What is line level audio?

[amdx]

I want to set the output of a oscillator to drive an audio amplifier.

I thought a line input looks for 1vrms, is that a maximum amplitude for a
line input?

I went to google and found the following

""line-level Standard +4 dBu or -10 dBV audio levels.""

So I looked at +4dBu and -10 dBv and found,

""+4 dBu Standard pro audio voltage reference level equal to 1.23 Vrms.""

""-10 dBV Standard voltage reference level for consumer and some pro audio
use, equal to 0.316 Vrms. (Tip: RCA connectors are a good indicator of units
operating at -10 dBV levels.) ""

Seems to be some confusion,

Your input please,

Mike

 

[amdx]

I want to set the output of a oscillator to drive an audio amplifier.

I thought a line input looks for 1vrms, is that a maximum amplitude for a
line input?

I went to google and found the following

""line-level Standard +4 dBu or -10 dBV audio levels.""

So I looked at +4dBu and -10 dBv and found,

""+4 dBu Standard pro audio voltage reference level equal to 1.23 Vrms.""

""-10 dBV Standard voltage reference level for consumer and some pro audio
use, equal to 0.316 Vrms. (Tip: RCA connectors are a good indicator of
units operating at -10 dBV levels.) ""

Seems to be some confusion,

Your input please,

Mike

I just ran a test on the amp, I can put in 5vrms before I get any visible
distortion.
So I guess the answer isn't important for my app. But I would be curious to
see
some discussion.
Mike

 

[Homer J Simpson]

I want to set the output of a oscillator to drive an audio amplifier.

I thought a line input looks for 1vrms, is that a maximum amplitude for a
line input?

Line level is a higher level than speaker level - it means a signal you can
pass to another device. I'd assume it's about 100 mV to 1V but it varies
anyway.

 

[tempus fugit]

Line level is a higher level than speaker level - it means a signal you can
pass to another device. I'd assume it's about 100 mV to 1V but it varies
anyway.

I think you must have mistyped there Homer. Speaker level is more like 10v
and up. Line level is much lower than that. I agree with the 100mV at the
low end, but I've seen CD players with a line out of 2 or 3v. Same ballpark
though. For the OP and anyone else who's interested, this site is awesome:

http://www.sengpielaudio.com/Calculations03.htm

 

[Eeyore]

I want to set the output of a oscillator to drive an audio amplifier.

I thought a line input looks for 1vrms, is that a maximum amplitude for a
line input?

I went to google and found the following

""line-level Standard +4 dBu or -10 dBV audio levels.""

So I looked at +4dBu and -10 dBv and found,

""+4 dBu Standard pro audio voltage reference level equal to 1.23 Vrms.""

""-10 dBV Standard voltage reference level for consumer and some pro audio
use, equal to 0.316 Vrms. (Tip: RCA connectors are a good indicator of units
operating at -10 dBV levels.) ""

Seems to be some confusion

Not really. There's only 12dB difference ( 4x ) difference between the voltage
levels.

The +4dBu standard is the true professional one. -10dBV was introduced by Tascam
IIRC as a lower cost alternative for 'prosumer' kit. It's not really relevant
any more since modern electronics has the required headroom anyway.

Graham

 

[Eeyore]

Line level is a higher level than speaker level

You mean mic or instrument level I think.

- it means a signal you can
pass to another device. I'd assume it's about 100 mV to 1V but it varies
anyway.

Yup.

Graham

 

[Eeyore]

I think you must have mistyped there Homer. Speaker level is more like 10v
and up. Line level is much lower than that. I agree with the 100mV at the
low end, but I've seen CD players with a line out of 2 or 3v. Same ballpark
though. For the OP and anyone else who's interested, this site is awesome:

http://www.sengpielaudio.com/Calculations03.htm

CD outputs are indeed meant to be 2V for max signal level.

Graham

 

[Homer J Simpson]

10 volts into 8 ohm headphones? Not on MY ears!

 

[Don Bruder]

10 volts into 8 ohm headphones? Not on MY ears!

Regardless, "speaker level" is indeed higher (usually MUCH higher) than
"line level". Even "headphone level" is almost always significantly
higher than "line level".

Line level is typically hanging in one of two ranges: About 0.25-0.5V
P-P for "consumer grade" gear (without bothering to look it up, I'm
wanting to say that "offical" line level for consumer gear is 0.3V P-P)
and roughly 1V P-P for broadcast/"pro" level gear.

Speaker level, on the other hand, might go into tens or even hundreds of
volts, depending on exactly what kind of gain is needed.

 

[BobG]

I think the idea is that is the average level is 0dBV on the meter, you
still have 20dB headroom for peaks. If the +20dBV level is 14V (max
opamp output), 20 dB below that would be about 1.4V peak. Now we can
get into another argument about where the average for music is... is
it .707 like rms for a sine wave, or .637 like avg level for a sine
wave, or just .5 or 6dB like 'music power'?

 

[Eeyore]

I think the idea is that is the average level is 0dBV on the meter, you
still have 20dB headroom for peaks. If the +20dBV level is 14V (max
opamp output), 20 dB below that would be about 1.4V peak. Now we can
get into another argument about where the average for music is... is
it .707 like rms for a sine wave, or .637 like avg level for a sine
wave, or just .5 or 6dB like 'music power'?

dBV isn't used much these days for audio.

What do you mean by an average anyway ? The dynamics of different styles of
music push the level allo ver the place from one moment to the next. The
concept of average isn't teriibly helpful. You need to avoid distorting the
loud passages.

Graham

 

[BobG]

What do you mean by an average anyway ? The dynamics of different styles of
music push the level allo ver the place from one moment to the next. The
concept of average isn't teriibly helpful. You need to avoid distorting the
loud passages.

=======================================================
I was interested in using the rms to model as the dc heating in the
voice coil as a speaker protector... I wrote some programs that graphed
a music wave, its avg, and its rms, and was surprised to see the rms
riding about 3dB above the avg. I expected the 'crest factor' to be
more variable with wave shape. The conclusion was: use a long time
constant avg (seconds), set the threshold 3dB below the power handling
capability of the speakers, dont let the clipping indicators stay on
too much.

 

[Eeyore]

=======================================================
I was interested in using the rms to model as the dc heating in the
voice coil as a speaker protector... I wrote some programs that graphed
a music wave, its avg, and its rms, and was surprised to see the rms
riding about 3dB above the avg. I expected the 'crest factor' to be
more variable with wave shape. The conclusion was: use a long time
constant avg (seconds), set the threshold 3dB below the power handling
capability of the speakers, dont let the clipping indicators stay on
too much.

3dB doesn't surprise me for modern music at all.

Try it with some classical !

Graham

 

[BobG]

3dB doesn't surprise me for modern music at all.
Try it with some classical !

===================================
If you are not surprised, then you must have given some thought to how
much difference exists between the rms and average for various
waveshapes or musical styles. I have no idea if the avg would be MORE
db above the rms or LESS for classical. Do you have a prediction? Maybe
I can make a cmd line version of my wave analyzer, and we can both run
it?

 

[tempus fugit]

I'm sure it would be more for classical. Modern music is so compressed that
you have very little in the way of dynamics, so there is probably not a
whole lot of difference between the average and the actual peaks. Classical
is much more dynamic, and so would have some VERY loud peaks at the peaks.