the human ear hears loudness in a way peak meters cannot represent. It's actually possible to have a really loud mix without your meters even being CLOSE to 0dbFS. There's a separate metering called RMS metering that represents "loud" better. This is why I advocate always mixing with an RMS meter.
Without delving way too deep into the topic of the loudness wars and how to get a really loud mix and not ruin the dynamics of your song (because it happens all the time)...it's actually the peaks you're watching on your peak meter that are robbing you of loudness. Most likely in the drums. Because you're only able to turn up a snare track so much before it starts to clip, you're restricted to only a certain volume. This in turn forces you to do the same for all the other tracks, so the end result is an apparent "quiet mix."
But what if you could limit those peaks on the snare drum? Say they are peaking right now around -3dBFS...what if you could limit them to around -7dBFS? Then you add a make up gain to turn them up even louder, knowing that they'll never go beyond a certain point...which you'll know that certain point. What happens is when you have peaks at -3dBFS, your RMS for that track is probably way lower...maybe somewhere at like -15dBFS (I'm just throwing out a number, each track varies). But if you've limited the peak to not go above -7dBFS, your RMS level is STILL -15dBFS. And remember, RMS is a better representation of how we perceive loudness. So it's going to be the same loudness, you've just controlled the peaks of the instrument. Then you can turn up the track even louder..maybe another +4dBFS. So now you're peaks are at -3dBFS (the same place they were earlier before peaking)...but your RMS level is at -11dBFS! You're just turned up that snare track +4dBFS (roughly doubled the loudness) without clipping the track.
Try another experimentation. Play back your track as is (without limiting yet) and watch your levels. Listen to how loud it is. Now take the drums or any other transient material out and listen to how loud it is...and watch the meters. The peak meters will drop dramatically. And you actually can turn your mix up more. It's usually the drums that are robbing you of this. So good tracking and mixing skills can give you some more headroom.
The problem is this can ruin your dynamic range. Most people don't mind sacrificing this for volume...others argue that a dynamic range is the most important aspect of a song. I think it's a balance between both. A lot of people want volume so we have to give it to them. But you don't want to ruin the quality of your mix, so you have to limit/compress tastefully. The more you practice mixing the more you'll hear the difference between tasteful and not.
Of course usually I just respond to these posts with "your mix isn't as loud as the Red Hot Chili Peppers??? just turn up your speakers then." Which gets some gripes from people. But there are much more important things to pay attention to in your mix than comparing your volume to other CDs. Especially CDs that are recorded, mixed and mastered by professional musicians, with professional engineers, on professional equipment in the most professional facilities. It's like a college kid saying "my pot roast doesn't taste at all like the fancy restaurant's does down the street." Especially if this is first time cooking!
Don't worry so much about how your mix sounds volume wise right up next to someone elses. This isn't a pissing contest...it's music.
HTH
