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How do you make sure you are hitting Nebula at -18dbfs?

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Re: How do you make sure you are hitting Nebula at -18dbfs?

Postby david1103 » Wed Jan 07, 2015 7:31 pm

Its AVERAGE RMS you want.

Massive section on this in Nebula Explained http://www.learndigitalaudio.com/nebula

Lots free plugin meters to load up on the insert channel before Nebula for this.

Since that came out there has been an amazing free addition to Reaper in the SWS/S&M extension:

http://wiki.cockos.com/wiki/index.php/M ... s_with_SWS

You can normalize your tracks to -18dbfs RMS at the press of a button, or any amount you want.

You might well find -18dbfs is too loud for drums and will cause clipping, so watch out for that :o
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Re: How do you make sure you are hitting Nebula at -18dbfs?

Postby budda963 » Wed Jan 07, 2015 9:51 pm

Here's my concern David, and hopefully you'l be able to straighten me out. (I'm not arguing to prove you wrong, I just want to get a full understanding)

VU meters generally measure RMS with about 300ms of range correct?
Pro tools Normalize calculates the RMS based on the length of the entire clip. So even if the clip is 4 minutes long, then the lowest volume and highest peak are averaged.

Thus, when you use normalize (at least in pro tools), the end result is way louder than 0 on a VU meter. In fact, its usually pinning the meter.

If you're saying this is the way to hit nebula then great, thats exactly what I'll be doing. But if thats not the way to do it, then I either need to stick to doing it by hand or maybe aim for -6dbfs peak instead of an RMS value when using a normalizer.

I've attached a screenshot of my VU when I've normalized a sine wave to -18db rms in pro tools. You can see that its stuck at +3. Wouldn't I want it closer to zero?
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Re: How do you make sure you are hitting Nebula at -18dbfs?

Postby david1103 » Thu Jan 08, 2015 12:20 am

VU meters generally measure RMS with about 300ms of range correct?


Yes, that's standard

Pro tools Normalize calculates the RMS based on the length of the entire clip. So even if the clip is 4 minutes long, then the lowest volume and highest peak are averaged.


Yes, but you must check settings to see if it uses a 300ms window in its overall calculation. It may not be acting like a VU meter.

Thus, when you use normalize (at least in pro tools), the end result is way louder than 0 on a VU meter. In fact, its usually pinning the meter.


OK, you mean 0 on the VU now it is calibrated to -18dbfs? You say 'pinning the meter', depends on your meter settings. You only have 3dB extra displayed on your meter screenshot.

If you calibrate some audio to be average -18dbfs RMS then that is what it should be. It could still clip if it had strong transients (like drums) that had a massive crest. You need to watch the peak too. This is my favorite meter for pc:

http://www.youtube.com/watch?v=BfzQNmc32cc

but i think the site has gone now.

I would try again with normal audio rather than a sine wave and check your pro tools normalize settings.

The audio into Nebula on average should be -18dbfs RMS, if you want less variation it will need compressing in advance or chop the audio into different sections and normalize them separately.
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Re: How do you make sure you are hitting Nebula at -18dbfs?

Postby babiuk » Fri Jan 09, 2015 2:16 am

Well, I think the best solution to hit nebula instances with a -18 signal may be "Auto Gain Staging JSFX" by TBProAudio.

http://forum.cockos.com/showthread.php?t=141370

Am I right? Or maybe this normalization ways could be better or safer? I am so interested in knowing if this plugin is a 100% effective tool for this target.

I think it works by processing your audio and sending it into nebula at (well, you choose it) -18dbfs level. Once into Nebula you can use input knob in an "analogic" way like an input knob from real gear.

Correct me if I am wrong, please, but I think this plugin does not affect over output from nebula
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Re: How do you make sure you are hitting Nebula at -18dbfs?

Postby giancarlo » Fri Jan 09, 2015 8:14 am

-18dBFS is a peak value,not RMS
Pay attention if you want to address to nebula usage: most of compressors and preamps are based on peak (L infinite norm) and not RMS (L2 norm)

Gdrive itself is based on peak.
You need to normalize your audio to -18. Rms will work in most of cases, but there is at least a 6dB difference in most of cases
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Re: How do you make sure you are hitting Nebula at -18dbfs?

Postby ngarjuna » Fri Jan 09, 2015 11:39 am

giancarlo wrote:-18dBFS is a peak value,not RMS
Pay attention if you want to address to nebula usage: most of compressors and preamps are based on peak (L infinite norm) and not RMS (L2 norm)

Gdrive itself is based on peak.
You need to normalize your audio to -18. Rms will work in most of cases, but there is at least a 6dB difference in most of cases

Why would you use peak values to gain stage? And why normalize when it's as simple as reading a meter and adjusting the input on that basis? The meter is a guide to get you into the neighborhood, the adjustment (of how hot you're going into a Nebula instance) should be based on how it sounds. Do you want to drive the input a little? Do you want to go in cool and clean? There's no magic normalization number that's going to make that adjustment for you.

Gain staging is an important subject if you want to use analog equipment same as Nebula. Take the time to learn and understand it and you'll never have another question about how to hit Nebula.
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Re: How do you make sure you are hitting Nebula at -18dbfs?

Postby budda963 » Fri Jan 09, 2015 3:40 pm

ngarjuna wrote:
giancarlo wrote:-18dBFS is a peak value,not RMS
Pay attention if you want to address to nebula usage: most of compressors and preamps are based on peak (L infinite norm) and not RMS (L2 norm)

Gdrive itself is based on peak.
You need to normalize your audio to -18. Rms will work in most of cases, but there is at least a 6dB difference in most of cases

Why would you use peak values to gain stage? And why normalize when it's as simple as reading a meter and adjusting the input on that basis? The meter is a guide to get you into the neighborhood, the adjustment (of how hot you're going into a Nebula instance) should be based on how it sounds. Do you want to drive the input a little? Do you want to go in cool and clean? There's no magic normalization number that's going to make that adjustment for you.

Gain staging is an important subject if you want to use analog equipment same as Nebula. Take the time to learn and understand it and you'll never have another question about how to hit Nebula.


Giancarlo: I don't understand how the -18dbfs could be a peak figure when the equipment of those days didn't measure peaks. Many signals normalized to -18dbfs peak wouldn't even move the meter on a VU.

ngarjuna: I've been gain staging manually on a track by track basis but I was interested in seeing if I could speed up the workflow a little bit.

My general idea has been to get the VU meter hitting 0 or maybe +1 during the loudest parts of my signal. But that is definitely not -18rms or -18dbfs. If I'm not mistaken that figure is referred to as "-18db rms at max". It's almost like taking a peak reading from the VU meter. Of course the peaks are louder than -18dbfs but the meat of the signal is at -18. (Do i sound like a lunatic? lol. Maybe I have this whole idea wrong)
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Re: How do you make sure you are hitting Nebula at -18dbfs?

Postby ngarjuna » Fri Jan 09, 2015 4:00 pm

budda963 wrote:
ngarjuna wrote:
giancarlo wrote:-18dBFS is a peak value,not RMS
Pay attention if you want to address to nebula usage: most of compressors and preamps are based on peak (L infinite norm) and not RMS (L2 norm)

Gdrive itself is based on peak.
You need to normalize your audio to -18. Rms will work in most of cases, but there is at least a 6dB difference in most of cases

Why would you use peak values to gain stage? And why normalize when it's as simple as reading a meter and adjusting the input on that basis? The meter is a guide to get you into the neighborhood, the adjustment (of how hot you're going into a Nebula instance) should be based on how it sounds. Do you want to drive the input a little? Do you want to go in cool and clean? There's no magic normalization number that's going to make that adjustment for you.

Gain staging is an important subject if you want to use analog equipment same as Nebula. Take the time to learn and understand it and you'll never have another question about how to hit Nebula.

ngarjuna: I've been gain staging manually on a track by track basis but I was interested in seeing if I could speed up the workflow a little bit.

Gotcha, you want this sort of 'pre-process' to get you into the ballpark then? That does make sense, yes, particularly if you're dealing with source material that by and large doesn't conform to the levels you want to input.

In terms of VU metering, generally speaking we don't use 0 VU to mark the top of the range but it depends what you want to accomplish. Back in the day 0 VU ('nominal level') often used to demonstrate the top of the clean range. Then the headroom above that represents the amount you can drive the signal over nominal. So if you want the hottest parts of your signal to still hit the processor very cleanly without saturating you would indeed aim your hottest levels for around 0 VU. But…if you want to drive the input then you want more average levels (before things get hotter) to hit 0 VU so that when it gets hotter you're pushing into that driven range.

Reading VU meters isn't a very scientific process which is why it's hard to script preset rules about them, particularly when you consider the massive difference in response between transient rich and steady state signals. But since you're working so far below 0dBFS peak I think you'll probably be able to stay out of trouble regardless.
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Re: How do you make sure you are hitting Nebula at -18dbfs?

Postby babiuk » Fri Jan 09, 2015 9:13 pm

I always thought hitting nebula with a given level was something regarding RMS not peak, but Giancarlo's post nakes me doubt...

I think normalizing -18 peaks of a drum track will get into nebula good and right peaks but a low rms signal which is a poor level for proccessing.

Maybe brickwall limiting peaks and using autogain plugin could be better?

What do you think of autoplugin?

I am confused now and I'd like to know how to operate the best way to get the best of nebula
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Re: How do you make sure you are hitting Nebula at -18dbfs?

Postby Support » Sat Jan 10, 2015 12:21 pm

Best regards,
Enrique Silveti.
Acustica Audio customer and technical support
http://www.acustica-audio.com
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