Vocab Wk 1

Pad

An electronic circuit designed to attenuate the output of a device by a given amount. For example, some microphones have so much output that they can overdrive the input stage of many mic preamps. To prevent this, mic designers will include a switchable "_______" on the output stage of the mic, attenuating, or reducing the mic's output by 10 or 20 dB. While many devices have built-in pads, it is also possible to purchase external _______, which plug in to a device's output and reduce its level. A sustainy, "wash" or fill sound, usually used as harmonic background material in a musical arrangement. Arrangers often speak of using a "string pad" during a passage; this would be a section of strings playing long, sustained chords behind the melody. With the advent of samplers and synthesizers, other types of sounds have also become common as _________; just about any sound that can sustain can be used as a _______ these days!

Attenuation

A decrease in the level of a signal is referred to as attenuation. In some cases this is unintentional, as in the _____________ caused by using wire for signal transmission. ____________ (circuits which ____________ a signal) may also be used to lower the level of a signal in an audio system to prevent overload and distortion.

Unity Gain

A device or setting which does not change signal level (amplify or attenuate the signal) is said to be at "__________." Many processors are set up for __________; that is, they can be plugged into a system without changing its overall levels. In practice, ___________ is often a desired setting for maintaining gain staging, and for optimizing operating levels and signal to noise ratios.

Equalizer (EQ, EQing)

Based on the root word, equal, an ____________ is an audio device whose function is to equal out the tonal characteristics of a sound. At least that was the idea back in the days when they were first conceived as a tool used to get flat response in telephone lines and to make up for the deficiencies in audio equipment and acoustic spaces. Nowadays it could more aptly be named an "un_____________" since they are more often used creatively to alter the relative balance of frequencies to produce desired tonal characteristics in sounds. An ____________ has the ability to boost and/or cut the energy (amplitude) in specified frequency ranges by employing one or more filter circuits. There are many different types of ____________s in use today in many widely varying applications, but they fundamentally all do the same thing.

Trim

Found on most mixers, _______ controls provide the initial level setting for each channel's input gain. In most cases, _______ adjusts gain of the microphone preamp, but it may also apply to line level signals. Optimizing this gain stage will make a tremendous difference in the mixers signal to noise ratio and in gain staging later in the signal chain.

Large Diaphragm

Refers to the size of the diaphragm used in a microphone. Any microphone with a diaphragm larger than (and potentially including) 3/4″ is considered to be a _______________ microphone. In general, ________________ microphones tend to have a "big" sound that engineers find especially pleasing where a little more character might be advantageous, such as is the case with most vocals. _________________ are generally more sensitive than small diaphragm or medium diaphragm mics because of the increased surface area. A common myth is that _________________ mics capture more low frequencies than small diaphragm mics. Sometimes their coloration may make it sound like this is the case, but a properly designed small diaphragm mic is more likely to be accurate throughout a wide range of frequencies, whereas the coloration of a large diaphragm mic can tend to enhance certain desirable characteristics in a sound, which sometimes amounts to more apparent bass or low end.

TRS (Tip Ring Sleeve)

This is the descriptively accurate term used to describe 1/4″ (or 1/8″) balanced connectors. A _____ plug can be found at the end of most headphone cords if you want to know what one looks like. They look like a standard 1/4″ plug with an extra section in them. The three sections of the shaft are called the Tip, Ring, and Sleeve (a "standard" 1/4″ connector just has a tip and sleeve). ____ connectors are used wherever it is desired to have two conductors plus a ground (shield) in one plug. Common uses are as a way to connect balanced equipment (where the ______ plug has a positive, negative, and ground connection), or stereo unbalanced equipment (left and right are on the Tip and Ring, with a common ground) like headphones, or as an insert for your mixer or other processor (Tip or Ring is the send with the other being used as the return and again ground is common).

Supercardioid

A polar pattern name used to describe the pickup pattern of some microphones. The _______________ pattern is very similar to, and often confused with, the hypercardioid pattern. The ___________________ pattern is slightly less directional than the hypercardioid pattern, but the rear lobe of sensitivity is also much smaller in the ________________.

Phantom Power

A DC (direct current) voltage, usually 48 volts, applied to pins 2 and 3 referenced to pin 1 of an XLR microphone connector that can be used to power transducers with active electronics. Condenser microphones require a pre amp close to the very high impedance (See WFTD archive "impedance") diaphragm which requires power to operate. Back in the '50's and '60's this power was often provided by a separate power supply that came with the microphone. Later manufacturers began to provide a source for this power at the microphone input to mixers or pre amps. Since the power is carried on the same wires that carry the audio signal, and since most dynamic microphones and other passive devices are not affected by this DC voltage it was known as __________________. The theory was that only devices that needed it would be wired in such a way that they would use it. Nowadays almost all condenser microphones and active direct boxes are able to use _________________ when it is present on a microphone cable. Consequently most mixing board manufacturers include this feature in their products.

Filter

A __________ is an electronic device designed to reduce a signal's energy at a specific frequency. A true ________ always acts as a subtractive device, not adding anything to the signal. In many _________, an amplifier is often incorporated into the circuit, allowing the frequency to be boosted or cut (active _______). ___________ of different frequencies are often combined to create equalizers.

Decibel

A ____________ (named for Alexander Graham Bell) is a tenth of a bel, and is used as an expression of power. Here's where the confusion arises: A ____________ isn't a measure of ANYTHING; it is a ratio of two power levels. Because of the way our ears perceive volume, these ratios follow a logarithmic curve, expressing them as a ___________ keeps things easier to deal with. Here are a few convenient ____________ figures worth remembering: One _____________ is commonly taken as the smallest volume change the human ear can reasonably detect. Doubling the POWER of an amplifier results in a 3 dB increase, which is a "noticeable" volume increase. Doubling the VOLUME of a sound is a 6 dB increase (you may occasionally see 10 dB listed as the "double-volume" figure, 6 dB is the more mathematically correct number). By doing the math, you can see that truly doubling your volume actually requires 4 times the amplifier power! Keep these figures in mind the next time you are comparing the specs of two pieces of equipment...

Passive

A ____________ audio device is one which does not use amplification circuits. By nature of design, _____________ devices do cause a loss in power (insertion loss). Because they do not contain amplifiers, and are "cut-only" or "subtractive" in operation, ____________ devices tend to not add noise or distortion to a signal (although noise may be added in compensating for insertion loss). Typical _____________ devices include direct boxes, splitters, equalizers and crossovers.

Transformer

A _____________ is a device consisting of two or more coils of wire wound on a common core of magnetically permeable material. The number of turns in one coil divided by the number of turns in the other is called the turns ratio. An alternating voltage appearing across one coil will be inducted into the other coil multiplied by the turns ratio. Some _______________ are designed to operate at 60 Hz (see WFTD archive "Hertz") and to handle large amounts of current. They are called power _______________, and are found in almost all electronic equipment to change our 110 volt line voltage to one or more voltages more suitable for operating the device. Audio ________________ are designed to operate at audible frequencies, and are used to step audio voltages up or down to send signals between devices such as microphones, tape recorders, mixers, and all types of other electronic equipment. _____________ are also sometimes used in audio to provide isolation between two audio circuits. Because the two coils of wire never electrically touch one another a _______________ provides a certain amount of isolation that can help prevent ground loops and other problems that can crop up in complex audio systems.

Subwoofer

A _____________ is a specialized loudspeaker dedicated to reproducing extremely low frequencies. Because many "full-range" speakers can't handle frequencies below 45-50Hz, a _____________ can be added that will output the low frequency information normally missing. In a typical 5.1 setup, the ".1" (or "point one") refers to the ____________. The first commercial ____________ was developed in the 1970s, while the first documented use of a _____________ in a pro recording environment was during the mixdown of Steely Dan's Pretzel Logic album. Early ___________ were huge (up to 34 inches), but today, thanks to advances in technology, ___________ with speakers of 8″ or 10″ are available, though the larger the driver, the lower the ___________ typically can go. Today almost all __________________ are active or self-powered via an onboard amplifier.

Dynamic (Microphone)

A _________________ is one in which audio signal is generated by the motion of a conductor within a magnetic field. In most _________________, a very thin, light, diaphragm moves in response to sound pressure. The diaphragm's motion causes a voice coil which is suspended in a magnetic field to move, generating a small electric current. Generally less expensive than condenser mics (although very high quality ________________ can be quite expensive), dynamics feature quite robust construction, can often handle very high SPLs (Sound Pressure Levels), and do not require an external power source to operate. Because of the mechanical nature of their operation, _________________ are commonly less sensitive to transients, and may not reproduce quite the high frequency "detail" other types of mics can produce. _________________ are very common in live applications. In the studio, _______________ are often used to record electric guitar and drums.

Amperage

A measure of electrical current flow, also called amps for short. It literally equates to the number of electrons in a conductor flowing past a certain point in a given amount of time. Without going into an electronics course here, current is "drawn" from a supply of power due to the presence of a voltage being placed across a load. Uh, in English please? A typical electrical outlet is a good example. There is a 120 volt potential there (think of the voltage as "pressure"), but no current flow. Put some type of load across the outlet (like a light bulb) and you now have a complete circuit in which electrical current can flow. Current will flow according to how much resistance there is to the flow. High resistance (impedance) will yield less current flow than low resistance. Amps are a measure of this current flow. A direct short (no resistance) will cause a very large amount of current to flow and, if the supply is capable of delivering enough ___________, the wire will eventually heat up and melt (possibly causing a fire in the process). That's why we have fuses and circuit breakers. They limit current flow by opening (the opposite of shorting) a circuit before this happens. A 15 amp breaker will trip when the load(s) in that circuit try to pull in excess of 15 amps of current.

Cardioid

A microphone polar (pickup) pattern. Characterized by strong sensitivity to audio from the front of the mic, good sensitivity on the sides (at 90 degrees, 6 dB less than the front), and good rejection of sound from the rear, the ___________ pattern can almost be visualized as a "heart-shaped" pattern (hence its name). The ability to reject sound from the rear makes __________ patterns very useful in multi-miking situations, and where it is not desirable to capture a large amount of room ambience. Popular in both studio and live use (where rear rejection cuts down on feedback and ambient noise), __________ mics are used for a very high percentage of microphone applications. Keep in mind that like all non-omnidirectional mics, ___________ mics will exhibit pronounced proximity effect (see WFTD archives, "Proximity Effect").

Figure 8

A microphone polar pattern in which the mic is (nearly) equally sensitive to sounds picked up from front and back, but not sensitive to sounds on the sides. This produces a pattern that looks like a ___________ on paper, where the microphone is at the point of crossover on the 8. The pattern is also known as bi-directional.

Matched Pair

A pair of microphones that have been measured to ensure that they are extremely close or identical in response. Using a _____________ of mics is usually considered ideal for stereo recording applications, as the two mics will respond in equal fashion, without one coloring the sound more than the other.

Ground Loop

A phenomenon that occurs when an audio (or video) system has multiple paths and path lengths to ground. When a ______________ occurs in an audio system it will manifest itself as a hum. The hum occurs at 60 Hz (Hertz) or some multiple of 60 Hz because that is the line frequency of AC (in the US). In video a _____________ can often shows up as rolling bars (sometimes quite faint) in the picture. The severity of the hum will vary depending upon numerous factors; sometimes it can be quite faint, while other times it can be so loud that it overloads an amplifier. __________________ have been a problem since the very early days of connecting audio equipment together and there have been volumes of materials written on how to prevent and solve them. Any time one connects multiple pieces of audio gear together that are each plugged into an electrical outlet and connected to each other via signal cables, and possibly even electrically connected by their cases touching or being in the same rack, the risk of _______________ increases. There are many valid schools of thought on stopping them, some of which we will get in to in the coming months. At the most basic level, however, the only way to prevent or get rid of ________________ is to make sure that all of your equipment has only one path to ground. One way people sometimes accomplish this is to utilize AC plug ground lift adapters (a.k.a. widow-makers) on offending pieces of equipment as determined by troubleshooting the system, but this is considered unsafe and we highly recommend against it.

Out of Phase

A phrase used to characterize two or more signals whose phase relationship with each other is such that when one is at its positive peak the other is at (or near) its negative peak. This is also commonly referred to as being 180 degrees out of phase. Phase is a relative value that is measured in degrees (like angles). 90 degrees out of phase is more out of phase than 80 degrees, but less than 100 degrees. 180 degrees out of phase is completely backwards, which is characterized by one signal's highest peak correlating with another's most negative peak. Most signals are not entirely in phase with each other, and it's just as rare for them to be perfectly (180 degrees) ________________. But people generally say "out of phase" to mean approximately 180 degrees _______________. People also frequently say "_______________" when the more technically correct term to use would be "polarity reversed." Phase implies a time delay, where one signal lags behind another one to some degree. Polarity refers to one signal being "backwards" from another. An example of this would be the "phase" switch on many mic preamps and mixing boards. Generally all this switch does is reverse pins two and three on the XLR connector entering the preamp, thereby reversing the "polarity" of the signal. There is no time delay of the signal. Nevertheless this is often referred to as "________________." A similar thing happens when you reverse the polarity of the speaker leads to one speaker in a two-speaker setup. That speaker is now operating with the opposite polarity of the other. No time delay was introduced, yet we often refer to this as "_________________." This confusion occurs because when viewed on a display like an oscilloscope waveforms that are 180 degrees out of phase with each other will not look any different than two that are polarity reversed. Sonically the difference is generally pretty minute as well. So for all practical purposes the two terms can be used interchangeably. While it is technically true that any two signals not 100% in phase with each other could be referred to by the somewhat generic phrase, "______________," we generally don't use that terminology until the signals approach a 180 degree phase relationship with each other.

Insert

A point in the signal path of a circuit where it is possible to interrupt the signal and "__________" another signal. Most commonly deployed in mixing boards it usually shows up as a patch point on each channel and/or bus output. The purpose is to be able to interrupt a signal in the mixer, bring it outside the mixer for some sort of special processing, and then return the processed signal to the same point from which it left. Common applications include applying compression, gating, or EQ to a particular channel without affecting any other channels or using any extra buses. Sometimes an _________ is called a "patch" or "injection point."

Hypercardioid

A polar pattern name typically used to describe microphone pick up characteristics. _______________ patterns are similar to cardioid patterns in that the primary sensitivity is in the front of the microphone. They differ, however, in that the point of least sensitivity is at the 150 - 160 and 200 - 210 degree positions (as opposed to directly behind the microphone in a cardioid pattern). __________________ microphones are thus considered even more directional than cardioid microphones because they have less sensitivity at their sides and only slightly more directly behind. _________________ microphones are frequently used in situations where a lot of isolation is desired between sound sources.

Combi Jack

A single jack on a device that allows either XLR and 1/4-inch connection. This saves space on the jack panel of the piece of gear, since separate XLR and 1/4″ jacks aren't required. Most ____________ are female, for input connections.

Graphic Equalizer

A type of EQ that is configured to provide a graphic display of the EQ settings. Years ago equalizers were all rotary knob based. When units began to arrive on the scenes that had 15, 30, or even 45 bands (frequencies) they could EQ at once it became difficult to see what was going on at a glance. Looking at a row of 30 knobs to get an overall idea of the EQ curve is pretty difficult. So equalizers that used sliders instead of knobs were developed and quickly won the favor of engineers due to their improved ergonomics. People liked how easy it was to see the overall EQ curve at a glance, but they also just liked using sliders more than knobs (something that we'd already figured out about mixers). The ONLY thing that makes an EQ "graphic" is this configuration of being able to see the curve at a glance. Contrary to popular belief there are _____________s that have the same features as parametric EQ's, including Q controls and sweepable frequencies. Most ____________s, however, only give you control of cutting or boosting a pre-selected set of frequencies at a pre-selected Q.

Parametric Equalizer

A type of equalizer having several "parameters" for control of various filters that can be applied to audio signals. ____________________ are most widely used in situations where very fine control over the audio signal is desired. In order for an equalizer to be parametric it must at least have control over gain, Q, and frequency. In most cases each of these controls are on rotary potentiometers, but there are a few graphic style ______________________ on the market. Some equalizers have selectable frequencies that can be adjusted, but no Q control. These are known as quasi-parametric or sweepable equalizers.

Electret

A type of microphone design, similar to condenser. Basically, there is a permanently charged plate in the mic element. As the diaphragm moves in response to sound pressure, it creates a changing capacitance with the plate. The big advantage to using ______________ (also called back-____________, or occasionally prepolarized condenser) technology is that it does not require an external polarizing voltage (battery or phantom power). In some cases, the microphone includes an impedance changing preamp that requires battery or phantom power, but the ___________ element itself does not require voltage. ______________ mics can lose their charge in high humidity and high temperature environments, so some care should be used in storing and using them. If the ____________ loses charge, the mic's sensitivity will suffer, resulting in an reduced signal to noise ratio.

Ribbon Mic

A type of velocity microphone. A velocity microphone responds to the velocity of air molecules passing it rather than the Sound Pressure Level, which is what most other microphones respond to. In many cases this functional difference isn't important, but it can certainly be an issue on a windy day. Very old ________________ could be destroyed from the air velocity created just by carrying them across a room. A ______________ works by loosely suspending a small element (usually a corrugated strip of metal) in a strong magnetic field. This "___________" is moved by the action of air molecules and when it moves it cuts across the magnetic lines of flux causing a signal to be generated. Naturally _______________ have a figure 8 pick up pattern. You can think of it like a window blind; it is easily moved by wind blowing at it, but usually doesn't move when wind blows across it from left to right. _______________ were the first commercially successful directional microphones.

CMRR (Common Mode Rejection Ratio)

Abbreviation for ____________________________. In balanced lines there is always a positive signal on one cable and a negative or opposite polarity signal on the other. The idea is that anything common to both wires will eventually get canceled at the receiving end (as noted in WFTD Balanced). The degree of cancellation at the receiving end, however, is dependent upon a number of factors relating to the integrity of the circuit involved. __________ is a spec that defines to what degree common signals are canceled at the input of a balanced system.

Aux Return

An aux input used for bringing a signal back into a mixer. ______________ are often used to bring the output of external effects, such as echo, delay, and reverb into a console.

Proximity Effect

An increase in bass or low frequency response when a sound source is close to a microphone. _________________ is distortion caused by the use of ports to create directional polar pickup patterns, so omni-directional mics are not affected. Depending on the mic design, ____________________ may easily result in a boost of up to 16 dB, usually focused below 100 Hz. Vocalists tend to like _________________ since it fattens up their voice, but a constantly varying bass boost can wreak havoc on headroom and carefully set levels! Obviously, if a vocalist is "eating the mic" to get __________________, the Inverse Square Law (WFTD 6/12) tells us that the levels the mic sees are increasing dramatically as well - distortion can easily result, from either mic diaphragm breakup or electronic overload. (You may occasionally see proximity effect referred to as "bass tip-up")

Direct Current (DC)

Basically direct current is the operational antonym for ______________________. The main distinction being that DC flow does not change directions, and in the case of "pure" DC does not vary at all. Direct current is almost always what is used inside of electronic devices to power the various chips and components, but is considered "bad" or harmful in audio signals, especially those going to speakers. This is because DC produces no sound yet uses a lot of power to be reproduced (remember current flow is constant in DC).

Wavelength

Denoted by the Greek lower-case lambda symbol (l), the distance between one peak or crest of a sine wave and the next corresponding peak or crest. The _______________ of any frequency may be found by dividing the speed of sound (approximately 1100 feet (or 34 meters) per second at sea level) by the frequency. Thus the _______________ of a 60hz sine wave would be approximately 18.3 feet. Knowing _______________ of sounds is very important when designing or working with acoustic spaces such as studios, control rooms, and speaker enclosures.

Polar Pattern

Depending on their design and construction, microphones respond to sound coming from different directions with varying degrees of sensitivity. A plot or graph of this response is called a __________________ (sometimes polar response curve). Looking at a mic's _______________ will tell you how directional it is, how well it will reject sound from certain directions, etc. It is important to note that ________________ are frequency dependent. Typically, low frequency response will be almost omnidirectional; the ________________ will be come more directional as frequency rises.

Channel Strip

Due to the layout of most mixers - channels in columns across the face with the functions of each channel arrayed from top to bottom - a channel is sometimes referred to as a ________. Over the years some mixers have been so highly regarded for their sound quality that a market was developed by marrying a ______________ to a power supply and I/O connections for stand alone use. One could plug a mic directly into the channel strip and record directly to a recorder without having to take the big mixer to the location. Even when such a mixer is available the ______________ approach is often used because it is thought that the simpler signal path of the external strip produces a more pure audio signal to record. This is similar to the popular approach of using high quality stand-alone mic preamps as the only device between mics and recorders, with the major difference being that a _____________ has many more capabilities than a simple mic amp. It may have EQ, compression, gates, and more, depending upon the unit. The idea is that it's everything you're likely to need in the signal path to make a great recording. _______________ are so popular these days that they are generally considered to be a separate product category from preamps and other processing.

Alternating Current (AC)

Electrical current flow that reverses direction on a periodic basis. This is the way our normal household electricity works. _______________ the current flow makes it easier for electrical power to be efficiently distributed over vast distances. In the United States our current changes direction at a rate of 60 times per second (60 Hz). Audio signals are also alternating, with the frequencies corresponding to the frequencies of the sounds present.

Balanced

For us ______________ refers to a type of AC electrical signal having two "legs" independent of ground. One is generally considered positive (+) and the other negative (-) in voltage and current flow with respect to ground. Unlike un___________ audio lines there is no "signal" carried in the shield or ground connection unless there is a fault. The main benefit is that any noise that gets induced into the line will be common to both the positive and negative sides and thus canceled when it arrives at its destination, assuming the destination is ______________. This phenomenon is called "Common Mode Rejection" and basically just means that any signals common to both the positive and negative legs of _______________ lines get canceled. This happens because when the receiving device looks at the signal the common noise actually shows up as out of phase with itself, and gets cancelled. Think of it as if the negative (-) signal gets inverted to positive (+) before use, which puts the desired audio signal in phase with the already positive other leg and at the same time causes the undesired common noise to become out of phase with itself. Clear as mud? _____________ lines are generally much better for long cable runs due to their ability to reject induced noises. XLR and TRS type cables are designed to transmit ______________ audio from one ____________ device to another. A standard 1/4-inch guitar cable is an example of an un_________ cable. Another (newer) application of balancing that is becoming popular in audio systems is the idea of ___________ power systems. Fundamentally the concept is the same. There is a positive and negative (with respect to ground) leg of electricity at every electrical outlet. The idea is that the power supply of any devices connected can then reject any noise induced on the AC line and thus will produce cleaner audio.

Pre-Fade Listen (PFL)

In a console, ______________ is a one of several possible means of overriding the normal monitor signal routing for various purposes. _______ generally sends a signal to monitor outputs regardless of the setting of that channel's fader, and simultaneously mutes the other channels. In other words, ______ allows you to solo a channel even if the fader is pulled all the way down. Note that on most consoles, this affects monitors only, and does not interfere with main, tape, or aux outs. In broadcast situations, _______ is often referred to as "cueing".

Voice Coil

In a dynamic loudspeaker the ____________ is a winding of wire around a cylinder that is attached to the main part of a speaker. The _____________ is inserted into the "gap" created between the magnet and pole piece of a speaker magnet assembly and, when current travels through the wire, generates a magnetic field that causes the speaker to move against the permanent magnet. The alternating current in the ______________ causes alternating magnetic fields to form which interact with the permanent magnet to cause the speaker to move back and forth producing sound.

Bus

In audio (not transportation) terms, a _____ is a point in a circuit where many signals are brought together. For example: Most electronic items have a Ground _____ where all of a device's individual ground paths are tied together. In mixers, we have Mix ________es, where multiple channels' signals are brought (or blended) together; Aux _______es, where feeds from channels are brought together to be routed to an external processor or monitor send, etc. In general, the more ______es a mixer has, the more flexible the routing capabilities of that mixer will be.

Distortion

In audio, ____________ is one of those words that is far more generic in meaning than most people realize when they use it. Technically ____________ is ANY deviation in the shape of an audio waveform between two points in a signal path. Given that understanding, just about any audio process (equalization, compression) are all forms of distortion. Some just happen to be (hopefully) good ones. Other kinds of ____________ (harmonic distortion, Aliasing, clipping, crossover ____________) are considered undesirable, though at times they are put to good use and considered a good thing.

Subgroup

In audio, a ___________ is a group of sources (channels, tracks, etc.) that are combined into one bus on a mixer. The term is very closely related to, but not the same as, submix. ____________ are created for a variety of reasons, most of which have to do with convenience. For example, it is very handy (especially when mixing live) to have sets of common sources grouped together into a ______________ so they can all be controlled with one fader. It is common to create drum sub, a keyboard sub, a backing vocal sub, etc.

Amplitude

In physics and electronics _______________ is literally the maximum absolute value of a periodically varying quantity. In layman's terms it is the strength of a signal or sound without regard to its content. ______________ measurements of audio signals generally refer to the signal voltage, which is only one component of what determines power (watts), or the ability to do work. Thus it is important to understand that ______________ alone does not singly determine power (or loudness in audio), but does affect it. In the physical world the ____________ of a sound is measured in dB of SPL (Sound Pressure Level), which again does not define the true sound power or intensity (many people are confused about this), only the sound level at a point in time. We'll cover this in more detail later when we define those words.

Diaphragm

In the audio world, ______________ refers to the component in a microphone that vibrates sympathetically with air disturbances such as sound waves. It is typically a circular shaped very thin piece of mylar or other delicate low mass material that will range from .2 to 2 inches in diameter. When the _______________ in a microphone vibrates it generates an electrical signal often by either moving an attached coil of wire in and out of a magnetic gap (in the case of moving coil microphones) or by changing the distance between it and another electrically charged plate (as in condenser microphones). These electrical impulses are then present at the output of the mic and ready for amplification as an audio signal.

Active

In the world of music technology passive devices are those things that only subtract elements from a signal. An __________ device has its own power and can, if necessary, add to or amplify a signal in some way. _________ devices have the advantage of being less "lossy" in how they take care of signals and can produce better results under the proper circumstances. The disadvantage to most __________ devices is that they usually add some amount of noise and distortion to a signal (op amps always add noise and distortion), and may color the sound in ways some passive devices may not. __________ devices also tend to be more expensive due to the cost of components and because a power supply is required for them to operate.

LED Light Emitting Diode

It is not an acronym. An ________ is an electronic component that glows when current passes through it. ________s are found in all sorts of electronic equipment these days from watches to laser disc players (in fact the laser that reads the disc is usually an ______). The lights that glow on top of your keyboard are almost surely ______s. The numerical readout and meters on your DAT machine are almost surely ______s. _______s do not always produce visible light. Infrared ______s are used in wireless remote control devices as well as things like wireless headphone systems.

Omnidirectional

Literally, from all directions. In audio, microphones are said to be ________________ if they can detect sound equally from all directions. Speakers are _______________ if they radiate sound in all directions equally; this tends to be the case with subwoofers and low frequency drivers. Low frequencies, in general, tend to be _______________, versus high frequencies which tend to "beam" or be very directional.

Line Level

Literally, the average voltage of an electronic audio signal. While technically any voltage over 25 millivolts RMS is considered ___________, in the modern audio world we narrow the scope a bit to the two ___________ references in use today: Balanced "pro" gear runs at around +4 dBm (1.23 volts), while unbalanced "semi-pro" gear operates at approximately .316 volts (-10 dBV). "Pro" and "semi-pro" may be almost meaningless terms anymore, but the two operating levels must still be dealt with. The important thing is to match the levels of the gear you are using so that -10 equipment isn't directly feeding +4 equipment, and vice versa. If you use gear of both levels, there are various level matching devices on the market to properly interface the items.

Impedance

Measured in ohms, _____________ refers to the resistance of a circuit or device to AC (alternating current). Such an AC circuit could be any two audio devices connected together, like a speaker and an amp, passing audio signals. All other things being equal, more power (watts) will flow through a speaker with a low ____________ than one with a high ____________. This will also put a greater strain on the amplifier to try to produce this power. If the _____________ is too low your amp will not be able to handle it and bad things will happen. Most modern electronic audio devices have extremely high input _______________ so they can be driven by very low power outputs. This is one of many reasons why high quality audio equipment can be built so much less expensively these days.

Nominal Level

Nominal implies that something is according to plan, with only insignificant differences. A _____________ implies a "normal" or, perhaps, typical level in equipment. The nominal operating level of a piece of equipment is thought of as the typical signal level with which it operates. Though this is somewhat vague, the phrase often gets generically used in audio to specify a signal level. For example, on equipment with +4 dBu inputs and outputs the nominal operating level is said to be +4 dBu. This level, which is also its zero reference level, is what it is designed to deal with in terms of typical audio program material. There is sufficient headroom above this level to accommodate peaks or loud sections of audio without distortion. When we refer to nominal levels in audio equipment we are generally referring to zero reference levels. The two phrases are often used interchangeably even though "zero reference" is much more precise.

Direct Box

Often abbreviated DI (for direct insertion), a device commonly used to convert high impedance (see WFTD archive Impedance) unbalanced signals from a stage instrument (like a bass or keyboard) into a low impedance balanced signals. This puts the signal at the proper voltage level for the mixer and prevents the instrument from becoming loaded down with too low impedance, which could cause tonal shifts and distortion. It also allows the signal to be transmitted over long lengths of cable. They are always used in live sound to get a signal out of an instrument on stage out to the mixing board, which can be as much as 500 feet away. A simple ______________ consists only of a small transformer, but more sophisticated designs employ electronic gain stages that more closely resemble the input section of a modern instrument amp. They may also have some combination of ground lift switches, equalization switches, level matching switches, isolated line outputs, and more.

Instrument Level

One of four audio signal levels present in studios and live sound systems - the others being mic, line (two flavors), and speaker level. _________________ is the level (or voltage) put out by an instrument such as an electric guitar, an acoustic guitar with a pickup, or an electric bass guitar. There is no standard for _______________; it is assumed to fall between mic level (on the low end) and line level (on the high end), and it can range from a few millivolts for passive or piezo pickups to several volts on instruments with active pickups and built-in preamps.

White Noise

Random noise with equal energy per frequency is called _____________. It tends to sound very bright and "hissy" due to our ears frequency response curve. (Each ascending octave contains twice as many frequencies as the next lower one, so there is a significant "build up" of energy in the higher octaves.)

Pink Noise

Random noise with equal energy per octave. Our ears perceive this as sounding relatively "flat" in frequency response (since ______________ is based on octaves rather than individual frequencies, there is no increase in energy in the high octaves). Because of this, and because Real Time Analyzers (RTA) tend to look at octave or 1/3 octave ranges, _______________ is very useful for measuring the frequency response of audio equipment, as well as for determining room response for sound reinforcement applications.

Telescoping Shield

Refers to a shield configuration in shielded balanced cables. When the cable shield is connected at one end of a cable, but left "floating" or unconnected at the other it is said to be telescoping. A cable's shield does not necessarily have to be connected to ground at both ends in order to provide effective shielding so they are often telescoped in studio wiring to reduce the likelihood of ground loop problems. Which end of a cable's shield gets left floating (the source end or the destination end) is a subject that is debated in the tweaky circles of studio designers, but most people lift it at the source.

Off-Axis

Refers to an audio source that is not directly in front of a transducer, especially a microphone. This results in ___________ coloration; a distortion or change in the frequency response of the reproduced audio signal. Often this coloration is put to good use. For example, many engineers intentionally set up mics on guitar amps so that they are slightly off access to control the amount of high frequencies captured. A microphone will generally produce the "truest" results if it is used on-axis (oriented directly in front of the sound source).

Small Diaphragm

Refers to the size of the diaphragm used in a microphone. While there are no final standards regarding a diaphragm size that defines ________________, most professionals and manufacturers agree that any diaphragm smaller than 5/8″ would be considered a _____________________. Generally speaking, ___________________ microphones tend to do a good job of capturing high frequency content and transients. They will tend to have a bit more "air" to their sound and often have less coloration than medium diaphragm or large diaphragm microphones. Most of this is due to the reduced mass of the smaller diaphragm, which allows it to more closely follow any air disturbances it is subjected to.

Aux Send

Slang for _________________, a circuit pathway (or bus) in a mixing console that supplies an independent mix, which can be routed to an external device such as an effects processor or monitor system. Most modern consoles have several _____________ on each channel so several devices can process the input to any channel or groups of channels

Dynamic Range

The ___________________ of a sound is the ratio of the strongest, or loudest part to the weakest, or softest, part; it is measured in dB (see WFTD archive "Decibel"). AN ORCHESTRA MAY HAVE A ___________________ OF 90 DB, MEANING THE SOFTEST PASSAGES ARE 90 DB LESS POWERFUL THAN THE LOUDEST ONES. ___________________ in audio equipment specifications is often confused with signal-to-noise ratio. Where signal-to-noise ratio is widely considered to be the available range between the normal operating level of a device and its noise floor, the __________________ is the maximum range available, which would imply it is the range from the highest level attainable in a unit down to the noise floor. With analog systems ___________________specs can be a moving target since it is known that in analog devices the onset of distortion is gradual. Defining a "maximum" level amidst onsetting distortion has not really been standardized in our industry, though most consider 1% to 3% distortion to be acceptable for this measurement. That means the __________________ of an analog device can be thought of, unless otherwise specified, as the range between the noise floor and the maximum level attainable without going over 1% to 3% distortion.

Condenser Microphone

The ______________________ is a very simple mechanical system, with almost no moving parts compared to other microphone designs. It is also one of the oldest microphone types, dating back to the early 1900's. It is simply a thin stretched conductive diaphragm held close to a metal disk called a backplate. This arrangement basically produces a capacitor, and is given its electric charge by an external voltage source. This source is often phantom power, but in many cases ____________________ have dedicated power supply units. When sound pressure acts on the diaphragm it vibrates slightly in response to the waveform. This causes the capacitance to vary in a like manner, which causes a variance in its output voltage. This voltage variation is the signal output of the microphone. There are many different types of ___________________, but they are all based on these basic principles

Sound Pressure Level (SPL)

The acoustic volume or loudness of sound, measured in decibels. _____ is a function of a signal's amplitude. Aside from the usual (and justified) warnings about hearing damage from high ______s, it is worth noting that because of the way our ears function, sounds will appear to have a different timbre (or tone) to us at different ______ levels. This is important to keep in mind, especially when mixing in a studio environment. Be sure to check your mixes at a variety of volume levels to ensure that the mix is accurate. The old rule of thumb is that if a mix sounds good at a low ______, it will sound great at higher levels...

Input Impedance

The impedance present at the input of a device. The _____________ affects the signal entering the device coming from a connected external device. Passive ribbon microphones, for example, generally perform best when connected to a preamp with a high _______________.

Mic Level

The level (or voltage) of signal generated by a microphone. Typically around 2 millivolts. Compare this with the two normal line levels (1.23 volts and .316 volts), and it becomes apparent just how much amplification is going on in a microphone preamp, and why it is essential that preamps be of as high quality as possible!

Ohm's Law

The mathematical relationship between voltage, current, and resistance. It is named after Georg Ohm, its founder. ____________ says the current in a conductor is directly proportional to the voltage across it and inversely proportional to its resistance. In layman's terms this means that more voltage will produce more current if resistance stays the same, but higher resistance will cause current to decrease if voltage stays the same. In math this comes out as V = I x R, where V is voltage, I is current, and R is resistance. ______________ is a fundamental building block upon which virtually all understanding of electronics is based.

Capsule

The portion of a microphone that converts acoustic energy to electrical energy. The ___________ usually includes shock mounts, acoustic isolators, protective covers and electronic circuitry in addition to the basic transducer. Also called an element. It's basically the 'heart' of any microphone.

FOH Front Of House

This distinction comes from theater work where ______________ is any part of the theatre in front of the proscenium arch. In concert and PA applications it is generically used to describe anything in the audience area. Specifically the main, or house mixing position is referred to as the _________ position, which is meant to differentiate the main house mixer from the monitor mixer normally located to the side of the stage.

XLR

Trademarked name for circular 3-pin connectors developed by Cannon (now owned by ITT). "______" was originally nothing more than Cannon's part designation for the connector, which meant "X Series," "Latch," and "Rubber." In fact, you'll also sometimes see these connectors referred to as "Cannon" connectors. ______ has since evolved into a generic industry term, and many manufacturers now make this style connector. In audio work, ______ connectors are normally used for transmitting balanced mic and line level signals. Pin 1 of an ________ connector is always ground/shield. The connectors are designed so that pin 1 makes its connection first when inserted in a jack; this ensures that the ground connection is made first, helping prevent pops and thumps in the audio chain. Either pin 2 or pin 3 may be hot (determined by the gear the connector is plugged into), with the remaining pin being cold. To maintain correct polarity in a signal path, it is important to be aware of which pin is hot or cold on all connections, and wire your cables accordingly.

Inverse Square Law

Useful when setting up a microphone or speaker, the __________________ states that, in a free field the intensity of sound drops by 6 dB for each doubling of distance from the source. Now, none of us ever work in a truly free field (no reflective surfaces), but for most applications these numbers are accepted as workable. In real world terms, this means that for each time you double the distance between your sound source and a listener or microphone, the power of the audio drops by 75% - a fairly significant amount! How much is this in terms of volume? Well, it depends on the source you consult, we've seen both 6 dB and 10 dB convincingly listed as doubling or halving the volume (let's just say it's subjective and leave it at that...) - regardless, 6 dB is a very noticeable drop in level! Consider this the next time you place a microphone or speaker: Rather than just cranking up or attenuating the mic preamp or amplifier level for gain control, look at the distance to your source...

AFL (After Fade Listen)

___ is used in mixing boards to override the normal monitoring path in order to monitor a specific signal at a predefined point in the mixer. Unlike PFL (see WFTD archive "Pre-Fade Listen"), the ___ signal by definition is taken after the fader of a channel or group buss such that the level of the fader will affect the level heard in the ___ monitor circuit. ___ is sometimes also taken after the pan pot which also allows the engineer to monitor the signal with the pan position as it is in the mix. ___ is a handy way to monitor a small group of related instruments by themselves with all of their eq, level, and pan information reproduced as it is in the overall mix. An ___ circuit that includes pan information is often called "solo" (see WFTD archive "solo") or "solo in place" depending upon who builds the mixer

Voltage

___________ is an electric charge, or potential, between two points, one being of higher relative __________ than the other is. A 1.5-volt battery has 1.5 volts of differential between the positive and negative end, for example. The unit of __________ is called the "volt," named after Allesandro Volta. ___________ can be thought of metaphorically as a pressure, such as water pressure in plumbing, that is available to initiate action or work. It, however, cannot do any work until a circuit is complete so that current (measured in amperes) can flow.