Dual Voice Coil (DVC): A voice coil with two windings, generally subwoofers. Each voice coil can be connected to a stereo channel, or both voice coils can be wired in parallel or series to a single mono channel. If connecting to stereo channels it is important that each channel have the same audio signal input so that 2 channels have the same output and both voice coils work in unison.

Driver: A loudspeaker unit, consisting of the electromagnetic components of a speaker, typically a magnet and voice coil.

Driver Parameters: The physical properties of a driver that determine it's electrical and acoustical behavior. Also called thiele small parameters. The minimum parameters used in determing speaker enclosures are Fs, Qts, and Vas.

Dust Cap: Part of the speaker that keeps foreign material from falling into the voice coil, which could hinder the speakers's movement and cut short its life.

Dynamic Range: Expressed in decibels, the range of singnal amplitude (from the loudest to the quietest) that can be reproduced effectively by a piece of equipment. With respect tp amplifiers, this range is defined by inherent noise at low levels and by overload distortion at high levels. The higher the number, the better the performance.

EBP: Efficiency Bandwidth Product. A rating that helps a builder determine wheather a driver is suitable for a sealed or ported enclosure. EBP of less than 45 indicates the driver should be used in a sealed, 45 - 65 indicates flexible design options, over 65 indicates best for a ported enclosure. This only gives us a general idea what type of box to use. With actual testing the subs, sometimes EBP does not prove 100% accurate. EBP = Fs/Qes. Efficiency Rating: The loudspeaker parameter that shows the level of sound output when measured at a prescribed distace with a standard level of electrical energy fed into the speaker.

Electronic Crossover: Uses active circuitry to send signals apppropriate drivers. This is more efficient than passive crossovers.

Enclosure: The box that contains the driver(s).

Equalizer: Electronic device used to boost or attenuate certain frequencies.

F3: The roll-off frequency at which the driver's response is down 3dB's from the level of it's mid-band response, sometimes called the cutoff frequency.

Fb: The tuned freuency of a ported box.

Fc or Fcb: The system resonance frequency of a driver in a sealed box. Fs: The frequency of resonanse for a driver in free air.

Farad: The basic unit of capacitance. A capacitor has a value of one farad when it can store one coulomb of charge with one volt across it.

Filter: Any electrical circuit or mechanical device that removes or attenuates energy at certain frequencies.

Flat Response: The faithful reproduction of an audio signal; specifically, the variations in output level of less than 1 dB above or below a median level over the audio spectrum.