EBF - Efficiency Bandwidth Product (EBP = Fs / Qes). A parameter that helps determine the suitability of a driver for a sealed or ported enclosure. An EBP of less than 50 indicates the driver should be used in a sealed box, 50 - 90 indicates options including band-pass and ported, over 90 indicates the need for a ported enclosure.
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Effect - A condition produced by a device which modifies sonic structures creatively with various processing techniques.

Effect Loop - A signal path which allows an audio processor (like an equalizer) to be switched in and out of the signal path.

Effective Piston Area - Also referred to as SD. The active radiating area of a speaker cone. This includes that part of the surround which displaces sufficient air to produce a measurable acoustic output. Usually measured in square meters or inches.

Efficiency (Amplifiers) - A rating (measured in percentage) that illustrates how effectively an amplifier uses the power supplied to produce an output. It's a ratio of power in verses power out. For example, an amplifier that is 50% efficient would produce 1 watt of output power for every 2 watts (amps x volts) of DC power input. On a 12 volt system, that means it would take 8.33 amps to produce 100 watts. No amp is 100% efficient. All power not used to produce an output is converted to heat.

Efficiency (Speakers) - Also referred to as Sensitivity. A rating (measured in dB) that illustrates how effectively a speakers uses the power supplied to produce an output. As in amplifiers, it's a ratio of power in verses power out. The most accepted standard to determine this rating is measuring the output of the speaker 1 meter away from it, giving it 1 watt of full audio range (pink noise) input.

EL Backlight - Electro-Luminescent illumination for the lighted portion of a liquid crystal display.

Electrolyte - A mixture of diluted sulfuric acid found in standard lead-acid vehicle batteries.

Electrolytic Capacitor - Also referred to as a Stiffening Cap. A polarized capacitor with a negative and a positive terminal that is commonly used for DC power filtration and energy storage.

Enclosure - A common name for a speaker cabinet or box.

Enclosure Volume - The total amount of internal airspace of an enclosure, generally measured in cubic feet. To find the volume of a cube multiply length x width x height in inches, then divide the result by 1728 (the number of inches in a cubic foot) to get the volume in cubic feet. In order for woofers to reach their bass potential, there will be an optimum airspace volume that's needed, so this formula is essential in designing a woofer box.

Equalizer (EQ) - A filter circuit designed to allow adjustment of particular ranges of audio frequencies (equalization). These can be active (powered circuit) or passive, fixed or variable. Most consumer EQs are powered and fall into 2 different categories, Graphic or Parametric. Graphic EQs are the most familiar type. They divide the the audio spectrum into fixed bands of frequencies, from 3 to up to 30 bands. The 30 band model are considered full octave EQs. The Parametric EQs differ by having a variable range of frequencies plus a bandwidth (how wide a range of frequencies) adjustment for each band.

Ergonomics - A term that refers to the ease of use a system provides in normal operational mode with a minimum of motion and thought required.

Error Correction - (See ESP)

ESP (Electronic Shock Protection) - Also referred to as Error Correction. An electronic circuit that stores the data stream from a CD, DVD or MD in a memory buffer. If the laser pick-up mistracks, the buffer allows uninterrupted playback. How great an error it can correct depends on buffer size.

Excursion - The amount of cone travel (or throw) a woofer is capable of. This is limited by the suspension system the driver itself. When the excursion limit is exceeded, the result is either the woofer will bottom out (the voice coil will bang into the back of the magnet structure, usually causing damage to the coil) or it will tear the surround or spider of the woofer's suspension system (click here for Speaker parts diagram).

Extended Pole Piece - Extended pole pieces on the magnet assembly allow for more voice coil travel, encouraging lower Frequency Response and less chance of the coil "bottoming out" (click here for Speaker parts diagram).