A

AC: Alternating current. Energy that changes potential at a fixed or regulated rate. Both the electricity that powers our lives, and a signal going to a speaker are forms of alternating current.

ACTIVE CROSSOVER: A crossover placed between a preamplifier and multiple power amplifiers to split the frequency spectrum into two or more parts before it is amplified.

ACOUSTICAL ENERGY: Energy created by sound waves.

A/BTest: A listening comparison between two audio sources playing the same program, performed by switching immediately from one to the other. Examples include playing two basses through the same bass amplifier, or playing the same bass through two amplifiers.

AMPERAGE: A unit of electrical current indicating the force with which energy is pushed through a conductor. Measured in amperes, or amps.

AMPERE: Unit of measurement used to determine the quantity of electricity flowing through a circuit.

AMPLIFICATION: a method for increasing the amplitude (or loudness) of electrical signals

AMPLIFIER: An electronic device which generates a high power signal based on the information supplied by a lower powered signal. A perfect amplifier would add or subtract nothing from the original except additional power.

AMPLITUDE: The measurement of the power of a sound or electrical wave.

ANALOG: An electrical signal in which the frequency and level vary in direct relationship to the original acoustical sound waves that created the signal.

ATTACK: The beginning of a note. The first portion of a note’s envelope in which a note rises form silence to its maximum volume.

ATTENUATE: To reduce the volume of a signal.

ATTENUATOR: A control or switch used to adjust the level of a singal.

AUDIO FREQUENCY SPECTRUM: The range of human hearing, commonly accepted as 20 Hz to 20,000 Hz.

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AUDIO SIGNAL: The analog electronic representation of a sound wave.

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B

BAFFLE or BAFFLE BOARD: The board to which speakers are mounted in a speaker cabinet.

BANDWIDTH: A range frequencies described by the lower and upper frequencies in the range - 20Hz-20KHz, e.g.

BASKET: The outside frame of a speaker that supports the cone and the magnet. Also know as the speaker frame.

BASS: Audio frequencies below 500 Hz.

BASS REFLEX: A vented or ported speaker enclosure.

BALANCED LINE: A cable with two conductors surrounded by a shield, in which each conductor is at equal impedance to ground, but at opposite polarity.

BIAMPLIFICATION (BIAMPING): Splitting the signal into two parts - lows and mids/highs - which are then fed to separate power amplifiers and speaker cabinets. An active crossover is required for biamping.

BIAS: Difference of potential applied to a vacuum tube or transistor to establish a reference operating level.

BRIDGING: Combining the outputs of two amplification channels to provide a single, more powerful, channel.

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C

CAPACITANCE: The storing of an electrical charge between two separate conductors.

CAPACITOR: An electronic device that stores energy and releases it as needed. Capacitors are normally rated in microfarads or millionths of a farad.

CHANNEL: A single path of an audio signal. May be mono or stereo.

CHASSIS: The aluminum or metal structure that houses the electronic components of a device.

CHORUS: A special effect in which a signal is delayed by up to 35 milliseconds, then recombined with the original signal, The delay is varied periodically, thereby creating a multiple voice effect.

CLEAN: Free of noise and distortion.

CLIPPING: A distorted signal generated by an amplifier operating beyond its capabilities. Clipping describes the actual cutting off of signal peaks of an electrical signal at the amplifier’s power limit. Clipping can create very unpleasant distortion, and is the most common cause of speaker damage.

COMPLIANCE: The volume of air - measured in cubic feet - that is equal to the compliance of the total suspension of a speaker.

COMPRESSION: The reduction in dynamic range caused by a compressor.

COMPRESSOR: A signal processor that reduces dynamic range by means of automatic volume or gain control.

CONE: The part of a speaker that moves.

CROSSOVER: An electronic device that divides an incoming signal into two or more frequency bands.

CROSSOVER FREQUENCY: The frequency at which a crossover splits the signal, generally accepted to be the point at which both sides are at -3dB.

Cutoff Frequency: Normally defined as the upper or lower frequency at which the output of a device (such as a speaker) has fallen by 3dB from the maximum level obtainable.

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D

DAMPING: The reduction of resonant energy in a speaker, or between a speaker and amplifier.

dB: Abbreviation for Decibel, or 0.1 Bell. Used to measure volume of a signal.

DC: Direct Current. Power derived from a battery or similar source where electrons flow only in one direction.

DC RESISTANCE: The resistance a device to a DC current.

DECIBEL: The unit of audio level measurement. Abbreviated dB.

Note: The decibel scale is logarithmic in nature. An increase of 10 dB represents a doubling of sound output. Doubling the volume of a system equals a 10dB increase in output, and will require 10 times the power.

DIE CAST FRAME: Driver frame or basket that is cast in a mold, usually from aluminum.

DIODE: An electronic device that blocks current flow in one direction, but allows it in another.

DIRECT BOX: A device used for connecting an amplified instrument directly to a mixer mic input. The direct box converts a high-impedance unbalanced audio signal into a low-impedance balanced audio signal.

DIRECT INJECTION (DI): Recording with or sending a signal to the house mixer via a direct box.

DISCRETE CIRCUITRY: The use of separate components such as resistors, capacitors, and diodes instead of ICs (Integrated Circuits) which print these components in microscopic size on a chip.

DISTORTION: Sound that has been changed from the original performance. The three major forms of electronic distortion in audio are clipping distortion, harmonic distortion, and intermodulation distortion.

DMM (Digital Multimeter): A digital meter that “samples” electrical input to give very accurate readings of voltage, current, or ohms.

D.N.A.: Abbreviation for David Nordschow Amplification, manufacturers of the finest bass amplifiers on the planet. Named after our founder,

CEO, ChEng and fearless leader, David Nordschow.

DRIVER: An individual speaker.

Dv: The inside diameter of a vent or port.

DYNAMIC RANGE: The difference between the loudest and softest sounds that can be reproduced by a device or format.

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E

EFFECTS: Interesting sound phenomena created by signal processors, such as reverberation, echo, flanging, chorus, distortion, octaver, etc.

EFFICIENCY: In a loudspeaker, the ratio of acoustic power output to electrical power input.

E-M: The electro-mechanical parameters of a loudspeaker.

ENVELOPE: The rise and fall in volume of one note. The envelope connects successive peaks of the waves comprising a note. Each harmonic in the note might have a different envelope.

EQUALIZATION (EQ): The adjustment of various frequencies to achieve a particular tonal balance, or to attenuate unwanted emphasis in a specific frequency spectrum.

EQUALIZER: A circuit that alters the frequency spectrum of the original signal.

EXCURSION: The total distance a speaker cone can move.

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F

Fb: The resonant (tuned) frequency of a vented box. Expressed in Hertz (Hz).

Fc: The resonant frequency of a sealed box. Expressed in Hertz (Hz).

F3: The frequency at which power is reduced by one half (-3dB). (Hz)

Fp: The free-air resonant frequency of a passive radiator. (Hz)

Fs: The free-air resonant frequency of a driver. (Hz)

FARAD: The basic unit of capacitance. Capacitors are most often measured in microfarads, or millionths of a farad.

FEEDBACK: The return of some portion of an output signal to the system’s input, often resulting in an unwanted squeal.

FLAT RESPONSE: The equal reproduction of the entire operating frequency spectrum with very minor variation, usually expressed as +/-3dB.

FREE AIR RESONANCE: The frequency at which a driver naturally resonates.

FREQUENCY: The number of cycles per second of a sound wave or an audio signal, measured in hertz (Hz). A low frequency sound (ie: 100 Hz) has a low pitch; a high-frequency sound (ie: 10,000 Hz) has a high pitch.

FREQUENCY RESPONSE: The range of frequencies that an audio device will reproduce at an equal level (within a tolerance, such as +/- 3 dB).

FUNDAMENTAL: The lowest frequency in a complex wave.

FUSE: A device that protects other electronic devices by melting and opening the circuit when the system is drawing too much power.

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G

GAIN: Amplification. The ratio, expressed in decibels, between the output voltage and the input voltage, or between the output power and the input power.

GAP: The space between the magnet and the pole piece in a speaker’s motor assembly that houses the voice coil.

GRAPHIC EQUALIZER: An equalizer with a horizontal row of faders. The fader positions form a graphic representation to indicate the frequency adjustments made to the signal.

GROUND: The zero-signal reference point for a system of audio components.

GROUNDING: Connecting pieces of audio equipment to ground.

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H

HARMONIC: An overtone whose frequency is a multiple of the fundamental frequency of a signal.

HARMONIC DISTORTION: Distortion that follows the natural harmonics of the original signal.

HEADROOM: The safety margin, measured in decibels, between the signal level and the maximum undistorted signal level of an amplifier.

HERTZ (Hz): Cycles per second, the unit of frequency measurement.

HIGH FREQUENCY: The highest audible frequencies, over 5,000 Hz.

HIGH PASS FILTER: A filter that passes frequencies above a certain frequency and attenuates frequencies below that same frequency.

HUM: An unwanted low-pitched tone (60Hz and its harmonics - 50Hz in Europe) heard along with the audio signal.

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I

IMPEDANCE: The resistance of a device to the flow of alternating current. Often used to rate the resistance of a speaker’s voice coil.

INTERMODULATION DISTORTION: Distortion created by a device that is not harmonic with the original signal.

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J

JACK: A female connector that receives a male connector (the end of a cord or cable).

K

KEVLAR: Kevlar is very strong strong and light, and able to withstand significant stress. Many speaker cones are made using Kevlar.

KHz: Abbreviation for Kilohertz or thousands of Hertz or cycles.

KILOHERTZ: One thousand cycles per second.

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L

Le: The inductance of a voice coil.

Lv: The length of a vent or port.

LED: light emitting diode.

LED INDICATOR: An indicator that uses one or more light emitting diodes.

LEVEL: Originally, the power of an amplifier in Watts. Now used to describe the degree of intensity of an audio signal, in terms of voltage, power or sound pressure level.

LIMITER: A signal processor that prevents a signal from getting any higher (louder) than a preset level. Often used to prevent the distortion of attack transients or peaks, or to prevent speaker damage.

LINE LEVEL: In balanced professional recording equipment, a signal whose level is approximately 1.23 volts (+4 dBm). In unbalanced equipment (semi-pro recording equipment, e.g.), a signal whose level is
approximately 0.316 volt (-10 dBV).

LOUDSPEAKER: A transducer that converts electrical energy (the audio signal) into acoustic energy (sound waves).

LOW FREQUENCY: The lowest portion of the Bass spectrum, generally regarded as 40Hz to 160Hz.

LOW PASS FILTER: A filter that passes frequencies below a certain frequency and attenuates frequencies above that same frequency.

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M

MAGNET: The device at the back of a speaker that provides a stationary magnetic field to attract or repel the voice coil as the signal passes through it.

MONO, MONOPHONIC: An audio signal with a single channel of information. A monophonic program can be played over one or more loudspeakers.

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N

NEODYMIUM: A rare earth metal with very strong magnetic properties and relatively light weight. Sometimes used for speaker magnets as a means of saving weight.

NOISE: Unwanted sound, such as hiss or hum. Anything you hear from an amplifier that is unwanted.

NOMINAL IMPEDANCE: The impedance rating used to represent the load the speaker will provide to an amplifier.

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O

OCTAVE: The interval between any two frequencies in which the upper frequency is twice the lower frequency. Example: 80Hz is one octave above 40Hz.

OUTPUT: Sends the signal of a device to other devices. For example, a preamplifier can send an output to effects devices, which is then returned to the preamp, or can send an output to an amplifier to drive speakers.

OVERLOAD: The distortion that occurs when an input signal exceeds a system’s maximum input level.

OVERTONE: A frequency component of a complex wave which is higher than the fundamental frequency.

OHM: A unit of electrical resistance equal to that of a conductor in which a current of one ampere is produced by a potential of one volt across its terminals.

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P

PAD: See Attenuator.

PARAMETRIC EQUALIZER: An equalizer that allows control of center frequency, bandwidth to be manipulated, and amount of boost or cut to that bandwidth - the three parameters of tone control.

PARALLEL OPERATION: The connection of two or more power sources of the same output voltage to obtain a higher output current.

PASSIVE CROSSOVER: A crossover placed after the power amplifier to split the frequency spectrum into two or more parts after it has been amplified.

PATCH CORD: A short cable, used for signal routing.

PEAK: On a graph of a sound wave or signal, the highest point in the wave-form. The point of greatest voltage or sound pressure in a cycle.

PEAK TO PEAK: The measured value of a waveform from peak in a positive direction to peak in a negative direction.

PEAK OUTPUT CURRENT: The maximum current value delivered to a load under specified pulsed conditions.

PHANTOM POWER: A DC voltage (usually 12 to 48 volts) used to power condenser microphones, direct boxes and similar devices.

PHASE: The timing of a sound or electrical wave. Phase is measured in degrees, from 0 to 360. 180 degrees would be perfectly out of phase and often causes signal cancellation in lower frequencies.

PHASE CANCELLATION: The cancellation of certain frequency components of a signal that occurs when the signal is combined with its delayed replica. At certain frequencies, the direct and delayed signals are of equal level and opposite polarity (180 degrees out of phase), thereby canceling each other.

PHONE PLUG: A cylindrical connector (usually 1/4″ in diameter) originally designed for telephone switchboards, now used with audio equipment. An unbalanced phone plug has a tip for the hot signal and a sleeve for the shield or ground. A balanced phone plug has a tip for the hot signal, a ring for the return signal, and a sleeve for the shield or ground.

PITCH: The frequency of a note, usually expressed as the fundamental frequency.

PLUG: A male connector that inserts into a jack (a female connector).

POLARITY: The positive or negative direction of an electrical, acoustical, or magnetic force. Two identical signals which are in opposite polarity are 180 degrees out-of-phase with each other at all frequencies.

POLE PIECE: The metal pole attached to the magnet of a speaker’s motor assembly.

PORT: A vent or tube tuned to extend the usable response of a woofer mounted in a speaker cabinet.

POTENTIOMETER: A variable resistor used to attenuate a signal.

POWER AMPLIFIER: An electronic device that amplifies or increases the power level of an input signal to a level sufficient to drive a loudspeaker.

POWER RATING: DC power available at the output terminals of a power source.

PREAMPLIFIER: The first stage of amplification in an audio system that boosts an instrument or mic-level signal to line level. Controls (tone controls, e.g.) are often used to manipulate the sonic character of the input signal before amplification.

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Q

R

RACK: A cabinet used to hold audio equipment that conforms to 19″ width industry standard.

RADIO-FREQUENCY INTERFERENCE (RFI): The presence of radio-frequency electromagnetic waves in an audio component, causing various noises in the audio signal.

RATED OUTPUT CURRENT: The maximum load current a power supply can provide under specified operating conditions.

Re: The DC resistance of a speaker voice coil.

REFLECTED SOUND: Sound waves reflected from one or more surfaces.

RESISTANCE: The opposition by a circuit to the flow of current. Resistance, abbreviated R, is measured in ohms.

RESISTOR: An electronic component that opposes current flow.

RESONANT FREQUENCY: The natural frequency at which a circuit oscillates or a device vibrates.

ROLL-OFF: The attenuation of frequencies above or below a certain point.

ROOT MEAN SQUARED (RMS) VALUE: Method used to calculate continuous average power output of an amplifier. 1) (periodic function) The square root of the average of the square of the value of the function taken throughout one period (IEEE Std 100-1988). 2) For a sine wave, 0.707 x Peak Value.

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S

SAFETY COMPLIANCE: Certification, recognition or approval by safety agencies such as Underwriters Laboratories Inc. (UL/U.S.A.), Canadian Standards Association (CSA), etc.

SAFETY GROUND: A conductive path to earth that is designed to protect persons from electrical shock by shunting away any dangerous currents that might occur due to malfunction or accident.

SEAL TEAM - The D.N.A. SEAL Team is comprised of long-term endrosers and other close friends who can keep their mouths shut about new designs. Because of this trait - and the fact that we really trust their judgement - SEAL Team members assist us with Field Testing for our R&D proejcts.

SEMI-PARAMETRIC EQUALIZER: An equalizer that allows control of center frequency, and amount of boost or cut to the affected frequencies - two parameters of tone control. Does not normally offer control of bandwidth - the third parameter of tone control.

SENSITIVITY: The sound-pressure level that a loudspeaker produces, generally measured at 1 meter when driven with 1 Watt of pink noise.

CAUTION: Read sensitivity figures carefully, as some companies will publish certain figures measured at 2 Watts instead of 1. SERIES WIRING: A circuit where components are wired sequentially, dividing the voltage between them.

SHELVING EQUALIZER: Applies a constant boost or cut above or below a certain frequency so that the shape of the frequency response resembles a shelf.

SHIELD: A conductive enclosure (usually metallic) around one or more signal conductors that is used to keep out electrostatic fields that can cause hum or buzz.

SHORT CIRCUIT: The situation that occurs when there is an alternate path created between the positive and negative portions of a circuit, bypassing some or all of the components of the circuit and preventing operation.

SIGNAL: A varying electrical voltage that represents information, such as a sound.

SIGNAL PATH: The path that a signal travels from the input to the output in a piece of audio equipment.

SIGNAL PROCESSOR: A device that is used to intentionally alter a signal in a controlled way.

SIGNAL-TO-NOISE RATIO: The ratio in decibels between the signal voltage and noise voltage. An audio component with a high signal-to-noise ratio has little background noise accompanying the signal; a component with a low signal-to-noise-ratio is noisy.

SLAVE: A power amplifier that is receiving an output singal from another (Master) amplifier.

SLEW RATE: The maximum rate of change a power supply output can produce when subjected to a large step response or specified step change.

SOUND-PRESSURE LEVEL (SPL): The acoustic pressure of a sound wave, measured in decibels, above the threshold of hearing. Measured in decibels, or dB.

SOUND WAVE: The periodic variations in sound pressure radiating from a sound source.

SPEAKON CONNECTOR: A heavy-duty speaker connector that can lock in place preventing accidental disconnection, and offers a greater and more stable connection surface. This in turn provides a more effective transfer of power from amplifier to loudspeakers, especially over approximately 250W.

SPECTRUM: The output vs. frequency of a sound source, including the fundamental frequency and overtones.

SPIDER: The part of the speaker attached to the junction of the cone and voice coil that keeps the voice coil aligned in the gap and helps suspend the cone.

SPL: Sound Pressure Level.

STANDING WAVE: A waveform that is created by multiple reflections between opposite room surfaces. At certain points along the standing wave, the direct and reflected waves cancel each other; at other points, the waves combine to reinforce each other.

STEREO, STEREOPHONIC: An audio recording or reproduction system with two channels of information, meant to be heard over two or more loudspeakers to give the illusion of sound-source localization or depth.

SUBWOOFER: A speaker or speaker/enclosure system designed to reproduce only bass frequencies.

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T

THERMAL PROTECTION: A protective feature that shuts down a power supply if its internal temperature exceeds a predetermined limit.

THRESHOLD: In a compressor or limiter, the input level above which compression or limiting takes place.

TRANSFORMER: An electronic component containing two magnetically coupled coils of wire. The input signal is transferred magnetically to the output, without a direct connection between the input an output.

TRANSIENT: A relatively high amplitude, rapidly decaying, peak signal level.

TRANSIENT RESPONSE: Response to signals whose amplitudes rise very quickly, such as slapping on a bass.

TROUBLESHOOT: To determine the cause of failure or poor performance of a system, such as a bass ampli

TUBE: shortening of the term Vacuum Tube (an amplifying device that has elements to send and control current through a vacuum in a glass or metal tube).

TUNING FORK: An ancient device that, when struck, resonated at a fixed frequency to assist musicians in tuning their instruments to correct pitch.

TWEAK: To modify with slight adjustments. Example: David Nordschow is a Tweak Freak, who continually modifies his designs to perform better.

TWEETER: A high frequency loudspeaker.

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U

UNBALANCED LINE: An audio cable having one conductor surrounded by a shield that carries the return signal. The shield is at ground potential.

UNDERWRITER LABORATORIES INC. (UL): American association chartered to test and evaluate products, including electronics products.

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V

VALVE: British term for tube.

VOICE COIL: A coil of wire attached to the rear of the speaker cone that works with the magnet to provide a motor to drive the speaker.

VOLTAGE: Electrical pressure that can do work.

VOLTAGE REGULATION: The process of holding the output voltage constant against changes in input voltage and load current expressed as a percent.

VOLT: The basic measurement of electrical pressure in a circuit.

VOLUME: Number of cubic feet, cubic inches, or liters of space in a speaker enclosure.

VOM: Volt-Ohm Meter. An analog meter that reads Voltage, Ohms, and Milliamperes.

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W

WARM UP TIME: The time needed, after turn-on, for a power supply to meet its performance specifications.

WARM-UP: Process of approaching thermal equilibrium after turn on.

WATT (W): Unit of measure of power equal to 1 joule/sec. (W=El)

WATTAGE: The unit of measurement for electrical power.

WAVEFORM: A graph of sound pressure (or voltage) vs. time of a signal. The waveform of pure tone is a sine wave.

WOOFER: A low-frequency loudspeaker.

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X

XLR CONNECTOR: The part number of an ITT Cannon device which is now used to describe a 3-pin professional audio connector.

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Y

Y Cable: A cable used to split a signal in two in order to send it to two places at once. Or, used to send two signals into the same input.

Z

Z: The nominal impedance of a driver.

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