Talk:Line level

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We should clarify that it's not necessarily a difference in level, but a difference in impedances and the amount of power that can be sourced by an output. Line level outputs are not meant to drive loads like headphones. — Omegatron 22:43, 21 November 2006 (UTC)

Section: Overview

The end of the Overview section currently states that the line level output strength on a device is not affected by the source volume setting. Does this need clarification/removal? Almost all of my pro audio equipment which uses line level outputs has a master volume knob which affects the sound leaving the line level output. Does it just refer to the general line strength or something? Lexusperplexus (talk) 14:34, 16 March 2011 (UTC)

Units

I just finished changing all the units in the article. I had looked here in the talk page beforehand, but neglected to flip through the history, which revealed a number of other editors having changed the units in various ways.

To explain my changes, I tried to make the words uniform (i.e. if it says 1 kX for one thing, it shouldn't say 1000 X for another), and beyond that, merely be as faithful as possible to the house style for units (spell out the word of a unit once, use its correct abbreviation thereafter, use a non-breaking space before the unit, uniform significant digits, etc). The WP guidelines are fairly scattered through the help, but a few of the changes are clumped nearby in WP: 'unit' style (and its surrounding sections and pages).

I think having this article's numbers and units clear, correctly wikilinked, and uniform in style is very important to the article's integrity. If there are objections to anything I've done, let's please discuss it! —Joel D. Reid 06:17, 30 May 2007 (UTC)

Sentence adjustment

This sentence: "signals are then typically sent to a device known as a power amplifier, where they are amplified to levels that can drive headphones or loudspeakers, which convert the signals back into sounds that can be heard through the air."

In my opinion, the section "which convert the signals back..." should just be dropped. It's unnecessary and confusing.

Sources for common nominal levels

This bit: "The most common nominal level for consumer audio equipment is −10 dBV, and the most common nominal level for professional equipment is 4 dBu. By convention, nominal levels are always written with an explicit sign symbol. Thus 4 dBu is written as +4 dBu."

Does anyone have a source for this? —Preceding unsigned comment added by 198.137.214.36 (talk) 18:05, 11 June 2009 (UTC)

This does not seem accurate at all. From my own experience, older computer sound cards usually have 1Vrms in/outputs, while newer cards use 2Vrms. Consumer hi-fi equipment can range from anywhere between 150mV to 2V input sensitivity on the LINE or AUX input. Does a standard for these things even exist? Ikkejw (talk) 17:41, 5 November 2013 (UTC)

From what I have seen, 2 VRMS is related to the Redbook CD standard. I assume that CD players use this and not 0.316 VRMS. If so, which devices do use the -10 dBV standard? Can it be measured easily? 2.111.65.33 (talk) 02:12, 9 September 2014 (UTC)

Consumer gear isn't often built to much of a consistent standard. As for the Redbook CD standard, it defines how digital audio is recorded on CDs. It's been a while since I've looked at it (or had access to it) but I don't think it says a word about analog voltage levels - why would it? Jeh (talk) 02:35, 9 September 2014 (UTC)

Redbook CD has nothing to do with line level voltages. CD player output voltages vary greatly.

The original question about -10 and +4 is answered by cracking open any (and I mean any) book on professional audio, such as the Glen Ballou Handbook for Sound Engineers or the Yamaha Sound Reinforcement Handbook or Gary Davis's Sound Reinforcement Handbook. It's common knowledge. Binksternet (talk) 05:01, 9 September 2014 (UTC)

Saying "It's common knowledge." is not an argument. At all. Because frankly for probably most people who have read of/seen line level and now look in Wikipedia for it these values will be unknown. Someone stumbling upon that topic for the first time almost certainly does not have any of these books — they are also not freely available to easily check — so that does not help either.

And really, if ALL content that anybody considers common knowledge were removed from Wikipedia it would be suddenly be damn near useless; especially if you start considering common line levels in audio applications as common knowledge. Have fun with Wikipedia once all groups of experts start applying that reasoning and get delete-happy or articles are simply useless to simple mortals wanting know about a topic without being experts.

Also, the German Wikipedia (https://de.wikipedia.org/wiki/Bezugspegel_(Tontechnik)) does list different levels (though with I could not yet verify those, topic is quite new for me) than the ones given here for the EBU. That is rigt now not mentioned at all. Currently the article makes it sound as if there are 2 levels (consumer/professional) worldwide. As already said, with no authorative reference.89.14.80.112 (talk) 21:38, 27 November 2015 (UTC)

manualshark.org's PDF

I removed both references to manualshark.org's PDF file (used to 'source' the colors used for line in and line out).

The whole PDF is wholly black and white and doesn't make any mention of colors except for microphone in being 'blue' --not light blue mind you-- which still contradicts PC_System_Design_Guide#Color-coding_scheme_for_connectors_and_ports (mic in is not a line in). Olivier Diotte (talk) 06:43, 1 February 2011 (UTC)

See for yourself: http://www.manualshark.org/manualshark/files/28/pdf_27618.pdf Olivier Diotte (talk) 06:45, 1 February 2011 (UTC)

Contradiction: Line In/Line Out Impedance

The article indicates that the impedances of Line In and Line Out should be the same. However it states that one is 100 ohms while the other is 10 Kohms.CountMacula (talk) 10:20, 22 September 2012 (UTC)

The article goes into some detail about how line level connections use what is called a "bridging" connection, in which the output (source) impedance is considerably lower than the input (load) impedance. I can't see where the article indicates or even implies that they should be the same. Can you be more specific as to where this is? We should certainly fix it if it's there... but I think you're misinterpreting. Jeh (talk) 10:56, 22 September 2012 (UTC)

I guess it's possible that I am misinterpreting. I will give a pointer about how you could decide. Most browsers have a feature to search the page being displayed. It may be under an "edit" feature in the file menu or similar. Try that and you will get a search box where you can type in the word you are looking for, such as "impedance", or even a number, such as "100" or "10". Doing that would lead you to the text fragments:

"Line in expects the kind of voltage level and impedance that line out provides."

"A line input has a high impedance of around 10 kΩ"

"The [line out] impedance is around 100 Ω"

CountMacula (talk) 05:46, 29 September 2012 (UTC)

I am well aware of my browser's "text search within page" feature. And I am well aware of that particular part of the article, as I contributed to it.

There is no contradiction; every statement there is true. Line in presents an impedance of 10 kOhms, but is designed to be driven by a source of much lower impedance. The source driving impedance and the load impedance do not have to be the same; this would in fact break the rules of a "bridging connection". This is further described in the text immediately following the "Impedances" heading, and in even more detail in the "impedance bridging" article linked from there. Jeh (talk) 07:53, 29 September 2012 (UTC)

Thank you for that explanation. It seems that you can tolerate a little leg pulling. But now may I ask you to to change something about the article to eliminate what hung me up? I don't think it is practical to leave it as it is, that is if the purpose is to efficiently impart understanding to someone such as me who does not already understand.CountMacula (talk) 09:53, 29 September 2012 (UTC)

voltage on differential lines.

The article mentions that pro lines are usually differential and then it says that the level is x dbu... OK. So are you measuring each phase with respect to ground or a load placed between the two phases? I tried to find this information elsewhere but I haven't yet succeeded. — Preceding unsigned comment added by 108.28.74.221 (talk) 16:01, 20 March 2013 (UTC)

You measure between the two "phases". — Preceding unsigned comment added by 68.198.133.72 (talk) 21:06, 18 July 2014 (UTC)

Nominal Levels: Approximate?

If 1.736 volts is "approximate", why is it given as four significant figures, down to millivolt precision? 24.85.131.247 (talk) 05:35, 3 August 2013 (UTC)

Agreed. On the face of it either the "approximate" heading, or the figures under it, look silly. Jeh (talk) 00:54, 7 September 2013 (UTC)

The true value is an irrational number derived from a square root equation. Any decimal representation is going to be approximate. Ke6jjj (talk) 20:17, 12 August 2015 (UTC)

Line out - Headphone outputs ?

I wonder about this sentence "Conversely, a headphone output generally has an impedance of only a few ohms (to provide a bridging connection with 32 ohm headphones) and will easily drive a line input."

That would be true of the headphone output on an iPhone ( 7 ohms) but the standard for a receiver or integrated amp headphone jack is 120 ohms and the majority of manufacturers stick to that. A number of dedicated headphone amplifiers have come onto the market that have an impedance close to 0 but they represent (at this time) a niche market. — Preceding unsigned comment added by 202.177.218.75 (talk) 01:33, 27 November 2013 (UTC)

The 120 ohm output standard is bizarre and no one's provided any justification for it that I've seen. Transducers should be driven with as low an impedance as possible, for optimal distortion and frequency response:

• Headphone_amplifier#Output_Impedance
• The Sonic Advantages of Low-Impedance Headphone Amplifiers
• The IEC 61938 standard goes even further in recommending an output resistance of 120 ohms, noting that "For most types of headphones, the source impedance has very little effect on the performance." Whoever wrote that must live in a fantasy world. Many of the headphones currently available in the hi-fi market have a medium nominal impedance of 30–60 ohms and typically display a quite wide variation of impedance with frequency. 3 4
• Headphone Impedance Explained — Preceding unsigned comment added by 68.198.133.72 (talk) 21:02, 18 July 2014 (UTC)

Line out - volume

The section on the line out input states: "The signal out or line out remains at a constant level, regardless of the current setting of the volume control." This may be true for professional audio, or other equipment, but on PC's (which is the experience that the vast majority of the public will have with "line out"), this is clearly untrue. Maybe its incorrectly used, but those symbols, and the term "line out", refer to an output on the PC that speakers are connected to, which is very much controllable volumewise. Again, this may be misusing the term, but since everyone (or at least, that vast majority of the public) does it, surely that should be mentioned in the article? Benboy00 (talk) 02:57, 8 December 2013 (UTC)

 Done. Okay, I fixed those bits through simple deletion. There are many configurations of volume, and such global statements as you identified. cannot always be true. Thanks for the note! Binksternet (talk) 04:39, 8 December 2013 (UTC)

Very old discussion as this is, it seems this related to consumer equipment with built in amplification (like an all in one stereo system, boombox etc) with the Volume control for the integral amplifier, in which the line outs are not controlled by that Volume control. 82.71.30.178 (talk) 20:26, 24 June 2020 (UTC)