output standard?

dead rat · 8th October 2008, 07:43 PM

hellooo

Do CD players, mp3 players, radios etc. follow some international standard on output voltage level? like 2V rms?

If one such standard exist please lnik to it

TheSeekerr · 9th October 2008, 04:38 AM

Technically, for an output to be "line level", it should be -10dBV as referenced against a 1 volt RMS sine wave, ie. it should be 0.1V RMS or 0.141V peak.

For professional gear, "line level" is nominally +4dBU as referenced against a 0.775 volt RMS sine wave, or 1.228 V RMS.

In practice, very few items of consumer equipment follow this standard, and it's hardly uncommon for professional gear to to ignore it too.

As a result, it's common practice to design input stages to be able to handle up to 5V RMS, just to be sure.

Ghianni · 9th October 2008, 07:34 AM

Well, there is an IEC (International Electrotechnical Commission) standard under "Publication 268-15" which states that the Line output would have a Normal working output voltage of 1.95Vrms (+8 dB ref 0.775Vrms). May be a new revision exists of this Publication.

kevinkr · 9th October 2008, 05:19 PM

Philips/Sony Redbook (supposedly?) stipulates a level of 2Vrms for 0dBFS, and this has become the defacto standard for consumer digital electronics (non portable electronics) in most markets.

Some information (not complete) here: http://en.wikipedia.org/wiki/Red_Book_(audio_CD_standard)

The output voltage is stipulated somewhere in this document, (IIRC) unfortunately I have not been able to find an excerpt on line that actually shows this.

Frank Berry · 9th October 2008, 05:54 PM

Quote:

Originally posted by kevinkr
Philips/Sony Redbook (supposedly?) stipulates a level of 2Vrms for 0dBFS, and this has become the defacto standard for consumer digital electronics (non portable electronics) in most markets.

Some information (not complete) here: http://en.wikipedia.org/wiki/Red_Book_(audio_CD_standard)

The output voltage is stipulated somewhere in this document, (IIRC) unfortunately I have not been able to find an excerpt on line that actually shows this.

This is how I understand the specification as well.
2Vrms is at absolute clipping. Allowing for 13dB to 15dB headroom, that would put the "normal" output voltage somewhere near .4Vrms.

8th October 2008, 07:43 PM	#1
dead rat diyAudio Member Join Date: Sep 2008	output standard? hellooo Do CD players, mp3 players, radios etc. follow some international standard on output voltage level? like 2V rms? If one such standard exist please lnik to it

9th October 2008, 05:19 PM	#4
kevinkr diyAudio Moderator Join Date: Sep 2004 Location: Boston, Massachusetts Blog Entries: 6	Philips/Sony Redbook (supposedly?) stipulates a level of 2Vrms for 0dBFS, and this has become the defacto standard for consumer digital electronics (non portable electronics) in most markets. Some information (not complete) here: http://en.wikipedia.org/wiki/Red_Book_(audio_CD_standard) The output voltage is stipulated somewhere in this document, (IIRC) unfortunately I have not been able to find an excerpt on line that actually shows this. __________________ www.kta-hifi.net

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9th October 2008, 04:38 AM	#2
TheSeekerr diyAudio Member Join Date: Jan 2008	Technically, for an output to be "line level", it should be -10dBV as referenced against a 1 volt RMS sine wave, ie. it should be 0.1V RMS or 0.141V peak. For professional gear, "line level" is nominally +4dBU as referenced against a 0.775 volt RMS sine wave, or 1.228 V RMS. In practice, very few items of consumer equipment follow this standard, and it's hardly uncommon for professional gear to to ignore it too. As a result, it's common practice to design input stages to be able to handle up to 5V RMS, just to be sure.

9th October 2008, 07:34 AM	#3
Ghianni diyAudio Member Join Date: Sep 2005	Well, there is an IEC (International Electrotechnical Commission) standard under "Publication 268-15" which states that the Line output would have a Normal working output voltage of 1.95Vrms (+8 dB ref 0.775Vrms). May be a new revision exists of this Publication.

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