DI: Difference between revisions
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* impedance mismatch | * impedance mismatch | ||
* line level mismatch | * line level mismatch | ||
* differences in wiring or connectors (e.g. Balanced [[XLR]] to Unbalanced 1/4" [[Tip-Sleeve]]) | * differences in wiring or connectors (e.g. Balanced [[XLR]] to Unbalanced 1/4" [[TRS|Tip-Sleeve]]) | ||
* noise - especially "hum" ( | * noise - especially "hum" ([[Ground Loop]]) | ||
''A DI unit or DI box is an electronic device designed for connecting a piece of equipment with an electronic audio output to a standard microphone or line level input. It performs both level and impedance matching to minimise both noise and distortion. DI is variously claimed to stand for direct input, direct injection or direct interface. DI units are extensively used with professional and semi-professional PA systems and in sound recording studios.'' -- [http://en.wikipedia.org/wiki/DI_box Wikipedia] | ''A DI unit or DI box is an electronic device designed for connecting a piece of equipment with an electronic audio output to a standard microphone or line level input. It performs both level and impedance matching to minimise both noise and distortion. DI is variously claimed to stand for direct input, direct injection or direct interface. DI units are extensively used with professional and semi-professional PA systems and in sound recording studios.'' -- [http://en.wikipedia.org/wiki/DI_box Wikipedia] | ||
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More info about DI's | More info about DI's | ||
* http://whirlwindusa.com/support/tech-articles/direct-box-can-be-di-spensible/ | |||
http://www.leonaudio.com.au/active.htm | * http://www.leonaudio.com.au/active.htm | ||
This is an excerpt - follow the link above for the full story. | This is an excerpt - follow the link above for the full story. | ||
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3. Earth isolation. | 3. Earth isolation. | ||
=== Impedance Conversion === | |||
The medium or high impedance of a signal source is converted to a low impedance suitable for feeding down a long multicore to a mixing desk’s microphone input. A low impedance enables long cable runs, with very little quality loss, and also low susceptibility to external electrical interference which can cause hum and buzzes. | The medium or high impedance of a signal source is converted to a low impedance suitable for feeding down a long multicore to a mixing desk’s microphone input. A low impedance enables long cable runs, with very little quality loss, and also low susceptibility to external electrical interference which can cause hum and buzzes. | ||
A D.I. box should provide a high input impedance for connection to a signal source, and a low output impedance for connection to the microphone input of a mixing desk. | A D.I. box should provide a high input impedance for connection to a signal source, and a low output impedance for connection to the microphone input of a mixing desk. | ||
=== Unbalanced To Balanced Conversion === | |||
The unbalanced (2 conductor) wiring of a signal source is converted to the balanced (3 conductor) wiring of a mixing desk’s microphone input. A balanced cable provides good rejection of electrical interference, while an unbalanced cable does not. Active D.I. Boxes are potentially capable of providing excellent unbalanced to balanced conversion, but due to cost restrictions, most are poor performers in this area. D.I. Boxes that incorporate transformers provide excellent unbalanced to balanced conversion. | The unbalanced (2 conductor) wiring of a signal source is converted to the balanced (3 conductor) wiring of a mixing desk’s microphone input. A balanced cable provides good rejection of electrical interference, while an unbalanced cable does not. Active D.I. Boxes are potentially capable of providing excellent unbalanced to balanced conversion, but due to cost restrictions, most are poor performers in this area. D.I. Boxes that incorporate transformers provide excellent unbalanced to balanced conversion. | ||
=== Earth Isolation === | |||
A D.I. Box provides isolation between the earth wiring of a signal source (e.g. musical instrument) and the sound system to which it is being connected. This prevents earth loops from occuring. | A D.I. Box provides isolation between the earth wiring of a signal source (e.g. musical instrument) and the sound system to which it is being connected. This prevents earth loops from occuring. | ||
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[[category:Gear]] | [[category:Gear]] | ||
[[ | [[Category:Instrument]] | ||
[[category:Terminology]] | [[category:Terminology]] | ||