What is line level audio?

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

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.

can

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:

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

You mean mic or instrument level I think.

Yup.

Graham

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

Graham

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.

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

======================================================= 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.

Try it with some classical !

Graham

=================================== 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?

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.