-up patterns and how to mike various instruments for best effect.

Microphone Mixing and Pre-amp Options

This time we are going to discuss how to get the microphone signal to the recording device. For this discussion, we are going to assume a two-channel stereo recording, but, keep in mind that these things apply to multi-channel recordings as well (whether they are mixed to two-channels for production or to 5.1 channels or any other surround-sound format.)

Professional quality microphones, whether condenser, or dynamic have one parameter in common: they all need to be amplified before they can produce a recordable signal. Usually, microphones need between 40dB (100X amplification) and 60dB (1000X amplification) to get their signals up to what is regarded as "line level" which is required to give maximum record volume. Some microphones, such as ribbon mikes have such low output that sometimes as much as 70 or even 80dB of gain is required. This means that pre-amps required for microphones must have the following characteristics: They must be quiet, have low distortion, lots of headroom and wide, flat frequency response. They also must have differential inputs to take professional "balanced" microphone cables.

Noise, is a major factor here. At these levels of amplification, the "self noise" generated by active components such as bipolar transistors, FETs,  Integrated Circuit (IC) operational-amplifiers (op-amps) and vacuum tubes becomes a major factor in the quality of the finished recording. Much of this self-noise is thermal. Active electronic components use the physics of electron attraction and repulsion to move signals around and to amplify them. Moving electrons through the devices creates a certain amount of random, or non-correlated noise (along with heat). In fact, vacuum tubes (or valves as they are sometimes called) operate by heating an element inside the tube hot enough to actually "boil" electrons off of its surface. The rest of the tube's elements (the grid(s)) control the flow of those electrons and actually determine how many of those boiled electrons get passed it and on to the plate where they constitute the amount of current that the tube conducts; I.E., less current flow represents small signals, more current flow represents larger signals. Since all of the tube's amplifying ability comes from the fact that it is a heat-operated device, the amount of random electron flow, and thus noise, is characteristically quite high.

Solid state devices work differently, and while they still create heat it is much less than a tube, and rather than the heat being the method of operation for these devices, it's more of a by-product with them. While noise is still an issue, generally speaking, solid-state electronics are much quieter than tubes. Does this mean that tubed electronics cannot be used to make modern digital recordings? Not at all. The reason is because there is another way to get voltage amplification of a microphone signal; transformers. Voltage gain, in a transformer, is largely a matter of the turns ratio of the transformer's coils between the "input" (the primary coil) side of the transformer and the "output" side (the secondary coil). As an example, if you put 10 turns on the primary windings (coil) of a transformer, and 100 turns on that transformer's secondary windings and apply a one-volt AC signal to the primary, you will get about 10 volts out of the secondary. This is an oversimplification, but it does show how the voltage gain of a transformer is determined by it's turns ratio. Since the transformer is not an active component, it adds no noise, but it will amplify any noise in the signal applied to it right along with that signal. There is no free lunch, after all. So if we take the output of a good mike with decent noise characteristics, feed it into a transformer before applying it to an active microphone preamp, it is possible to get by with far less gain in the preamp itself. Less gain equals less thermal noise being added to the signal making it very feasible to use tubes in modern microphone preamps and still get signal-to-noise ratios that are compatible with even high-resolution digital recordings. Of course, there is a downside with transformers. Good ones, which have flat frequency response across the entire audio spectrum are expensive. Transformers also have problems with maintaining phase integrity at all frequencies and especially have problems coupling low frequencies through them. Most modern solid-state microphone pre-amps and mixers don't use transformers, but use a type of input circuitry called a differential amplifier. These are very good at rejecting noise that is common to both legs of the balanced interconnects from the microphones. These include, hum, air conditioning spikes (when the compressor cycles), noise created by the proximity of light dimmers in auditoriums and other public venues, etc. This ability is called common-mode rejection.

These days, a decent microphone preamp will give signal to noise ratios of somewhere in the region of  about -125 to -130dB, the greater the number, the quieter. Any microphone preamp with figures in this region will give recordings that are, for all intents and purposes, essentially silent. Even with the playback gain set quite high, one should hear nothing but blackness when no instruments are playing. 

Another characteristic of microphone preamps to consider is headroom. Live music can get quite loud. Cheap preamps can clip (distort) when fed a microphone level that's too high. Modern condenser mikes can handle sound pressure levels of as much as 150dB before clipping. It would seem like it would be nice to have a microphone preamp that had similar characteristics. Thankfully this isn't necessary. All microphone inputs have controls on them to vary the amplifier's gain and most have a light on them to indicate when that mike channel is clipping. A rule of thumb here is that the louder the source is playing. the less gain is required from the pre-amp. It is always advisable to ask the ensemble's leader to have them play the loudest part of their program before the recording starts so that you can advance the gain to clipping, and then back-off until the clipping indicator light goes out for all microphones. Then, back-off a bit more - just in case somebody wasn't really playing their loudest. This insures the highest possible signal-to-noise ratio without worry of overdriving the microphone preamps. Some recording engineers use a calibration box on each input to feed a signal of known amplitude into each microphone preamp. This might work in a studio situation where things like room-loading and individual microphone characteristics are well known, but for location recordings, I'd rely on the actual musicians to tell me how loud they're going to play rather than count on some unrelated "standard". After all, conditions will vary from venue to venue and musical group to musical group. No two situations will ever be the same. Of course, if you are in a position to record the same group in the same venue time after time, experience will guide you in setting your microphone preamp gain. Ultimately, the amount of overload protection built-into one's microphone preamps is down to their design. The higher the power supply voltage feeding the amplifiers, the more head-room they will have. On modern mixers, even fairly inexpensive ones, this shouldn't be a problem.

EQ

Many mixers contain, for each input, a group of controls called "EQ" or equalization controls. These are essentially, "tone controls". Usually there are at least three and sometimes more. They are usually marked "high", "mid" and "low". Sometimes the frequency at which they come into effect is also marked on the mixer and sometimes that frequency has its own control and can be varied somewhat. There is usually a set of these for each input on the mixer. If one is doing an 8 or a 16-track recording where the mix will be finalized at a later date and every instrument or instrument group has been assigned it's own microphone channel, then I can see where such controls would be very useful. On the other hand, most of the types of mixers that are used for location recording are "X" number of channels in but only two channels out and are designed for mixing on-the-fly while the performance being captured is actually occurring. So, no matter how many mikes you are using, the end result is two channels recorded to media, and that is cast in stone. There is no going back and "tweaking" this mike feed or that one. Since there is no way to "undo" an injudiciously applied amount of EQ in these cases, I tend not to use it. The exception would be if I had a certain microphone that was deficient in some way (like a ribbon mike that had little response above about 10 KHz) I might use a bit of EQ on that channel to accentuate the area that was a little lacking. It is also possible to judiciously add a little presence to a vocalist by lifting the midrange a bit, or to reduce the chestiness in a male vocalist's voice by reducing the bass on his mike's input. Other than that, I feel that it's best to leave these controls out of the picture. They're great to have when you need them as long as you keep in mind that a little goes a long way, and the results are not reversible.   

Each microphone mixer or pre-amp has its own features such as built-in reverb effects, or busses for external effects and it is beyond the scope of this article to discuss them. But what I do think is necessary is to talk about the size of mixer needed for location recording. 

When I got back into recording after a long hiatus (see the first installment of this blog entitled "Commercial Recording Quality"), I figured that since all of my earlier recordings had been made with mostly two microphones, and when confronted with a chorus as well as an orchestra, a maximum of four, that a four microphone input mixer would more than suffice.

Behringer 1202 Mixer sports four excellent microphone inputs and 8 line-level inputs. These can be had for less than $120

When I bought the above pictured Behringer 1202, I was astonished by the street price of just a hair over $100 (US). My previous mixer, a TAPCO, had cost about $1200 and wasn't anywhere near as good. Behringer calls their microphone preamps in this line of mixers "Xenyx" pre-amps and they tout them as being very quiet. They are. I have made some astonishing recordings with this mixer. The circuitry sounds so good and is so quiet that instruments just "appear" out of a velvet black background. I realize that manufacturing this mixer in China (from a German design) is part of the reason for the low-cost, and the advancements in solid-state technology is responsible for the rest, but still, I was blown away by the quality. Soon I realized, however, that the types of recordings that I was doing required more than just four microphone inputs. Not the least reason was because I was using a stereo microphone in the M-S pattern (which will be discussed in another installment), and that required three microphone preamps to yield two channels. That left one. Realizing that I needed more microphone inputs, I went back to the Behringer catalogue and found the 1832FX. This mixer sported 6 microphone inputs as well as built-in reverb effects. I hesitated due to the size of this mixer (one more thing to carry). It is much larger than my 1202. But I figured that where the 4-input 1202 was sufficient, I could cary that, and where I needed more, I could carry the 1832FX. 

The Behringer 1832FX Mixer has 6 of Behringer's excellent "Xenyx" series microphone pre-amps and 8 line level inputs. It also sports built-in digital special effects and a graphic equalizer on the outputs. The street price on this mixer is around $250.  

While I have chosen Behringer mixers, that doesn't mean that there aren't others just as good, and while I find the Behringers excellent performers and suburb values, Mixers from Peavy, Mackie, Allen & Heath,   Edirol and Yamaha are probably just as good. Choose according your projected needs and keep in mind that you will have to tote around whatever mixer that you eventually choose. If you do find, at some point down the road, that you need more microphone channels than your current mixer can provide, that there is another alternative to buying a whole new mixer.

Add-On Microphone Preamps

Most mixers on the market today come equipped with a certain number of microphone preamp stages. In the case of the Behringer 1202, that number is four, and with the 1832FX it's six. The Peavy PV20, for instance, is close in price to the Behringer 1832FX and offers sixteen microphone stages but lacks the Behringer's comprehensive features list.  It is also immense. Many of these same mixers also have a number of line-level inputs. While these, lacking the gain, are not designed for microphones, but rather for other sources such as recorders (for mixing-in pre-recorded material and adding to it), and even other mixers. My Behringer 1202 and 1832FX both have 8 such inputs and other mixers may have similar. This is a perfect application for outboard microphone pre-amps. These devices can be had for as little as about $35 for a single-channel tubed unit from Behringer up to several thousand dollars. SM Pro Audio sells an excellent 4-channel solid-state microphone pre-amp called the Q-Pre4 which is available for a street price of less than $80. For my purposes, the Behringer, again, proved to have the most bang for the buck. Behringer's MIC100 is a solid-state, stand-alone, single-channel microphone preamp with a tube output buffer to impart "the tube sound" to the microphone being fed it. The 12AX7 vacuum tube used is not for gain and therefore adds no appreciable noise. You will, of course, need one for each extra microphone you connect. For either Behringer mixer, that means eight in total. I carry two in my recording kit and have even used them in place of an entire mixer when only two channels are required! They sound excellent and would, in fact, constitute a fine starter system. A pair of MC100s, a pair of decent big-capsule cardioid condenser mikes such as the Samson C01 at less than $80 each (street price) or a pair of Behringer Pro 2Cs (multi-pattern mikes) at slightly more along with a Zoom H2 solid-state recorder and you will be recording 24-bit, 96KHz stereo recordings for a a maximum investment of only about $500! This kind of price/performance combo would have been unheard of just a few short years ago.

The Behringer MIC100 Tube buffered Microphone preamp. At $35 street, it's excellent and hard to beat for flexibility and control

The SM Pro Q-Pro4 4-channel Microphone preamp. at around $80, it would be hard to go wrong having one of these in one's kit

Next time we'll discuss Microphone types and how to deploy them...