Editing DI unit (section)

==Passive units==
[[Image:passivedi.jpg|thumb|200px|right|A very simple, inexpensive passive DI]]

[[Image:Radial JDI Mk 3.jpg|thumb|200px|right|A passive DI with "throughput" in addition to XLR output]]
A passive DI unit consists of an audio [[transformer]] used as a [[balun]]. The term "passive" indicates that the unit does not require a power source (such as batteries or phantom power) to operate. The quality of the audio transformer significantly impacts the fidelity and noise suppression capabilities of passive DI boxes. Manufacturers commonly highlight that high-quality transformers are essential for effective, noise-free audio signal transmission.<ref>{{Cite web |title=DI Box: What does & can it do? {{!}} Palmer |url=https://www.palmer-germany.com/en/blog/What-is-a-DI-Box/ |access-date=2025-03-19 |website=Palmer® {{!}} Be true to your sound |language=en}}</ref> This makes passive DIs less expensive, but it also means that they cannot amplify signal power. The turns ratio on a passive DI is typically chosen to convert a [[nominal impedance|nominal]] 50 kΩ signal source (such as the magnetic pickup of an electric guitar or electric bass) to the 100–200 Ω expected by the mic input of an [[audio mixer]]. Typical turns ratios are in the range of 10:1 to 20:1.<ref>[http://www.aes.org/e-lib/browse.cfm?elib=11561 AES E-Library: ''Interfacing Electronics and Transformers'' by Finnern, Thomas]</ref><ref>{{Cite web |url=http://emusician.com/mag/emusic_going_direct/ |title=Electronic Musician, Nov 1, 2001. Scott Wilkinson. ''Going Direct'' |access-date=January 19, 2010 |archive-url=https://web.archive.org/web/20100113153040/http://emusician.com/mag/emusic_going_direct/ |archive-date=January 13, 2010 |url-status=dead }}</ref><ref>{{Cite web|url=https://www.emusician.com/gear/going-direct|title=Going Direct|last=Wilkinson|first=Scott|date=November 1, 2001|website=EMusician|language=en-us|access-date=2019-03-22}}</ref> Less commonly, a passive DI unit may consist of a [[resistor|resistive]] load, with or without [[capacitor]] coupling. Such units are best suited to outputs designed for [[headphone]]s or [[loudspeaker]]s.{{cn|date=September 2023}}

The less expensive passive DI units are more susceptible to hum, and passive units tend to be less versatile than active; however, they require no power source, are simpler to use, and the better units are extremely 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 middle of a live show or recording session.

Some models have no settings or switches, while others can have a [[ground lift]] switch (to avoid [[Ground loop (electricity)|ground loop]] problems or hums), a [[Attenuator (electronics)|pad]] switch (to accommodate different source levels and attenuate too-strong signals) and a passive filter/equalization switch for coloring the sound or tone.