tacman7
The way I was told...
 
If you turn up the ratio of a compressor to 10 or above, you're limiting.

At the risk of re-starting the "discussion", you were told wrong.
 
A compressor with a ratio of 1000:1 is still a compressor... it may give a similar result to limiting and my be considered a limiter by some people but its NOT limiting...  The output will still rise by 1db for every 1000db rise in input (sounds ridiculous, I know, but transients from drum hits and other percussive sounds will produce those sort of gradients).
 
A limiter will prevent the output from rising regardless of the input...

Also most true limiters have a look ahead buffer to prevent intersample clipping. I don't know of a compressor that has a look ahead buffer. There may be some but I haven't come across any.

Karyn

tacman7
The way I was told...
 
If you turn up the ratio of a compressor to 10 or above, you're limiting.

...A limiter will prevent the output from rising regardless of the input...

In that case is should be called a "clipper". If that is what is desired than just run the signal up to 0dBFS..
 
Walt
 

Well it is called a limiter already not a clipper.

Joey, all the answers above explain what a limiter is, but so far nobody's addressed your real question, which is how to balance loudness from one song to the next. A limiter does come into play, but the primary tool you'll need is actually a good meter. That will let you set how hard the limiter is driven and thereby adjust the perceived volume.
 
A good place to start with metering is Voxengo SPAN. It's easy to use, it's free, it supports a widely-used standard for gauging levels called the K-system, and it's an excellent tool for adjusting loudness to whatever standard you choose. 
 
You can get more scientific with an EBU loudness meter, but I'd hold off on that for now. Get a copy of SPAN and insert it on the master bus, at the end of the chain after everything else. Put it into Mastering Mode, set the meter to K-14 and adjust the input to the limiter until your levels are hovering around the 0 dB mark (which is actually 14 decibels below the real 0 dB, and that's the point of the K system).
 
With your levels bouncing around the 0 dB mark, if your song is still too dynamic and/or not loud enough, add a bus compressor in front of the limiter. But if you can get the desired results without master bus compression, that's better.

CJaysMusic
 
Study, study and study all the things that a limiter and a compressor has. Like learn what the Ratio is, the Threshold is, the Attack is, the Release is, the knee and Auto gain and Gain are.
 
All you need to do is learn what all these things do and you will learn how to use any limiter and any compressor.
 
CJ

All I can add to this is search out resources such as books, online articles, and such for info to study. This is not something you will grasp correctly first go around.

bitflipper
... but so far nobody's addressed your real question, which is how to balance loudness from one song to the next.

Ummm ... I thought I had a crack :). Yes - your answer is more complete and getting to the lower level.
 
@bitflipper - I see you've posted on the HoRNet AutoGain (Pro) before ... What are your thoughts of it (and/or similar) as a means of accomplishing what @Joey's after?
 
(I have no affiliation to HoRNet - just purchased it in their sale yesterday (now over)).

bitflipper
Joey, all the answers above explain what a limiter is, but so far nobody's addressed your real question, which is how to balance loudness from one song to the next. A limiter does come into play, but the primary tool you'll need is actually a good meter. That will let you set how hard the limiter is driven and thereby adjust the perceived volume.
 
A good place to start with metering is Voxengo SPAN. It's easy to use, it's free, it supports a widely-used standard for gauging levels called the K-system, and it's an excellent tool for adjusting loudness to whatever standard you choose. 
 
You can get more scientific with an EBU loudness meter, but I'd hold off on that for now. Get a copy of SPAN and insert it on the master bus, at the end of the chain after everything else. Put it into Mastering Mode, set the meter to K-14 and adjust the input to the limiter until your levels are hovering around the 0 dB mark (which is actually 14 decibels below the real 0 dB, and that's the point of the K system).
 
With your levels bouncing around the 0 dB mark, if your song is still too dynamic and/or not loud enough, add a bus compressor in front of the limiter. But if you can get the desired results without master bus compression, that's better.

Well perhaps you missed my answer post # 2? 

but so far nobody's addressed your real question, which is how to balance loudness from one song to the next

 
Its done with your ears.

Sort of on topic and sort of not:
 
There is a new software product called Perception that seems interesting.  The concept is that it allows you to play a mix with and without your master bus effects and with comparable **perceived** volume.  In other words, when you turn the effects off, Perception uses a sophisticated algorithm to keep the perceived volume consistent so you can hear what your effects (e.g., compression, master bus EQ) are doing to your mix without the confusion of volume changes.  This can also be used on individual tracks.
 
That is an oversimplified explanation but hopefully gets the basic concept across.  I imagine mastering engineers and artists who master their own work would find this very useful.