PDA

View Full Version : levels of the mix bus during mix-down....does it need to be near 0 dbfs?


Felix
01-14-2002, 10:00 AM
since that huge level setting thread, my mixing has changed dramatically in more ways overall than level settings. instead of having to lower all the track levels when the mix bus has to be lowered, my mixes are hitting the mix bus at -10dbfs of less. sometimes as low as -20 dbfs. by raising overall levels, i can get up to -6 or -5, but it doesn't seem to make it sound better. it sounds quite nice at the lower levels. i've tried setting my monitors at lower levels, but i still seem to have the same results.
is this a problem? i remember reading somewhere that mastering labs like to see mixes that do not slam the peaks- mixes that are as low as -20dbfs are more master-friendly.
so, do i need to find ways to crank up my levels(ie. cut louder tracks, do more boosting than cutting), or should i just let it be?

PTUser NYC
01-14-2002, 11:13 AM
I'm one of those who believes in observing 0dbVU throughout the recording process. I think Pro Tools (at 24bits!) sounds so much better when I track with peaks around -14dbFS (which is referenced to 0dbVU on my Apogee). I can't say whether this is a headroom issue within the mix bus(es) of Pro Tools, or simply better sound from my analog front end. Either way, I'm sold, and the difference in sound is not subtle.

The problem is that when I have a good finished mix, the peaks are often 10db or so shy of Full Scale. Naturally, I want my CDs to compete in level with other releases. Often, I am doing advertising work, which will not include mastering, and which will compete against other work in a CD player at the agency. In these cases, I want my CDs to be as loud as possible.

Now, I'm not talking about further compression or 'mastering', I'm just talking about raising the level of the mix so that peaks are 2/10th of a db shy of Full Scale. This is also a good idea if you are going to 'dither down' to 16 bits, which is inevitable for pressing a CD. 24 bits sounds fine peaking at -14dbVU, 16 is another story.

I have found that when using the Rennaisance compressor across the mix bus, that after I have made all my aesthetic choices, using the gain on the plug in is a good way to raise the overall level.

You can choose to use the master fader IF you don't have any plug ins on it AND IF you only need 6db more. In my experience, neither one of these things is usually true.

So, go ahead and observe 0dbVU, make your choices as you will without regard to beefing up the mix bus level, and then add gain at the end. It works great for me.

There are other plug ins that are good for raising gain too. I'm careful not to chain too many plug ins on the master fader, so since I often use the Rennaisance compressor as a 2 bus compressor, I like to do the gain change there too. You may prefer to use a different plug in.

The point here is simply that you can observe 0dbVU throughout the recording and mixing process, and not have to worry about the mix level until after you have made all your choices.

Kyle

Mike Tholen
01-14-2002, 11:07 PM
images/icons/wink.gif Yes! Kyle, your right on.
Observe 0dBVU throughout the recording/mixing process.
If you need to burn a disc for reference use a plug (one).
I send stuff to mastering joints at 0dBVU.
which just happens to be exactly where I'm at with my gain structure at "the 2 buss". images/icons/tongue.gif

CO2
01-15-2002, 12:21 AM
Hello Felix:

I agree with Kyle & Mike.

Maintaining 0 dbVU (-20 dbFS RMS) average throughout seems to be the right answer. It helps to simplify the digital gain stage math processing. Sort of digital's version of a wire with gain.

I use the L1 or Master X plug on the Master fader only when cutting a reference mix CD to compensate level to compare more favorably to mastered discs.

I call that final stage processor my "Sheryl Crow Tweak" (S.C.T.). The amount of compression, coupled with the full scale mastering level, on one of her discs represents the epitome of LOUD!!! (IMHO)

I did a little test (VERY UNscientific, so PLEASE don't bag on me) using the tune "A Change Will Do You Good" as a mastered reference.

I loaded it from the AES digital output of my Sony CD player through my Z Systems digital router into the 888/24's AES inputs to a 44.1 KHz 16 bit original music session I had mixed in Pro Tools.

The original music was mixed adhering to the 0 dbVU average throughout concept. It was a nice full sounding mix that I was pleased with UNTIL I opened the Sheryl Crow mix!

images/icons/shocked.gif

Needless to say, THAT is what we find ourselves forced to compete with when we create reference mix CD's. We all know THAT is what most producers are going to compare our ref CD mixes to. Hence the need for the S.C.T.

Of course, the good news is we can eliminate the S.C.T. when we prep our music tracks to go to the mastering engineer. The bad news is we are stuck with some form of S.C.T. in Post!

Best Regards

Felix
01-15-2002, 09:40 AM
thanks, y'all!
i figured i was on the right track.

joy4u
01-15-2002, 09:55 AM
In the real world, the problem is not reaching 0dB, the problem is AVOIDING SURPASSING IT!!!! images/icons/wink.gif
When i mix, i always finish clipping the master, no way how low i start.
To avoid it i often start with all tracks at -15dB or less, then it's good.

But yes, try to be always as hot as possible in the master, but the audio mixing rules are always the same: dont lower any level if you will have to rise it in a successive stage of the mix.

Park Seward
01-15-2002, 11:26 AM
Bob Katz has some good thoughts on levels and mastering...
http://www.digido.com/

"In the music and broadcast industries, chaos currently prevails. Here is a waveform taken from a digital audio workstation, showing three different styles of music recording.. The time scale is about 10 minutes total, and the vertical scale is linear, +/- 1 at full digital level, 0.5 amplitude is 6 dB below full scale. The "density" of the waveform gives a rough approximation of the music's dynamic range and Crest Factor. On the left side is a piece of heavily compressed pseudo "elevator music" I constructed for a demonstration at the 107th AES Convention. In the middle is a four-minute popular compact disc single produced in 1999, with sales in the millions. On the right is a four-minute popular rock and roll recording made in 1990 that's quite dynamic-sounding for rock and roll of that period. The perceived loudness difference between the 1990 and 1999 CDs is greater than 6 dB, though both peak to full scale. Auditioning the 1999 CD, one mastering engineer remarked "this CD is a lightbulb! The music starts, all the meter lights come on, and it stays there the whole time." To say nothing about the distortion. Are we really in the business of making square waves?


The average level of popular music compact discs continues to rise. Popular CDs with this problem are becoming increasingly prevalent, coexisting with discs that have beautiful dynamic range and impact, but whose loudness (and distortion level) is far lower. There are many technical, sociological and economic reasons for this chaos that are beyond the scope of this paper. Let's concentrate on what we can do as an engineering body to help reduce this chaos, which is a disservice to the consumer. It's also an obstacle to creating quality program material in the 21st century. What good is a 24-bit/96 kHz digital audio system if the programs we create only have 1 bit dynamic range?

New program producers with little experience in audio production are coming into the audio field from the computer, software and computer games arena. We are entering an era where the learning curve is high, engineer's experience is low, and the monitors they use to make program judgments are less than ideal. It is our responsibility to educate engineers on how to make loudness judgments. A plethora of peak-only meters on every computer, DAT machine and digital console do not provide information on program loudness. Engineers must learn that the sole purpose of the peak meter is to protect the medium and that something more like averagelevel affects the program's loudness. Bear in mind that the bandwidth and frequency distribution of the signal also affect program loudness.


As a music mastering engineer, I have been studying the perceived loudness of music compact discs for over 11 years. Around 1993 I installed a 1 dB per step monitor control for repeatability. In an effort to achieve greater consistency from disc to disc, I made it a point to try to set the monitor gain first, and then master the disc to work well at that monitor gain.
In 1996, we measured that monitor gain, and found it to be 6 dB less than the film-standard for most of the pop music we were mastering. To calibrate a monitor to the film standard, play a standardized pink noise calibration signal whose amplitude is -20 dB FS RMS, on one channel (loudspeaker) at a time. Adjust the monitor gain to yield 83 dB SPL using a meter with C-weighted, slow response. Call this gain 0 dB, the reference, and you will find the pop-music "standard" monitor gain at 6 dB below this reference."

Use -20 dbFS as your reference. you don't need to get close to 0.

Extreme Mixing
01-15-2002, 11:32 AM
I don't know...I'm one of the guys who advocates recording into Pro Tools at fairly conservative levels. I think it sounds better because my analog front end sounds best at those levels (around 0 to +3 on a VU meter), but I think you should keep the mix buss as full as possible. I don't have much trouble getting those levels up to the top of the meters.

I think the guys who understand the math will all agree that, once you get into the digital mixer, you should work as close to full scale as possible to get maximum resolution out of the digital environment and the storage media, be it 24 bit dat or 24 bit SD II files. If the guys at mastering want to calibrate their DA converters to avoid hitting their analog gear too hard, they can easily do that. They should be able to handle your mastering session with no problem.

What they don't want to recieve at mastering is a 24 bit file that you have already compressed and limited to death. They want to do that. We could talk all day about what happens to the sound of your mix when it's smashed like a bug on the windshield of Peterbuilt 18 wheeler by a mastering engineer who aims to make his records the loudest ones on the planet. But these guys are paid well to run your mix throught their half million $ worth of gear. Hopefully, it sounds better than your L1.

When I send clients home with reference CD's, I usually turn it up a bit with an L1. That's just to keep the level competitive with what's out there. Like was said above, how much impact your song has is pretty closely related to how loud it is in compared to the song just before and after. You don't want to be the small thin sounding one, do you?

I don't see any benefit to letting mixes out in the -10 to -20 dbfs range. If you think the music and your mix sounds best at that level, my advice is always go with what sounds best to YOU.

Good mixing,

Steve

CO2
01-15-2002, 03:33 PM
Hello Park:

Thank you for invoking the wisdom of Mr. Katz!

We all benefit from Bob's many years of experience and his ability to translate that experience into user friendly text.

Putting his wisdom to practical use could greatly enhance the quality of the digital experience.

Thanks again!

Best Regards

Steve MacMillan
01-15-2002, 08:55 PM
If you find yourself comparing all the different loud box plugins (L2, L1, MasterX, etc.) in order to maximize your mix, don't rule out a couple of db into clipping on the master buss without any plugins. With many kinds of pop and R&B mixes a little clipping is not broken. And except for the clip, it does nothing against the rest of the mix.

sm

CO2
01-15-2002, 11:00 PM
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:<HR>Originally posted by Steve MacMillan:
[QB...don't rule out a couple of db into clipping on the master buss without any plugins. With many kinds of pop and R&B mixes a little clipping is not broken.

sm[/QB]<HR></BLOCKQUOTE>

Hello Steve:

I don't believe I have ever seen anyone promote digital clipping before! I'll presume you are offering this advice tongue in cheek.

True many old R&B and Rock records were driven to clip, but on analog tape (Tape saturation produced one form of the warmth all us old analog types miss so much in digital).

Correct me if I am wrong, but nothing good comes from clipping digital!

Best Regards

Corey Shay
01-16-2002, 12:00 AM
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:<HR>Originally posted by CO2:


Correct me if I am wrong, but nothing good comes from clipping digital!
<HR></BLOCKQUOTE>


Well, if I may in a tounge-in-cheek manner correct you sir. Sometimes... Well, rarely, yes, but sometimes it actually works for the song. And I don't mean on single tracks, I mean the whole darn mix into clipping can enhance it a bit. It can make things sound heavier at times in a way. And this it can do in ways that peak-limiting with L1/L2 really can't.

That being said, on the rare occasions when I've done this, I don't think I've ever gone a couple dB "over". Maybe 3 dB tops.

Back to the original topic, I have no problem getting my levels on my mixbuss as high as possible without lighting up a clip. In my opinion you are wasting perfectly usable dynamic range and resolution if you do not. This is all to assume you are 100% digital in the mixdown. Once again, this all being said, at times what you are looking for is a low-resolution sound... But in practice I've only done this on single tracks (recording very low) and not the whole mix.

It's art. And true art has no rules. The guidelines however will get you where you need to be 95% of the time.

Steve MacMillan
01-16-2002, 01:47 AM
CO2 say...

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:<HR> I don't believe I have ever seen anyone promote digital clipping before! <HR></BLOCKQUOTE>

Well I guess now you have. images/icons/wink.gif Let your ears be your guild. If it sounds bad don't do it. But if loud is what you want, sometimes the limiters rob punch and the clip doesn't. In this world of a million hard rock bands, rap & hip hop, and louder than the next R & B tracks, I'm not going to be squeamish about a clip that doesn't sound bad (and maybe sounds good).

sm

audiaudio
01-16-2002, 03:33 AM
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:<HR>Originally posted by Steve MacMillan:

. . . if loud is what you want, sometimes the limiters rob punch and the clip doesn't. . . . I'm not going to be squeamish about a clip that doesn't sound bad (and maybe sounds good).
<HR></BLOCKQUOTE>

I agree with Steve MacMillan.

Take a look at the waveform of virtually any contemporary hit R&B cut (i.e. Rodney Jerkins, Neptunes, etc), and you'll see not just a few but many flattened overs.

Yep, flat-out digital clips. And lots of 'em.

Many people, myself included, like the sound of those CDs. An argument can be made (and Steve MacMillan is making it) that the frequent, momentary clip and increased overall level can be more useful than compression/limiting alone in getting a torqued, punchy, contemporary sound.

Dr. J
01-16-2002, 07:37 AM
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:<HR>Originally posted by audiaudio:


I agree with Steve MacMillan.

Take a look at the waveform of virtually any contemporary hit R&B cut (i.e. Rodney Jerkins, Neptunes, etc), and you'll see not just a few but many flattened overs.

Yep, flat-out digital clips. And lots of 'em.

Many people, myself included, like the sound of those CDs. An argument can be made (and Steve MacMillan is making it) that the frequent, momentary clip and increased overall level can be more useful than compression/limiting alone in getting a torqued, punchy, contemporary sound.<HR></BLOCKQUOTE>



I'm not sure i'm following your point. When you look at a professionally mastered commercial CD waveform, yes there are many square waves, but on the player meters none of the commercial CD's i've ever made or seen actually clip. Are you talking about clipping while still in PT before the mastering?

Doug Ring
01-16-2002, 10:27 AM
I admit I'm still getting to grips with the process of making "loud CDs", and I don't dispute (though I dislike) the need to do it.

What I usually do is take time to play a mix through a master fader with no plugs and watch its metering for clips. Then I'll use volume automation to dip offending tracks by a few dBs for a brief instant. If I don't see any clips after that, I print the song. It usually comes out okay, but yeah - never as loud as Sheryl Crow! I don't think we should all panic over that, though - any of you guys ever put on a classical CD from time to time? (You out there, Nika?!) That's where you'll find dynamic range in spades.

When I've got a bunch of songs mixed down, I find Audiosuite's Gain program useful - highlight the song, open Gain and click "find peak". It tells you how far under, or even over, the file is. You can decide how much to boost, as well as cut, that peak level. Better than Normalise for allowing you to keep a quiet song quiet!

Mark Haliday
01-16-2002, 01:41 PM
>>>I admit I'm still getting to grips with the process of making "loud CDs", and I don't dispute (though I dislike) the need to do it. <<<

I know the feeling !

My solution for demo CD used to be L1+ and is now L2, usually limiting peaks from 2 to 9 dbs depending on the material. The nice thing about those plug-ins is that they won't change the mix the way a multiband compressor will, and it takes care of the dithering to 16 bit process as well.
It won't replace a proper mastering session, but to have people happy when listening back to their mixes in the car and at home, it is perfect.