coaxial cable

A single copper conductor, surrounded with a heavy layer of insulation, covered by a thick surrounding copper shield and jacket. A constant-impedance unbalanced transmission line.

CobraNet™

A trademark of Peak Audio identifying their licensed networking technology used for the deterministic and isochronous transmission of digital audio, video, and control signals over 10 Mbit and 100 Mbit Ethernet networks.

codec (code-decode also compression-decompression)

Originally a device for converting voice signals from analog to digital for use in digital transmission schemes, normally telephone based, and then converting them back again. Broaden now to mean an electronic device that converts analog signals, such as video and voice signals, into digital form and compresses them to conserve bandwidth. Most codecs employ proprietary coding algorithms for data compression, common examples being Dolby's AC-2, ADPCM, and MPEG schemes. It is data compression (and direct digital video & audio inputs) that has evolved the newer meaning of compression-decompression.

combining response

Common Time

This is the ordinary name and reference for the time-signature 4/4; that is, four beats per measure and one quarter note to the beat. It is called common time because it is used abundantly in Western musical rhythms. The time signature can be indicated as 4/4 or by "C" written in the beginning of the first measure in a score following the key-signature. The C denotes "C"ommon time.

Community Standards

Refers to the standard for determining the artistic value of a creative work in a particular locality, usually a state. When laws allow much smaller communities, such as towns or counties, to implement their own standards, a threat exists that creative works will be denied to everyone because the narrowest view of creativity will prevail. Such laws impede the marketplace and raise serious constitutional issues.

compander

A contraction of compressor-expander. A term referring to dynamic range reduction and expansion performed by first a compressor acting as an encoder, and second by an expander acting as the decoder. Normally used for noise reduction or headroom reasons.

Compilation

A collection of previously released songs sold as a one album unit, or a collection of new material, either by single or multiple performers, sold as a collaborative effort on one musical recording.

Compressor

A signal processing device that does not allow as much fluctuation in the level of the signal above a certain adjustable or fixed level.

Computer Interface

Hardware which enables a computer to communicate with other devices. A common example is a MIDI interface, which allows a computer to communicate with a musical instrument.

Concert Ratings

Proposals that would permit local government officials to rate music concerts and label tickets accordingly, in advance of the performance. The goal would be to regulate the access of minors to concerts and in some cases even prevent certain concerts from being conducted.

condenser microphone

A microphone design where a condenser (the original name for capacitor) is created by stretching a thin diaphragm in front of a metal disc (the backplate). By positioning the two surfaces very close together an electrical capacitor is created whose capacitance varies as a function of sound pressure. Any change in sound pressure causes the diaphragm to move, which changes the distance between the two surfaces. If the capacitor is first given an electrical charge (polarized) then this movement changes the capacitance, and if the charge is fixed, then the backplate voltage varies proportionally to the sound pressure. In order to create the fixed charge, condenser microphones require external voltage (polarizing voltage) to operate. This is normally supplied in the form of phantom power from the microphone preamp or the mixing console.

constant group delay

constant-Q equalizer (also constant-bandwidth

Term applied to graphic and rotary equalizers describing bandwidth behavior as a function of boost/cut levels. Since Q and bandwidth are inverse sides of the same coin, the terms are fully interchangeable. The bandwidth remains constant for all boost/cut levels. For constant-Q designs, the skirts vary directly proportional to boost/cut amounts. Small boost/cut levels produce narrow skirts and large boost/cut levels produce wide skirts.

constant-voltage

The common name given to the general practices begun in the 1920s and 1930s (becoming a U.S. standard in 1949) governing the interface between power amplifiers and loudspeakers used in distributed sound systems. Installations employing ceiling-mounted loudspeakers, such as offices, factories and schools are examples of distributed sound systems. The standard was derived from the need to minimize cost and to simplify the design of complex audio systems. One way to minimize cost is to minimize the use of copper, and one way to do that is to devise a scheme that allows the use of smaller gauge wire than normal 8 ohm loudspeakers require. Borrowing from the cross-country power distribution practices of the electric companies, this was done by using a transformer to step-up the amplifier's output voltage (with a corresponding decrease in output current); use this higher voltage to drive the (now smaller gauge due to smaller current) long lines to the loudspeakers; and then use another transformer to step-down the voltage at each loudspeaker. Clever. This scheme became known as the constant-voltage distribution method. The term "constant-voltage" is quite misleading and causes much confusion until understood. Point 1: In electronics, two terms exist to describe two very different power sources: "constant-current" and "constant-voltage." Constant-current is a power source that supplies a fixed amount of current regardless of the load, so the output voltage varies, but the current remains constant. Constant-voltage is just the opposite. The voltage stays constant regardless of the load, so the output current varies but not the voltage. Applied to distributed sound systems, the term is used to describe the action of the system at full power only. This is the key point in understanding. At full power the voltage on the system will not vary as a function of the number of loudspeakers driven, that is, you may add or remove (subject to the maxi um power limits) any number of loudspeakers and the voltage will remain the same, i.e., constant. Point 2: The other thing that is "constant" is the amplifier's output voltage at rated power -- and it is the same voltage for all power ratings. Several voltages are used, but the most common in the U.S. is 70.7 volts rms. The standard specifies that all power amplifiers put out 70.7 volts at their rated power. So, whether it is a 100 watt, or 500 watt or 10 watt power amplifier, the maximum output voltage of each must be the same (constant) value of 70.7 volts. This particular number came about from the second way this standard reduced costs: Back in the late '40s, UL safety code specified that all voltages above 100 volts peak created a "shock hazard," and subsequently must be placed in conduit. Expensive. Bad. So, working backward from a maximum of 100 volts peak (conduit not required), you get a maximum rms value of 70.7 volts (Vrms = 0.707 Vpeak). [Often "70.7 volts" is shortened to just "70 volts." It's sloppy; it's wrong; but it's common -- accept it.] In Europe, the standard is 100 volts rms (I don't know why, possibly a misreading of the American standard? If you know write me). This allows use of even smaller wire. Some large U.S. installations used as high as 210 volts rms, with wire runs of over one mile! Remember, the higher the voltage the lower the current, and consequently the smaller the cable and the longer the line can be driven without significant line loss. [The reduction in current exceeds the increase in impedance caused by the smaller wire because of the current-squared nature of power.] In some parts of the U.S. safety regulations regarding conduit use became stricter, forcing distributed systems to adopt a 25 volt rms standard. This still saves conduit, but adds a considerable increase in copper cost, so its use is restricted to small installations. Modern constant-voltage amplifiers either integrate the step-up transformer into the same chassis, or employ a high voltage design to directly drive the line without the need for the transformer. Similarly, constant-voltage loudspeakers have the step-down transformers built-in. Both 70.7 volt amplifiers and loudspeakers need only be rated in watts. An amplifier is rated for so many watts output at 70.7 volts, and a loudspeaker is rated for so many watts input (to give a certain SPL). Designing a system becomes a relatively simple matter of selecting speakers requiring so many watts to achieve the target SPL (quieter zones use lower wattage speakers, etc.), and then adding up the total to obtain the amplifier(s) power. For example, say you need (10) 25 watt, (5) 50 watt and (15) 10 watt loudspeakers, then you need at least 650 watts of amplifier power (actually you need about 1.5 times this due to real world losses, but that's another story).

Continuous Controller

Refers to Midi information other than notes. For example, volume, pitch bending, modulation (vibrato). These parameters can change continuously over time and allow electronically generated music to sound more expressive.

Contour

Controller

1) In MIDI, a device that generates a MIDI signal to control synthesizers, sound modules or sample playback units. 2) A remote control unit for a multitrack tape machine which controls transport functions as well as monitor selection switching functions and record ready/safe status of each track. 3) Any device generating a control voltage or signal fed to another device's control input.

Copy

To make a copy of something, either a sound or segment, by selecting it and choosing the copy function from the module menu. What is copied is placed on the clipboard.

Corba (common object request broker architecture)

An ORB (object request broker) standard developed by the OMG (object management group). Corba provides for standard object-oriented interfaces between ORBs, as well as to external applications and application platforms (from Newton's Telecom Dictionary; see Pro Audio Reference Books). Not to be confused with CobraNet.

correlation

A mathematical operation that indicates the degree to which two signals are alike.

CRC (cyclic redundancy check)

An integrity checking process for block data. A CRC character is generated at the transmission end. Its value depends on the hexadecimal value of the number of ones in the data block. The transmitting device calculates the value and appends it to the data block. The receiving end makes a similar calculation and compares its results with the added character. If there is a difference, the recipient requests retransmission.

Crescendo

Indicated by an acute triangle opening to the right above the staff, this notational device instructs the musical performer to begin increasing the volume of their playing. Sometimes crescendos are quite extensive over time from piano to forte building over numerous measures. At other times crescendos are more immediate and performed in a limited number of measures (two or three).

crosstalk

(recording)

crosstalk

(signal) 1. Undesired capacitive, inductive, or conductive coupling from one circuit, part of a circuit, or channel, to another. 2. Any phenomenon by which a signal transmitted on one circuit or channel of a transmission system creates an undesired effect in another circuit or channel. Note: In telecommunications, crosstalk is usually distinguishable as speech or signaling tones.

<< Start < Prev 1 2 3 4 5 6 7 8 9 10 Next > End >>