d: The speaker system damping factor of a 4th order bandpass cabinet.

D/A (Digital To Analog) Converter: Circuitry that converts a digital (binary) signal into an equivalent analog waveform. In an audio system, this is done so the signal from digital storage media, such as MiniDisc, CD, or Digital Audio Tape, can be handled by analog system components, such as the receiver and speakers. See 1-bit DM Converter.

DAT (Digital Audio Tape): An audio tape format Sony helped develop that uses linear digital encoding to produce audio with the dynamic range and clarity of a CD on a cassette that is 30 percent smaller than a regular audiocassette.

dB (Decibel): Unit of measure of signal strength. A measure of the power ratio of two signals. It is equal to ten times the logarithm of the ratio of the two signals. Higher dB means stronger signal.

DBS (Direct Broadcast Satellite): Sometimes referred to as Direct Broadcast Service. A system that employs an uplink center to transmit signals to a satellite, which in turn feeds the signal directly to a satellite dish antenna at a subscriber's location. DSS is a type of DBS.

DC-type Lens: An automatic-iris lens with internal circuit which receives voltage and a video signal from the camera to adjust the iris.

Demodulator: converts and/or splits a modulated signal into its component parts (e.g. a VHF/UHF demodulator splits television signals into separate audio and video signals). An FM radio is a demodulator in that it receives a broadcast signal and demodulates the audio so it can be heard.

Depth Of Field: The front to back zone in a field of view which is in focus in the televised scene. With a greater depth of field, more of the scene, near to far, is in focus. Increasing the f-stop number increases the depth of field of the lens. Therefore, the lens aperture should be set at the highest f-stop number usable with the available lighting. The better the lighting, the greater the depth of field possible. In other words, the depth of field is the area in front of the camera which remains in focus. The larger the f-number the greater is the depth of field.

Dia: The "piston" diameter of a speaker driver.

Die Casting: Process where molten metal is poured into a mold. Designed to offer greater precision and vibration resistance than parts made of stamped sheet metal. Used for quality turntable platters and speaker frames.

Digital: A signal that levels are represented by binary numbers.

Digital Comb Filter: advanced circuitry that digitally separates the color (chrominance) signal from picture (luminance) signal, for even greater enhancement of fine detail and significantly reduced picture "noise" (distortion).

Digital Intelligent Comb Filter: An advanced comb filter circuitry converts the incoming signal to digital information, analyzes it, and automatically selects the correct comb filter process that will deliver the best picture and the highest resolution with a minimum of dot-crawl interference.

Digital Synthesis Tuner: A radio receiver system that uses digital calculations based on an ultra-precise quartz crystal reference signal, for crisp, clear drift-free station tuning.

DIP (Dual In-line Package): A semiconductor design that consists of two rows of pins.

Direct-drive System: A turntable system using a low speed motor (that turns at 33.3 or 45 rpm) directly coupled to the platter so that the motor shaft is one with the spindle.

Dispersion: (Speakers) A radiation or diffraction of energy (sound waves) from the energy source. For speakers, dispersion is a measured distribution of sound within a listening area. A wide dispersion is better in most cases for even distribution of sound within the listening area (although there are instances where pinpointed, narrow dispersion is beneficial, like in office P.A. systems where there may be feedback).

Distribution Amplifier: A device that accepts a (video) signal and sends it out to a number of independent outputs that are of the same strength as the incoming signal.

DMM (Digital Multi-Meter): A piece of electronics testing equipment that measures electrical qualities of a circuit or component. Most commonly measures resistance (ohms), current (amperes or amps) and voltage (volts).

Dolby HX Pro® Headroom Extension: Circuitry designed and licensed by Dolby Laboratories and used in many Sony tape decks. It can increase the highest sound level in an audio signal that a component can handle without generating distortion, so you can record at higher peak levels. Operating during the recording of a cassette, the Dolby HX professional system monitors the level of the input signals and optimizes the bias level accordingly. The result is a dramatic improvement in the dynamic range of high frequencies.

Dolby Noise Reduction(Dolby B, Dolby C, Dolby S): Circuitry designed and licensed by Dolby Laboratories, used to suppress "noise" (extraneous sound or interference) during recording and playback of audiocassettes. Dolby B and Dolby C both amplify weaker sounds during the recording process, and return them to correct levels during playback to increase dynamic range. Dolby S is the most advanced form. Used in record and playback modes, it can enhance an audiocassette deck's dynamic range to near-CD quality.

Dolby Pro Logic® Surround Decoding: Circuitry available on many home audio receivers that can process the Dolby Surround encoding found on most movie soundtracks and some network TV shows. It involves the playback of 4-direction sound (left, right, center and rear) and steering logic (directional circuitry). When used in conjunction with such equipment as an AV Laser player, a VHS Hi-Fi Stereo VCR, and a surround sound speaker package, it offers the realism and dramatic impact of top quality movie theater sound.

Driver: An individual "speaker" in a loudspeaker system. Also a piece of software or programming that translates information traveling between two or more components in a computer system.

DSP (Digital Signal Processing): The manipulation of an audio signal in the digital domain, to maintain clearer sound with less distortion and noise than with analog processors. Digital signal processors can perform equalizing and crossover functions; automatic sound DSP units can compensate for seating position to deliver optimized sound to each position in a vehicle. DSP units can also create the ambience of different listening environments, such as a concert hall or jazz club.

DSS (Digital Satellite System): A standard format of digital satellite broadcast transmissions.

Dv: The inside diameter of the port tube in a vented cabinet speaker system.

Dwell Time: The length of time a switcher holds on a camera before moving on to the next in sequence.

Dynamic Range: The difference between the softest and loudest sounds contained on an audio source that an audio component can reproduce; measured in decibels (dB). A higher number indicates greater dynamic range.