DAD
On Compact Discs : The acronym stands for Digital, Analogue, Digital, which means that the recording and mastering where digital but the mixdown was performed on an analogue console.
On interfaces : = Digital > Analogue > Digital, a codec that can both encode and decode a signal from an analogue one into a digital one and back, most digital converters are either decoders or encoders (i.e. DAC or A/DC).

DASH = Digital Audio Stationary Head
A standard for writing a PCM digital audio data using an S-DAT Recorders onto an 1/2" open reel tape, the standard was worked out by Sony and Studer in the early 80's and Studer is the only company that currently manufacture machines that conform to it. This standard has better error correction and detection that consumer systems such as DAT and ADAT and due to the use of a stationary heads rather than rotary ones makes it much less susceptible to dropouts and alignment problems. The original standard specified 24 tracks but Sony later introduced the Double Density DASH which allows for 48 tracks on the same tape.

DDD
On Compact Discs : The acronym stands for Digital, Digital, Digital, which means that the entire recording chain was supposedly digital from Recording, through Mixing and Mastering, this is misleading because this is an informal standard and up until the late 90's most mixing and mastering was done via analogue I/O even though the processing equipment was digital, furthermore many recordings labelled DDD actually had analogue mixdown but onto a digital recorder which people rather liberally interpreted as digital mixing.
On Open Reel Recorders : = Double Density DASH, see : DASH.

Decimal
The representation of number in powers of 10, this is the basis for most (but not all) number systems used by humans in day to day operations for obvious reasons. Notable exceptions are/were the Etruscans who used base5 (Roman numerals are actually Etruscan numerals adapted to the decimal system, hence Roman X (10) is actually 2 Etruscan V's (5) facing each other), Babylonians and Scandinavians prior to the 12th century used base60, hence 60 min to the hour and 360 degrees to a circle. Base60 is very flexible since it is divisible to both base10 and base12 thereby uniting 2 common traditions and retaining the advantages of both, in Scandinavia there were for a time 3 or possibly 4 meanings for the word hundred including 60, 100, 120 and 144, hence references in the Icelandic Sagas to big and small hundreds.

Trading arithmetic in most of the world was usually base12 (and in the packaging world still is to a degree) this is due to the fact you can only divide 10 into itself, 1,2 and 5 while you can divide 12 into itself, 1, 2, 3, 4 and 6, hence preferred by traders, in hundreds base12 becomes even more flexible, computing equipment usually uses base2 (née binary) although computers have been built using base3 (Ternary) and base10 (specialised accounting machines, using binary for decimal calculations gives rounding errors).

Delaware = Delaware registered company
This term is probably unknown to most people outside the USA, but over there some aspects of company and business law are Federal (i.e. the same across all states and commonwealths belonging to the federal superstate), other aspects such as company registrations and tax laws are fully or partially controlled by local governments. The tiny agricultural state of Delaware has by far the most relaxed regulations when it comes to corporate law and hence is popular for registering companies in, even when the actual company is operating elsewhere, USA based investment shells and other companies that trade mostly in paper money are invariably registered there.

Most of the peculiarities of the Delaware registrations are quite similar to what is known as offshore company registrations (i.e.. Cayman Islands, Manx (Mön) and Guernsey etc.) but others are quite novel such as you are allowed to incorporate with paper money (i.e. the declared initial value of a share is arbitrary and needs not have any relation to reality) which is a technique otherwise only seen in pure tax heavens such as the British Virgin Islands. Large number of USA based CE companies are primarily trading and branding companies that have no manufacturing and sometimes even no warehousing facilities of their own, so it makes sense for them to incorporate in Delaware since they thereby pay lower taxes and enjoy other benefits of simplified regulatory structures.

To put things into perspective Delaware has traditionally been the world’s largest tax haven with over 50% of all USA companies being registered there and that figure goes over 60% when you look at the country’s 1000 largest companies, as such it has more tax and money laundering going through there than all of the world’s other tax havens put together.

DI = Direct Injection
The technique of injecting a musical instrument signal directly into a mixer or a recorder, but traditionally a musical instrument was recorded using a microphone. This became a possibility after electro acoustic and later electronic instruments started appearing on the market, but instruments like electric guitars and pianos had transducers built into them to allow them to be electronically amplified.

The Behringer DI20, a typical “swiss army knife” utility active DI box, but in addition to impedance matching it offers signal splitting, switchable gain and ground lift.

Recording consoles usually had microphone preamplifiers built into them that provided enough gain for the pickup of an instrument but expected a signal of much lower impedance than the instrument transducer gave out. This lead to the invention of the DI box which is simply one or more small audio transformers that lower the impedance of the signal to what the microphone input is expecting, or in the case of instruments that only had loudspeaker outputs the DI box would feature a resistive load on the transformer input as well.

The original DI boxes put out either balanced or unbalanced signals depending on need but the balanced variants became commercially more successful as people found other uses for them such as converting unbalanced signals to a balanced signal for use in live situations but they suffer much less noise with long cable runs than unbalanced ones, DI boxes equipped with an earth lift originally intended to help with noise prone simple single coil magnetic transducers also became popular as a tool to prevent earth loops in large installations or live sets.

The widened usage of direct boxes has meant that there are now almost endless variations of them available on the market, the “active” DI box is a tool that uses an electronic buffer amp to match the impedance rather than a passive transformer, the advantage of that is that it can also amplify the signal and thus not only output a microphone level signals but potentially line level signals and the more advanced active boxes feature variable input impedance and other features not available with a simple transformer. Some DI boxes have also gained features that have nothing to do with the technique of direct injection but are useful in other situations such as live or PA systems, these include split or merge features that allow more than one output from a single input or vice versa. Other features often found in modern DI boxes include “speaker simulation”, but guitar amplifiers invariably use open baffle enclosures that work as a filter on the signal, this is simulated in DI boxes by using a simple resistor network or in some modern variants by using digital technology to model an amplifier.

Since the gain requirements of the transducers used in microphones and in musical instruments are basically the same it is becoming more common to find Microphone amplifiers that either offer a switchable DI mode or automatically allow high impedance signals to enable them to be used as an instrument preamplifier. Note also that while most DI boxes on the market are passive (i.e. use a transformer), ones with a resistive load that can handle signals from a speaker or headphone output are getting rare, most active DI boxes however can handle speaker outputs by default.

The term comes from the recording industry and DI was always “direct injection” in classical studio literature, however more recently people have started to use “direct input” and “direct interface” to avoid confusion with the automotive term and because they feel it describes DI boxes better but note that these terms are not as flexible as direct injection when it comes to writing about the technique rather than the box.

Digital electronics defeat
Digital audio equipment that features analogue audio electronics in the device such as A/DC or or hybrid digital/analogue devices such as modern home theatre amplifiers often offer a defeat function for parts of the digital processing and the display electronics.

The reason for this is that these parts in particular high frequency CPU’s, DSP ‘s and displays modulate signal passing through the analogue electronics via electric or radio interference, this affects low level signal gainstages in particular but can affect other analogue stages as well. The defeat feature is most useful in low end devices since they are invariably only externally shielded for cost reasons, high end equipment usually shields the most sensitive analogue portions of the signal path from internal as well as external interference and the top end devices usually have a completely separate analogue section internally with its own power supply that is mechanically and electronically separate from the digital section. But as with most things this sort of feature annoyingly enough mostly shows up on high end gear. The defeat feature is usually intelligent, so that for instance if you choose to defeat the display it is only off during play and operational in between.

Digital Synthesiser
A type of electronic musical instrument that creates sounds out of component structures and has the signal path totally digital, the instrument can be constructed out of analogue or digital electronics, although it is usually a wholly digital or a hybrid of both technologies, the opposite term is analogue synthesiser.

DIN = Deutsches Institut für Normung
In General : The German industrial standards body, more influential than the size of Germany might suggest and often has developed standards were no others really exist or were existing informal or international standards are not exact enough, many of those have since become ISO standards and others have become de-facto even though they have been rejected or ignored by international or national bodies. Note, this is an industry association and not owned or operated by the government like many think. In connectors : A round multipin connectors, the most often seen variant in audioland is the 5 pin one, superior as an interconnect to the more commonly used Cinch/RCA variant since it carries earth in addition to the signal.
Homepage: http://www.din.de

DIY = Do It Yourself
The manufacture or modification of equipment done by the end user rather than a specialist or a concern, typically done using soldering irons and power tools by the sort of people that you would not give a matchbox to except under duress.

Disk Megabyte
Any multiple of bytes done by someone that does not understand the difference between binary and Decimal, usually the marketing department of any given company or a Wikipedia editor. The bytes are multiplied in 1000's rather than 1024's so a Megabyte becomes 1000000 rather than 1048576 bits, and so on and so forth. In some highly competitive markets this has become the norm since a device with 8,6 GB's does look better from a marketing standpoint than plain 8 GB, hard drive manufacturers being the most notable offenders.

Dither
A technique were noise is injected into an signal to enhance it, mostly useful in intermediate stages of a DAC were it is used to mildly modulate the otherwise squareish signals, but can be used in anywhere in a signal path. In PCM based systems the dithering threshold lies above 24 bits, ergo, all currently available PCM based digital audio equipment theoretically or practically improves with the injection of noise. Note that dither should only be applied once per signal path.

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