Talk:DI unit

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Nice article. I've added a high quality picture of a passive DI box designed by Cyril Jones. In line with neutral tone, I won't grumble about the inclusion of the Behringer unit whatever I think of their designs. --DavidP 21:10, 6 July 2006 (UTC)

Like them or no, their low cost and relatively competent design (and/or thievery of competent design, if that's your preferred word for it) has made Behringer a de facto standard, at least for when "I need it quick, cheap & dirty" applies. If you want something better, you generally already know that you want it. -- Jasper Janssen 15:56, 6 November 2007 (UTC)

Contents 1 Reason for using DI boxes 2 Impedance matching 3 Unit Selection section 4 A little on history

[edit] Reason for using DI boxes

Maybe it would be useful to explain the reason for using a DI box intead of just plugging the instrument into the "line in" input on the mixing console, which is far easier. I do this always and never have had problems with the signals, no hum, no nothing. I've never needed a DI box.--200.14.108.1 19:19, 18 July 2007 (UTC)

Something like a keyboard &c will generally make something close enough to a line signal with low impedance to use directly, but a guitar pickup, for example, will have very high impedance and I think fairly high levels. If your mixer isn't designed for it, things can go Horribly Wrong. Typically it seems you'll find the line inputs on the input strip labeled "Inst" or "inst/line" if they can take a direct instrument input. If you want to inject a high-level low-impedance (speaker and/or headphone) signal, you can quite easily send a regular line input into clipping (most mixers operate their opamps at +- 12-18V powersupply or less, which limits the headroom for high-level in considerably) or even damage it in extreme cases, and a clipped output signal will kill your tweeters at any volume above minimal. In addition guitars (and most other instruments) put out unbalanced signals and for long leads back to the mixing board you greatly prefer a balanced run for resistance to RF interference. -- Jasper Janssen 15:56, 6 November 2007 (UTC)

[edit] Impedance matching

They don't do impedance matching, which would make source and load impedances equal. An active DI box does buffering.

A passive DI box uses a transformer to make the impedances like each other, but doesn't make them equal. I don't know what to call this. I called it "impedance transformation" for now. — Omegatron 22:32, 8 December 2006 (UTC)

The term you are probably looking for is "impedance bridging". I've edited the article to reflect this. --Miken2005 00:16, 24 March 2007 (UTC)

Hi. I'm not much of an expert, so hesitate to edit the page, but this article in Sound On Sound seems to contradict the article, re: impedance. "...they function as impedance-matching devices ... The simplest type of DI box comprises little more than an impedance matching transformer with a balanced output."[1] -- Tremolo (talk) 15:58, 16 April 2008 (UTC)

[edit] Unit Selection section

This reads like a "how to". It should be completely rewritten for encyclopedic tone. I could see two sentences covering the whole section. Binksternet (talk) 14:10, 22 March 2008 (UTC)

I noticed this as well and tried to re-write it after reading it for the firs time. Maybe it'll read a little better now, but if not then whatever suggestions are out there, i'll give it a shot. Stang99gtv8 14:25, 24 March 2008 (UTC)

[edit] A little on history

The article on Sgt. Pepper's Lonely Hearts Club Band seems to indicate that DI was invented by Paul McCartney while figuring out interesting things to do with his bass. So 2 questions: 1. Any verifiable proof of this? 2. If so, how to work into article? Lockesdonkey (talk)