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Record 1 “Give a man a fish; you have fed him for today. Teach a man to fish; and you have fed him for a lifetime.” Proverb - author unknown As with all I write in these chapters, you should find your own context, and the images that fit best. I think that suggesting a few starting points in this complex field is more efficient than trying to dive into debatable details. So, as before a fishing expedition, you might gather nightcrawlers on the starlit humid lawn of your home, and check all your gear; before a recording session, you might mull over your objectives, and prepare your tools. We’ve been lucky in the past 100 years or more to come to a point where a musical project can be very well recorded with fairly inexpensive and easily available equipment. We’ve been even more lucky that the boundaries of what is considered music have been pushed far enough to include almost any imaginable existing sound, as well as sounds resulting from synthesis of all sorts. I will use the fairly representative idea of capturing sound in a small studio, coming from typical instruments, as the jumping off point, but the fish you almost caught is not necessarily the same one that got away from me.
Record 2 After the long chapter on Sound Analysis, you know that sound is a slippery eel, and to catch it you need imagination and appropriate strategies. A typical acoustic recording chain may consist of the sound waves being captured by a microphone on a stand, traveling down its cable, through a preamplifier, and landing on the recording medium - the fishnet. Global decisions can orient your recording session, such as: Do you want to capture the reverberation of the playing space as well as the instrument - drums in a stairwell, anyone? - or primarily a dry, close up sound directly from the instrument? Do you want effects on the sound as it is played or the possibility of adding them later? Will the musicians feel best and give their best with you in the same room, or do they feel better in a more private space? If several musicians play at the same time, do they need to send each other visual clues concerning changes in the music, and is the full on composite sound of «all at once» better than isolation booths cutting down on inter-microphone bleed?
Record 3 These and many more are the preliminary thoughts that give a bit of architecture to your recording session. Most approaches are valid if they fit the final goal of the project, but some are more difficult to get from the water to the frying pan! As you probably wouldn’t use tweezers to pick up an elephant, or a butterfly net to capture a boa, give some thought to your end goal before choosing and setting up your equipment. For now, from sound source to recording medium, let’s look at microphones, cables, stands, and pre-amplifiers etc. All elements in the recording chain are important and should be of high quality in their conception as well as in their mutual interaction. As we go through the chain of recording tools, it may seem that I favor some elements more than others, but some present more complexity and the choices are wider whereas others, being straightforward, need less words. Just remember that a weak link is just that, and that the subtle details of sound may be diminished anywhere along the chain. Even though I referred to sound as a slippery eel, it may be better to see it as something very fragile, like a butterfly,
Record 4 and to see our goal as capturing it with as little damage as possible to its delicate wings - its frequency and dynamic range. This is where the first tool comes in - the microphone. You wouldn’t use night crawlers to catch a shark, and the choice of your microphone should be adapted to the nature of the sound to capture. Jimi’s guitar isn’t a theremin, and Armstrong and Callas had slightly different vocal timbers. How can we find the right microphone for the right sound? A first distinction can divide microphones into two general families, those whose capturing element - diaphragm - has only one side exposed to the sound source, «pressure microphones», and those which allow exposure to both sides, «pressure gradient microphones» and calculate the difference in pressure variations on the two surfaces. The advantage of the second type is its sensitivity to direction, similar to the combined information from two ears, and its control of the capture field. The first type is more of an omni-directional tool, like a rather larger butterfly net. Capsules have been conceived using various materials, including carbon granules (the first telephones),
Record 5 crystals ( piezo - pressure), moving coils (dynamic)and condensers (capacitors). Of these four most well-known types, the carbon is the least used now, and piezo types can be seen mostly in acoustic stringed instrument bridges, so we will just be concerned with the last two families generally known as dynamic and capacitor, as they are the ones most often used on stage or in studios to capture voice and instruments. Directional response can be engineered by capsule design and other factors, so that the distinction is sometimes not straightforward: a dynamic can be directional, and a capacitor can be omni-directional. Fortunately, most serious microphone builders provide a simplified schematic representation of the microphones directional sensitivity, called a polar diagram, where the center dot represents the microphone capsule. Dynamic microphones include the common hand held microphones seen in live stage performances as well as the more fragile ribbon microphones. Often the diaphragm of the dynamic microphone will be slightly dome shaped for more rigidity, but this may compromise response in the higher frequency range. Certain microphones use two elements to capture the high and the low frequency information.
Record 6 The structure of the capsule housing can be designed to allow directionality, and this allows what might be an omni based idea to function in cardioid or other directionel patterns, exploiting phase differences and cancellation etc. The diaphragm is moved by the incoming sound and a coil of wire attached to it will also vibrate in proximity to a magnetic field. This generates an electrical signal analogous to the sound pressure changes in the air at the front of the capsule, and will be sent down the cable to be recorded. Dynamic microphones are the rough boys of the music world, good for drums or PA systems or potent singers. Ribbon microphones are their more fragile counterpart, and are of the pressure gradient type, since the delicate folded ribbon is exposed to the sound waves on both sides, and its sensitivity is greatest at front and back, with maximum rejection at right angles - left and right. The metallic ribbon itself moves within a magnetic field, as did the wire coil in the moving coil microphone, and thus generates an electric current. High frequency waves are more directional than low frequency waves, and the normal polar pattern for a ribbon mic is a figure 8, although if an acoustic delay system is added to the backside
Record 7 of the ribbon mic, directionality can be modified. The lightness of the ribbon allows for better high frequency response, but renders these microphones more susceptible to handling noises and to bursts of air - they are to be handled with great care and respect, and can give excellent results with woodwinds and brass instruments, etc. The condenser microphone family uses the variations in capacitance provoked by the changing distance between the diaphragm and a back plate charged by the phantom power - often 48 V provided by the pre-amplifier or other source. The space between the diaphragm and the back plate is very small, allowing even the very slightest movements in the air to be transcribed as voltage changes across a resistor, then slightly amplified by the head amplifier in the lower part of the body of the microphone. The diaphragm and back plate assembly can be miniaturized enough to almost act as a point shaped omni-directional microphone or can have a larger diaphragm for cardioid patterns, and others in between. In general, since the condenser mics are quite sensitive, care must be taken to avoid unwanted proximity effect (bass boosts) or other handling noises.
Record 8 A sturdy microphone stand is best, and a good suspension for the microphone itself. In studios, condenser mics tend to be the most visible for acoustic instruments and voice, and their quality and characteristics range very widely. “If the mic fits, use it.” This is a starting point. It’s up to you to read about recording sessions and microphone techniques in various contexts and then find your own microphone alchemy. Before leaving the microphone for other parts of the recording chain, let me just mention a few other options you may not know of. Lavalier mics are those tiny black cylinders often attached to the clothing of someone being interviewed, they can tend to boost bass and not capture sibilance well, but they are discrete. Shotgun microphones have a very long cylindrical body with many slots that favor the sound they are pointed at since it takes a straight path to the diaphragm. They allow choosing distinct sound sources from a distance. Acoustic boundary microphones - or pressure zone microphones «PZMs» have small, usually electrostatic elements housed in some plate shaped - circular or triangular etc. - surface, which can capture vibrations from the surface upon which they are placed.
Record 9 This summary of the various microphone types has obviously left out those that you know, that I don’t know, and some features such as bass rolloff switches or other handy items have not been mentioned, but we are ready to now move from the capsule to the cable, and so on we go! Most high quality microphone cables use a minimum of three internal wires, and are called balanced. One of these wires sends the phantom power to microphones using capacitors - condenser microphones - and there is a clever noise rejection system in the other two wires for the audio signal. One should not skimp on the quality of the cable and its shielding, but exorbitantly priced cables do not always offer more than well conceived lesser priced cables. There exist other cables for other purposes such as plugging in instruments or working with patch bays or for headphones, etc., but for now we are concerned only with capturing sounds through the microphone. As you could easily imagine, the stability of the microphone support is very important, and anyone who has held a camera or a telescope zooming in on a distant object, has seen how difficult it is to get a steady image.
Record 10 The microphone is trying to capture the sound vibrations or pressure changes in the air, which are like waves with crests and troughs. If the diaphragm or capture element of the microphone is moving, even slightly, it will blur the distance between the crests and may give a less precise image of the higher frequencies it tries to capture. Imagine being at the scale of the high-frequency waves, and trying to catch the crests with an equally small net - if you are jiggled but the waves are not, you will be hardpressed to focus your net on the crests. That is why the more sensitive microphones have a suspension that has an elastic character to dampen any jiggling that may occur of the microphone’s position. A well conceived microphone stand will give a solid base upon which the suspension is set. And care should also be taken to ensure that a tapping foot of an excited musician will not be translating as rhythmic bass thuds during the recording - unless of course you want that added realism. If you listen carefully to piano recordings you can often hear the thuds of the foot pedals resonating with the piano. Many types of stands exist, including stereo microphone suspension from ceilings for orchestras or large choral groups. Find the stand most fitting to your recording situation.
Record 11 So, to resume, we now have our butterfly net, our microphone, and its stand and transmission cable. We now must become aware of the very important question of microphone placement. To begin with, let’s use the example of a single instrument or voice. You can apply these ideas to any sound source, so as you read on, simply try to slide yourself into your planned recording session. The propagation of a single point sound source may be approximately seen as a growing sphere, or a balloon being blown up. The audio information seems to be symmetrically spreading away from the source. Now, the harder parts! In fact, a point source idealized like this is very rare. Most objects that produce sound also resonate with the sound they are producing, and the resultant propagation of the sound can become very complex. Typically we may see a stage with, for instance a saxophone player holding the bell of his instrument near the microphone; or maybe a singer keeping an up close stance in front of their microphone. Leaving aside the previously mentioned proximity effect that can enhance or exaggerate the bass frequencies, we should be aware that the character of any instrument can be modified creatively by correct microphone placement.
Record 12 Our best tool in this situation is our ear, and a good learning process is to allow the musician to warm up, and to slowly move in and around his instrument while listening for subtle timbral changes. The goal would then be to capture what you both think would be the most pertinent aspect of the sound. This can help for the direction that the microphone will face, and further experimentation will help clarify the distance from the sound source that works best with the overall dynamics of the song and the desired ambiance. Anechoic chambers have been used in conjunction with very precise recording processes to discover the propagation characteristics of various instruments. Detailed information is then discussed with instrument makers and can sometimes bring about improvements in instrument design. Let’s accept our work up to now as being well thought out and optimized for our goal. We have chosen the microphone, the stand, the cable, and the position of the microphone. We now must see where those electrons running down that cable will go. Next stop: a pre-amplifier! Situations can differ in recording facilities depending upon individual taste and money available, but in general it will be necessary
Record 13 to boost the signal captured by the microphone to a stronger level by the use of a pre-amplifying system that is different from a guitar amplifier or a stereo amplifier. It may be included in the mixing console, or as a stand alone box, but the idea is the same: to get a healthy, clean signal to the recording medium. As with the choice of the quality of the microphone, the cables, and the stand, it is important to match the quality of the pre-amplifier to the other elements in the recording chain. The captured signal will be amplified, but so will any parasitic background noise, and so you need as clean a pre-amplifier as possible to avoid adding its own noise to the signal. Very high quality microphones often have their own separate pre-amplifier sold as an accessory, thus assuring an optimum match. Some microphones have a built in system in the microphone body. Systems can be analog - with or without tubes - or digital. Most have a signature sound that experienced engineers recognize easily and exploit specifically for their inherent frequency shaping. It may seem a logical idea to look at the specifications and search for the flattest response in the audible frequency range. This could be a good tactic when you only have enough money
Record 14 for a single microphone and a single pre-amplifier, but professionals know which microphone and preamplifier combinations flatter the voice or specific instruments, and use these as starting points for capturing the sounds most suited to the project at hand. What ever guides your choices now, it is a very good idea to follow the yellow brick road to a professional forum on the Internet to discover the mass of detailed information available concerning these matters. There are pros and cons to nearly any combination in the recording chain, and the reasoning behind the discussions may pry open the doors of your imagination for future projects. Happy trails to you!!! slight aside: Equalization and compression can be useful before committing your captured sound to the recording medium, but anything that modifies the source sound may be difficult to undo at a later stage if you regret it then. And, as mentioned, microphones, cables, and pre-amplifiers all have an influence on the original air pressure waves similar to a slight equalization and compression. We will get into these subjects in the topic called “Mix”.
Record 15 Recording medium From the earliest mechanical systems - cylinders, wire recorders, waxed surfaces, etc. - up to the state of the art technology of today, there have been very many approaches to fixing the captured airwaves on to a re-playable medium. To look into even half of them would be a truly daunting task, but to keep in mind their objective, and their relative strong points, would provide guidelines for building one’s own recording arsenal. The two most obvious types of medium now seem to be analog (analogous) and digital (based upon zeros and ones). Like two families, there are several members in each. In the analog family we would think primarily of tape in the form of cassettes or reels and in the digital family we could think of optical discs, DAT tapes, hard drives in the computer, or data cards in camera recording devices. Analog recording implies a captured signal that is analogous to the source, but this does not mean that a continuous line, no matter how wiggly - Wave Forms - should be represented on the medium by a similar wiggly continuous line. On vinyl records that seems to be the case, but sound captured on tape does not look like this.
Record 16 Ideal, or perfect recording situations are rare, and we can assume there will be some loss in finer details (frequency response or dynamics), but the overall final capture should closely represent the sound pressure levels that hit the microphone’s diaphragm. Assuming that your microphone to medium chain had little loss, what can we expect from our analog recording medium? As an example, let’s briefly look at a typical, good reel to reel tape recorder. The interplay of electricity and magnetism is at the heart of the process; an electrical current in a conductor creates lines of magnetic force. Relative movement between a conductor in a circuit and a magnetic field can transfer (transduce) information. This allows the electrical representation in the cable - coming from the microphone - to be set in a magnetic medium. This also allows - by the tape passing over the play head of the recorder - the magnetically stored information to be transduced into an electrical signal destined to feed an amplifier - in a stereo system, for instance.The electrical information going to the tape will modify the tiny magnetically sensitive needleshaped particles on its surface so that the newly recorded position they take
Record 17 will store an analog representation of the sound pressure level variations first captured by the microphone and then carried as electrical current to the tape recorder. Leaving aside all complications such as bias, azimuth, wow and flutter, etc., just think of particles on the tape surface waiting for the flux. The strength of the signal determines the influence on the particles, and physical limits can be reached depending upon the quality of the tape. If you decide to push the level going onto the tape, it could result in an unpleasing distortion, or you could profit by a softer saturation, a sort of natural sounding dynamic compression due to the inertia of the particles bonded to the base (cellulose acetate, PVC, polyester, etc.). This is one of the very important benefits of recording to tape that has been known to engineers for a long time. It is also one of the reasons that certain sound sources (voice, bass, kick drum, etc.) are still preferably captured first to tape whatever may be the subsequent steps in the musical project. It should be mentioned, although obvious, that the tape medium is much more difficult for editing, due to the winding times and the necessity of cutting and splicing with precision when removing
Record 18 or adding sections. Another caveat concerning high quality tape recorders is the importance of professional maintenance of the transport, head alignment, bias, etc. Digital medium Digital - in this case based upon the distinction between zero and one as information - is very prevalent in our lives now: CDs and DVDs, data in computers etc. Its robust and lasting quality is that a zero is almost never confused with a one, no matter whether it is a series of pits on a CD or a positive or negative electrical measure. It is or it isn’t: it’s the ultimate “To be or not to be!” - although quantum computers will kick their butts one day! Digital encoding by nature is different from the analogue squiggly line; in fact when seen in a graphical representation, it resembles a staircase. The on-off nature of the zeros and ones seems more akin to a pulse wave - “Waveform” - than to a sine wave. It seems perhaps far removed from the waves on a pond image used to describe spreading soundwaves, but in fact recent medical research seems to point to a sort of final digital, or stepped transmission of sound from our ears to our brains Time.
Record 19 So, how are these stepped representations different from those of an analog medium? If we remember that you can saturate tape in a natural process and come up with pleasing sound, you have to think differently with digital sound. Digital representation is a slicing up of a continuous signal at regular intervals controlled by the sampling frequency, each slice becoming a measure, and the points from these measures being joined by straight horizontal or vertical lines, resulting in a staircase view that would have pleased Escher. Again, the details of this process are intense and we won’t get into them here, but look up Shannon, Nyquist, or Bell laboratories, on the net, and you will find very in depth explanations. Suffice it to say that if you increase the frequency of your slicing - like more teeth on a comb - you get more points of measured intensity, and get closer to the shape of the analog wiggly line. This will improve the results in the frequency range if properly implemented - taking into account jitter and other problems. A basic guideline is that the sampling frequency must be at least two times the highest frequency you hope to capture (in an ideal, mathematical world), but there is much more to it than that.
Record 20 So, we’ve digitally described the frequency of the sound, but what about the dynamics? Those famous ppps and FFFs have to be represented, and in digital recording, the number of bits is how we map out the distinct step-like dynamic levels. The number of bits used for a CD recording is 16, and can theoretically give us up to 96 dB between silence and the loudest signal. Many people prefer to work with 24 bit audio for more head room, and software mixers and effects algorithms use even more bits to allow for as much headroom as possible to avoid going over, or clipping. This is the Achilles’ heel of digital: clipping, where a wrap around effect happens, a phenomenon that offers our ears the equivalent of thousands of fingernails being clipped at the same time while hundreds of others scratch broken glass! Does Digital have advantages over analog? The vast debate, indeed. If you compare a Lamborghini and a hot dog, each has its merits, but the debate will be rather sterile. Suffice it to say that almost anyone reading this will at one point or another be hard-pressed to distinguish the difference between sounds recorded in analog, or digital, or in a mix of the two. Good quality ears
Record 21 and astute listening can bring your production in any medium to worthwhile results. Digital medium is omni-present these days and has the possibility of identical copies, and instant movement from one point in the song to another for editing. A poorly designed digital recording chain will not necessarily be better or worse than a mediocre analog system! Learning to navigate in both the analog and digital worlds may bring you closer to the waters where that whopper awaits your bait!! Happy fishing!!!
P.S. Don’t forget the bait!!!
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