A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z  


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

DC Resistance

The resistance a device produces for a DC current. Direct measurement by a digital multimeter or a volt/ohm meter gives DC resistance.


Digital Multimeter. A digital meter that "samples" electrical input to give very accurate readings of voltage, current, or ohms.


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


A measurement of sound pressure, or relative intensity of sound. It should be noted that decibels are logarithmic in nature. An increase of 10dB from a certain point represents a doubling of sound output. From an audio standpoint, doubling the sound output of a system will require 10 times the power.


The usable piston diameter of a driver.

Diamond Pattern Surround

A patented method that JBL uses to control high-frequency resonances in single-piece titanium speaker diaphragms.

Die Cast Aluminum Baskets

Driver baskets that are cast from aluminum. Cast baskets are much stronger than stamped steel and allow for tighter production tolerances and precise driver operation under even the most demanding situations.

Differential Input Circuit

A circuit used by JBL amplifiers that re-creates a preamp-level signal from a high-level signal that is of preamp quality. This method produces a signal that is much lower in distortion than the methods commonly used in other amplifiers.


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

Direct Subwoofer Input

Bypasses the subwoofer's internal crossover to allow the connection of Dolby® Digital (AC-3®) or DTS® receivers and processors that already contain their own subwoofer crossover adjustments.

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. Discrete components allow for tighter tolerances, and higher performance (especially in amplifier output stages), are less heat sensitive, and make better-sounding components.


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.


Another name for a speaker.


The inside diameter of a vent or port.

Dynamic Bass Optimization (DBO)

A unique active bass EQ circuit that allows the tuning of a subwoofer enclosure after it has been installed into a vehicle.

Dynamic Range

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