A IN unit (direct input) is an electronic device normally used in recording studio and in sound amplifier system to connect high output impedance, channel level, unbalanced output signal to low impedance, microphone level, balanced input , usually through XLR connectors and XLR cables. DIs are often used to connect an electric guitar or an electric bass to the mixed console microphone input jack. DI performs level matching, balancing, and either active buffer or passive impedance/impedance impedance matching to minimize disturbance, distortion, and unwanted ground rotation. The DI unit is usually a metal box with input and output jacks and, for more expensive units, ground lift and switch attenuators.
DI boxes are widely used with professional and semi-professional PA systems, professional sound reinforcement systems and in voice recording studios. Manufacturers produce various units, ranging from cheap, basic, passive units to expensive, sophisticated, and active units. The DI box can provide many features and options that a user can control (for example, a user-selectable 0dB, 20dB or 40dB board and/or "ground lifting" switch). They may come in different types of enclosures, usually metal chassis that help protect against electrical interference. Some bass amplifiers have a built-in DI unit, so the bass amp output signal can be connected directly to the mixing board in sound reinforcement/live broadcast or recording context.
Video DI unit
Terminology
The DI unit is also referred to as a box DI , direct box , or just DI , with every letter spoken, as in "Dee Eye." many are claimed to stand for direct input, direct injection, direct inductions, or direct interfaces.
Maps DI unit
History
The first direct passive box appeared in the United States in the mid-1960s, especially in Detroit on radio and recording stations such as "Motown", "United Sound Systems", "Golden World Records", Tera Shirma Studios, and Metro-Audio Capstan. Roll long distance truck recording. These DIs are specially made by engineers like Ed Wolfrum with his "Wolfbox" and by concert sound companies to solve specific problems related to the strengthening of electric musical instruments, especially electric guitars. These boxes usually contain an audio transformer (such as Triad A11J through 1974) with a rotation ratio of about 8: 1 to 12: 1, and thus an impedance ratio of about 144: 1. With this type of transformer, the instrument's output voltage is lowered to that range compatible with typical mixing microphone console preamp. The typical preamp console input impedance of 1,500 ohms will appear to the electronic instrument as a high input impedance of 216,000 ohms.
Passive boxes are suitable for most electronic instruments but negatively color the sound of people with weaker output signals, such as Fender Rhodes and Fender Precision Basses pianos with single-coil pickups. To accommodate these instruments, the live direct box is designed using powerful electronic circuits that increase input impedance from about 200,000 to above 1,000,000 ohms. In 1975, an active 48-volt phantom active box was designed for Leon Russell's recording studio, a circuit published in dB , a sound engineering magazine. The sound company Tycobrahe, known for supporting large rock festivals such as California Jam, offers an active live box for sale in 1977, a model capable of producing a 9 dBm output level, with built-in attenuator to compensate for various input levels.
Destination
Direct box takes high impedance, unbalanced signal and converts it into low impedance, balanced signal. This allows signals to be transmitted over long running cables with far fewer signal losses (especially in high frequencies) due to lower impedance, and greater interference rejection due to common mode rejection benefits in balanced signals. Furthermore, a lower impedance (about 600 ohm is normal) allows an insignificant load to the input of the mixing console or preamp which is also designed to receive input from a low impedance microphone.
Since all cables used in live sound and recording are "capacitive", long cables used without DI boxes can be "low-pass filters" that reduce high end frequencies. Using the DI box provides a balanced cable, which reduces radio frequency interference and electromagnetic problems coming from the lighting system. Mic wiring is usually a balanced XLR cable; on the other hand, the output of the electric bass or electric guitar is usually a 1/4 "unbalanced cable.Another advantage of DI units is that DI contains"... balancing transformer "which reduces" ground loop problems and potential electrical security problems under conditions disturbance ".
Passive Units
A passive DI unit usually consists of an audio transformer used as a balun. The term "passive" indicates that the unit does not require a battery or other power source to operate. This makes passive DIs cheaper, but it also means that they can not include a preamplifier feature that allows the user to increase the gain. The rotation ratio on passive DI is usually chosen to change nominal 50 k? signal source (such as magnetic pickup from electric guitar or electric bass) to 100-200? expected by the mic input of the audio mixer. Typical rotation ratios are in the range of 10: 1 to 20: 1. Less common, passive IN units can consist of resistive loads, with or without coupling capacitors. Such units are best suited for outputs designed for headphones or speakers.
Cheaper passive DI units are more susceptible to hum, and passive units tend to be less versatile than active. However, they do not require batteries, are easier to use, and better units are very reliable when used as designed. The lack of batteries in passive DIs means that users do not have to worry about batteries losing their power in the midst of live events or recording sessions.
Some models have no settings or switches, while others can have ground lifting switches (to avoid ground loop or hum problems), pad switches (to accommodate different source levels and reduce signal too strong) and passive filters/equalization keys for coloring sounds or tone.
Active unit
Active DI unit contains preamplifier. Active DI units can provide benefits, and are inherently more complex and versatile than passive units. Active IN units require resources, usually provided by a standard AC outlet battery or connection, and may contain options for the use of owl power. Most active DI units provide switches to improve their versatility. This may include strengthening or level adjustment, ground lift, resource selection, and mono or stereo modes. The ground lifting switch often disconnects phantom power. Some active DI units also have electronic securities units.
The pass-through connector is the second jack, sometimes only parallel to the input connector, giving the input signal unchanged, to allow the DI unit to be inserted into the signal path without interrupting. This allows the user, such as an electric bass player, to connect their bass to the DI unit, which directs the bass signal to the mixing board, and at the same time connects the bass to the bass amp onstage for monitoring purposes. Pass-throughs are also commonly referred to as bypass . True-bypass occurs when the signal goes straight from the input jack to the output jack with no circuit involved and no loading source impedance. One bypass (or just 'cut') occurs when the signal is routed through the device circuit with buffering and no other intentional changes to the signal. However, due to the nature of the electrical design there is almost always a slight change in the signal. The extent of the change and how visible it can vary from unit to unit.
Preamplifier
A number of companies make a DI-preamplifier combination for electric bass, double bass, or for acoustic instruments using piezoelectric pickups (eg, Violin, acoustic guitars, mandolins, etc.). These units can be placed in "stompbox" pedal format, in small rackmount units (often less than full rack space), or in units designed to be clipped onto a belt or attached to the instrument. These devices are often marketed as preamplifiers, although they also contain DI feature boxes.
The preamplifier for the electric bass usually contains a gain knob, sometimes including overdrive effect units, equalizer buttons and, for some higher end units, multiple channels (eg "clean" channels and "dirty" channels, with the latter containing overdrive effects).
The Preamp-DI unit for double bass and other acoustic instruments often eliminates overdrive features, but adds additional features that help produce good sound and tone for acoustic instruments, such as audio compression effects, phase inverter switches and notch filters (the last two features designed for help reduce unwanted audio input "howl"). Preamp-DIs for acoustic instruments often include two simple channels and mixers, to allow players to use pickup and condenser microphones. Some preamp-DIs provide phantom power, in which case it is necessary to power the condenser microphone. The Preamp-DI unit may have battery power, have an AC power plug, or both.
General app
Direct boxes are usually used with electric instruments or other electronic music devices containing only unbalanced 1/4 "phone output that needs to be connected to XLR inputs from mixing boards.Several direct box sets can be installed in a single housing, used for multiple outputs unbalanced, as for electronic keyboard banks.
Acoustic or electric instruments
The DI box can be used on instruments with electronic circuits and pickups that do not contain balanced XLR output. An example of this application is the electrical keyboard that needs to be connected to the mixing board, either directly or through an audio snake. Another example is acoustic guitar with pickup, electric guitar or bass guitar, or double bass with piezoelectric pickup. These instruments can be plugged into the DI box, and the DI signal will be mixed through the mixing console into the main mix or monitor.
Instrument booster
Some instrument boosters, especially bass amplifiers, contain DI units installed in them, and can be connected directly to the mixing console without the need for an external direct box. This will be a typical arrangement for a bassist who wants to link their instruments through a public address system (PA system) or a sound reinforcement system on live performances, while maintaining the unique sounds of the preamplifier amplifier and the equalizer circuit and special settings. In comparison, if an external DI box is used, with the bassist inserting his/her bass into the DI box and sending signals to their bass amp, the DI box signal will be a direct signal from the bass pickup. With an external DI box approach, sound formation is added to the bass signal on the amplifier (for example, increasing preamplifier, adding overdrive, or adjusting equalization to change tone) will not exist in external DI box signals. Some instrument amplifiers have the ability to turn off the equalizer amplifier (EQ) via a pre-eq/post-eq switch. This can be used if the direct output is "clean" from the desired amplifier, which does not contain the tone formation made by the bassist adjustment of the EQ control.
It is common to use DI and microphone signals in front of the speaker cabinet or combo amp, both in sound settings and direct recording. One method is to connect the bass guitar loudspeaker output level (via pad, to reduce signal) to DI and then run it to one channel from the mixing console, and run the micror guitar speaker's cabinet signal to the other channels of the mixing console. Another method is connecting DI between the guitar and the amplifier. The DI signal and mic'd guitar speakers can then be selectively selected, with DI providing a more direct, present, bright, uneven sound, and microphones provide a more 'live' sound, with instrument amplifiers and speaker enclosure characteristics and some room atmosphere (natural reverb).
Usage examples
Direct input tracking is used on almost all parts of the electric bass on Sgt. Pepper's Lonely Hearts Club Band , most prominently on "Lucy In The Sky With Diamonds", "When I'm Sixty Four", "Lovely Rita", and "A Day in The Life", as well as "Just A Song North "," I Me Mine ", and lead-guitar that introduced" Revolution ". Other obvious examples include Dave Matthews Band "So Much To Say" and "Daydreamer" Adele.
See also
- Re-amp
References
External links
- Schematic for transformer based, signal-through DI Box - suggested scheme Jensen Transformer for DIbox signal-split
- Direct Boxes - 1998 articles by JdB Sound Acoustics provide some technical info on what direct boxes can do
Source of the article : Wikipedia
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