Tape Equalization
In tape decks, the best equalization response must be selected according to the type of tape a normal, chrome, or high-bias. In many decks, automatic sensors perform this function, in others, a switch must be set.
Terminal Cup
A plastic cabinet part that contains the terminal connectors that permits the wire from the amplifier to be connected to the speaker. Sometimes these parts contain the Crossover and protection circuitry as well.
THD
Total harmonic distortion is a measure of the how much a given audio device may distort a signal through the introduction of added harmonics or overtones. These figures are usually given as percentages. THD figures below approximately 1% are inaudible to most people. However, distortion is a cumulative phenomenon, so that if a receiver, equalizer, signal processor, crossover, and amplifier are all rated at "no greater than 1%THD", together, they could produce 5%THD, which may well be noticeable in the perceived sound.
Theile/Small Parameters
The work of Neville Theile and Richard Small is considered to have the most impact on the loudspeaker design field. They discovered a method that could predict the frequency response performance, and other characteristics of a loudspeaker system, based on its physical parameters. For details on these parameters see Understanding Theile/Small Parameters.
Three-way (car speaker)
Three-way or triaxial speakers take the separate woofer and tweeter from a two-way design and add a dedicated midrange Driver for enhanced warmth and texture. The extra high-frequency energy also boosts overall Sensitivity.
THX
THX is a set of standards, components and systems are designed to meet in order to comply with the requirements of high quality film sound reproduction. First developed for Lucasfilm by Tomlinson Holmann, with input from George Lucas himself, THX was intended to define a minimum standard of equipment and quality control that theaters would need to meet in order to become 'certified' as THX approved. The idea was to raise the overall quality and consistency of audio in movie theaters. Lucasfilm had the clout to make such a certification mean enough from a marketing point of view, that theaters wanted to support it and be certified. Subsequently, it has been adopted as a standard in hi-fi equipment with many manufacturers licensing and producing certified THX components for home theater systems.
Timbre
The combination of harmonic frequencies in voices or instruments which give them their characteristic quality. Synonyms: 'Quality', 'Sonority', 'Tone Colour'.
TOC (Table Of Contents)
The digital subcode information that identifies a disc, indicates the number of tracks, the starting and ending points of these tracks, and the total running time of the disc. When included, CD Text information is stored in the TOC.
Toroidal Coil
An inductor or transformer whose core consists of a concentrically wound ribbon of magnetic material. Also used to filter noise on a DC supply line.
Trace
The path of conductive material, usually copper, that conveys voltage or current from one point to another on a printed circuit board. Traces add a slight resistance to the circuit.
Transducer
Synonym for Driver, speaker, or any electrical device that converts one type of energy into another. A microphone is a transducer that converts sound to electrical signals. A speaker reverses the process.
Transformer
An electrical inductive device that can be used to provide circuitry isolation, signal coupling, impedance matching, or voltage step-up.
Transients
A non-repeating sound (such as percussion in music) or an abrupt change of voltage. How a speaker handles transients is a good indicator of its performance.
Transistor
An active (commonly three terminal) solid-state device in which a larger output current is obtained by small changes in the input current. Transistors comprise the greater number of active elements within ic's and microprocessors
Travel Presets or Tuning Memory
With this feature the receiver automatically loads it's presets with the strongest available signals. It makes finding stations easier when driving through unfamiliar territory. It also makes loading presets easier when the receiver is first installed, or any time the battery is discharged, or gets disconnected, which often cancels the tuner's preset memory.
Tremolo
1. A fluctuation of amplitude applied to a sound of constant frequency. Often incorrectly used, as in 'tremolo arm' on a guitar which actually produces vibrato. 2. For stringed instruments such as a mandolin, fast up and down strokes of equal strength of the plectrum or index finger on the strings.
Tube (enclosure)
A type of woofer enclosure consisting of a long tube with a woofer at one end, and a port or Passive Radiator at the other. A good low-end reproducer, this design is very compact and generally used in car stereo.
Tunable (port)
A port tube that can be adjusted in length to provide for optimizing, experimentally, the measured low-end response when a speaker enclosure has not been designed for the woofer Driver installed in it.
Tuned (port)
A port opening, radiator, or tube whose size is precisely specified by the overall design of the enclosure and woofer.
Tweeter
Highs are reproduced by the tweeter, a small speaker mounted inside the woofer cones of multidriver 2 and 3 way car speakers and separately in other systems. Cone tweeters are efficient and the most economical. Dome tweeters - the type found in most home speakers - have a wider angle of dispersion and more accurate. Some domes are made of metals like neodymium or titanium that yield extended high frequency response. Others are made of Mylar, or a fine cloth like silk and produce a smoother if not as extended response. Some are made from a combination of materials.
"Two Ohm Stable"
An X-ohm stable amplifier is an amp which is able to continuously power a load of X ohms per channel without encountering difficulties such as overheating or distrotion. Almost all car amplifiers are at least four ohm stable. Some are two ohm stable, which means that you could run a pair of four ohm speakers in parallel, or a single 2 ohm driver on each channel of the amplifier, and each channel of the amp would "see" two ohms. Some amps are referred to as high-current, which is a buzzword which indicates that the amp is able to deliver very large (relatively) amounts of current, which usually means that it is stable at very low load impedances, such as 1/4 or 1/2 of an ohm. Note that the minimum load rating (such as "two ohm stable") is a stereo (per channel) rating. In bridged mode, the total stability is the sum of the individual channels' stability
Two-way (car speaker)
Music's high frequencies are reproduced accurately by two-way, or coaxial, designs. These speakers use a separate tweeter to deliver high frequency reproduction that surpasses that of dual-cone "extended range" models with whizzer cones. This tweeter, usually a cone or a Dome, is either on a post or bridge inside the woofer.
