What are my RMS meters telling me?

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RAMI

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I always took for granted that my "Average level" meters were telling me just that, the average volume of a song. But now, I'm not so sure I've understood it 100%.

Here's my question/problem. When I'm "mastering" a song (I use REAPER by the way), I'll play the song all the way through, and at the end I see that the average level meter is telling me the average level was -12.4 (for example). But what I noticed is that, during the course of a song, the "average" level never goes down on the meters, only up. In other words, I can have a really loud intro that averages -12.4 (for example). But even if the rest of the song in very soft and no way near the volume of the intro, the average will stay at -12.4 until the end of the song, no matter what. Shouldn't it go down during the course of the song if the other 3 minutes are half the volume of a 10 second intro?

Maybe I mis-understood what is meant by "average level" all along? Could it really mean the "average level" during the loudest part, sort of thing?
 
47 views and no replies???

Oh wait, 42 of those are mine. The other 5 were "guests".

Never mind.

:D
 
Aren't your meters telling you the max RMS level ?
In other words, it's continuously measuring/integrating RMS on a short period of time and then provides you with the highest value.
SOrt of "your loudest part of the song is at -12 dB, you should be proud" (REAPER is very nice you know)
:)
 
roffli said:
Aren't your meters telling you the max RMS level ?
In other words, it's continuously measuring/integrating RMS on a short period of time and then provides you with the highest value.
SOrt of "your loudest part of the song is at -12 dB, you should be proud" (REAPER is very nice you know)
:)
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Yes REAPER is great.

Thanx for making it clearer. You confirmed what I thought might be the case. So it's giving me the highest RMS level in the song. I mis-understood it as the "average" (that word threw me off) volume, not the highest value.

Thanx . :cool:
 
I know I'm going to get this wrong and I probably shouldn't even try to respond, but...

If I remember correctly, RMS is the square root of the squares of the average of a varying signal. Basically, it's a way to find a happy medium of a varying signal and measure it. You have the wave form of your song going up and down. Sometimes the peaks are higher, and sometimes they are not as high (insert refernce to people if you are so inclined :D ), but the peaks don't really represent what the total waveform is doing.

So, mathemeticians came up with a way to measure different waves and be able to compare them; RMS. As a rule of thumb, the RMS value usually comes out close to .707 of the peak value of a wave. I'm willing to bet that's what most digital plug in type meters are doing. It's not quite accurate. (I think an analog RMS meter is probably more accurate, but can't really explain why. I want to think it has something to do with the weight of a needle, inertia and how it has an averaging affect. But off topic..)

So here's where I think RMS meters fall apart in music. From my own experience...

I mastered my last CD and it came out okay, not great... I tried using an RMS meter to set all the songs to the same level and it didn't work. What I found was that although the RMS values matched, the songs with less stuff going on seemed much louder. Like, an acoustic and vocal only song was much louder than a song with tons of distorted guitars and everything. I would have thought it would be the other way around, but SouthSide Glen (remember him?) said it the best; sonic density. A song with more stuff going on has a more information crammed into the waves, lots o' harmonics and everything. The acoustic stuff doesn't have a lot so the waves are more sparse, cleaner, or closer to sinusoidal. This impacts the RMS values and when trying to match them up, will significantly raise the perceived volume of the softer stuff over the harder stuff.

Yeah, I didn't explain myself good enough... I don't completely understand it, either. But SSG's comment on sonic density really explained a lot of what I was seeing. It's the reason why we still need to use our ears and not just meters. (Not saying that you don't... :o )

Maybe there's enough misinformation here that someone who knows can chime in and set me straight.... lol
 
Oh... all that work and it probably wasn't even what you were asking... ha ha ha.. that's okay. :D
 
Chili said:
Oh... all that work and it probably wasn't even what you were asking... ha ha ha.. that's okay. :D
Click to expand...

No, that helped me immensely because I noticed the same thing about sonic density. I have two or three songs that are just 4-piece (drums, bass, one guitar track, vocals), and they always come out sounding louder than the fuller songs I have with doubled guitars, etc....even though the RMS level is the same.

It doesn't bother me any more because I don't rely on the RMS meter as much, like you said. But it used to drive me nuts. I'd actually go back and re-mix songs so that they'd be same level as the other songs at the same RMS. I'd do stupid things like "well, if I turn up the bass, it will make the song denser and hopefully pull down the level". So, I was making the mistake of mixing for the limiter instead of just mixing the song to sound as good as it can.
 
RMS is a sort of average over time. That time can be the whole song or some given amount of time. An RMS meter is probably using some time constant to give you an idea of the RMS in the part of the song you're playing. The RMS you're describing sounds like the "maximum RMS" of the song.

Although I do use my ears to finalize the volumes of songs on an album, I first get them all in the ballpark by using RMS numbers. If a song is particularly dynamic then I just measure the loudest part of the song. That's similar to the max RMS you're describing.
 
What your RMS meters are telling you will also be dependent on what speed you set the ballistics too. REAPER Defaults to 300ms as I recall which also happens to be more or less how a real VU meter reacts. This takes the very fast transients out of the equation so that the meter is giving you a more overall picture of how powerful the signal is at a given instant that you are looking at it
You cant just play the song and let the meters go and then look at what the peak RMS value was to say that is how loud the song is however. it's just a measure of what the loudest peak RMS was
If you're routing out to analog gear you still need to watch the meters to ensure the output signal is dancing around line level or however hard you want to drive the gear into its headroom
If you're pure in the box I guess it matters if you are pushing the signal into analog emulation VST plugs that will give emulated signal distortion at higher levels
If you're ITB using no emulation plugs then so long as you stay below zero I guess the RMS values are less important although it's still fun to watch VU meters dance :)
 
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