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[Ashermusic]

I just had a "discussion" with a friend:)

I pointed out  to  him that virtually  every good  engineer I know recommends recording 24 bit at lower levels, i.e -12-018 dBs, for a number of reasons.

He says that  while he agrees that there is no loss when doing so he frequently records at hotter levels because if  you record it low, there  is only so much you can raise the playback level to i.e. send it out to a compressor and  really smack it without adding plugins, which change the math. So he says, as long as you understand gain structure fully, as he does, and depending on what you know you  want to do with it, it may be, and frequently is for him, a better idea  to record  it at -3 dBs rather than the  -6-18 range that  almost everyone else recommends.

It is not passing my smell test but he says it is because I do not really understand gain structure. I thought I did

Whaddya think?

[MoreSpaceEcho]

not buying it.

if you have something really low in level it's easy to just gain it up in the computer or somewhere in your analog realm.

tracking everything to -3 just makes no sense to me, you're going to have to turn everything down 10db just to be able to play back a tracking mix without clipping.

low levels+good monitoring+Cardinal Points

[jetbase]

Ashermusic wrote on Mon, 09 August 2010 11:37

I just had a "discussion" with a friend:) I pointed out  to  him that virtually  every good  engineer I know recommends recording 24 bit at lower levels, i.e -12-018 dBs, for a number of reasons. He says that  while he agrees that there is no loss when doing so he frequently records at hotter levels because if  you record it low, there  is only so much you can raise the playback level to i.e. send it out to a compressor and  really smack it without adding plugins, which change the math. So he says, as long as you understand gain structure fully, as he does, and depending on what you know you  want to do with it, it may be, and frequently is for him, a better idea  to record  it at -3 dBs rather than the  -6-18 range that  almost everyone else recommends. It is not passing my smell test but he says it is because I do not really understand gain structure. I thought I did Whaddya think?

Did he explain what it is about gain structure he thinks that you don't understand? Is there anything different from the usual multitrack recording/mixing that he is doing that may make recording at hotter levels a better idea?

[Geoff Emerick de Fake]

Ashermusic wrote on Sun, 08 August 2010 20:37

depending on what you know you  want to do with it, it may be, and frequently is for him, a better idea  to record  it at -3 dBs rather than the  -6-18 range that  almost everyone else recommends.

-6 on VU meters may be pretty close to -3 on peak-meters, depending on the source.

[tom eaton]

Geoff Emerick de Fake wrote on Mon, 09 August 2010 06:46

Ashermusic wrote on Sun, 08 August 2010 20:37   depending on what you know you  want to do with it, it may be, and frequently is for him, a better idea  to record  it at -3 dBs rather than the  -6-18 range that  almost everyone else recommends. -6 on VU meters may be pretty close to -3 on peak-meters, depending on the source.

I believe he's talking about peaking at -3dBFS.

Let's discuss.  If you run your converter at +24dBm = 0dBFS, which is -20dBFS = 0VU = +4dBm, and you like to peak around -3dBFS, that means an analog level peak of +21.  That's pretty hot.  Would easily overload some of my compressors (Drawmer 1968 clips at +20).  If you have a particular track that you want to hit a particular compressor that hot, go for it... that's the spirit of "whatever works."  But as a general practice, I think it's a bad idea.

If you run your converters -16dBFS=0VU... well, then you're talking about a -3dBFS peak of +17 in the analog world.  Certainly generally usable.  Unlikely you'd clip any real piece of analog gear there.

So sure, if he knows that he wants to go d/a to a particular piece of gear kind of hot, why not?  The less manipulation between the a/d and the d/a the better as far as I'm concerned.

tom

[Ashermusic]

Well this  whole episode  has shown me  that I have a lot to learn still. The issue is apparently  not  as black and  white as I believed.

I reached out to some  engineers I know who have done some major work and while some agreed that lower levels on the way in are a better  choice most said "it depends."  Here are  some excerpts from their responses:

"In practice, I tend to record transient-rich material as hot as I can since but am careful to not use any peak limiters 'to tape' unless I'm very sure what they are doing.  I don't get overly concerned if I see some overs in the drum tracks.  On the other hand I am more careful with things like vocals and other instruments since by the time you are seeing overs for those types of instruments you are likely to be getting distortion also.  And more importantly, not good distortion.  That is not to say that I purposefully record them at a low level although I know people that do and they swear it makes a big difference.  I just tend to prefer the sound of a mic pre working a little harder which usually means I'm hitting the A/D converter with plenty of level.  "

"Certain converters, ESPECIALLY older ones, such as the Digidesign 888|16 and 888|24, as well as consumer grade ones, which do in fact distort BEFORE the red L.E.D. indicator lights up. This is because they ANALOGUE section of the converters were subpar, and you could actualy hear and measure the distortion. SO tkeeping the signal well below that -3dB was a safe thing to do. I would do it IF I was using older digital equipment. BUT the new generation (Pro Tools HD, Apogee Symphony, Rosetta, Motu mk3s, etc.) do NOT have that issue. They have figured out how to not distort their analogue section before the digital one distorts. So now, if using a newer converter, you can in fact record up to -0.5 dBFS if you like, without that analogue distortion ocurring anymore."

"In my opinion, there is nothing wrong about hitting the converters on the way IN as high up as -3dB. This is still conservative enough to be useable, since no distortion will occur. Yoiu should however do a simple input test and measure where YOUR particular hardware distorts. Does it distort BEFORE the red LED? at the same time as the red LED? If I were you, when you have time, measure that, and label it right on your converter, for easy reference always."

[KB_S1]

A big part of the issue (to me) is what happens to the signal levels once they are in the DAW.
Forget the issue of convertors altogether for now.

If you have 40 channels of audio: all at -0.5dbfs: there will be mix bus issues.
Also consider any plug-ins that are to be used (if you use them).

If a process you want to use involves boosting a signal, you will first need to attenuate the signal, then process it.

[Geoff Emerick de Fake]

tom eaton wrote on Mon, 09 August 2010 21:02

Geoff Emerick de Fake wrote on Mon, 09 August 2010 06:46 Ashermusic wrote on Sun, 08 August 2010 20:37   depending on what you know you  want to do with it, it may be, and frequently is for him, a better idea  to record  it at -3 dBs rather than the  -6-18 range that  almost everyone else recommends. -6 on VU meters may be pretty close to -3 on peak-meters, depending on the source. I believe he's talking about peaking at -3dBFS. Let's discuss.  If you run your converter at +24dBm = 0dBFS, which is -20dBFS = 0VU = +4dBm, and you like to peak around -3dBFS, that means an analog level peak of +21.  That's pretty hot.  Would easily overload some of my compressors (Drawmer 1968 clips at +20).  If you have a particular track that you want to hit a particular compressor that hot, go for it... that's the spirit of "whatever works."  But as a general practice, I think it's a bad idea. If you run your converters -16dBFS=0VU... well, then you're talking about a -3dBFS peak of +17 in the analog world.  Certainly generally usable.  Unlikely you'd clip any real piece of analog gear there.

That's what happens if you use VU meters on signal such as claves, which have 20dB+ crest factor. If you want to have the meters showing just a little something (let's say -10VU), the average level is -6dBu, but the peak level is +14dBu. If your D/A is calibrated at 0dBfs=+18dBu, your peaks will be at -4dBfs, and actually they maybe just 6dB below hard clipping in the analog domain.
Nobody ever mentioned tracking claves at 6dB below clipping being malpractice, but tracking them at -4dBfs is considered anathem.
The essence of my concern is that many people consider the last 12dB of headroom in a digital system to be a forbidden zone, but they accept without a second thought running their analog gear in the last 6dB of headroom.
In fact, I believe they have figured out tracking at lower level is beneficial, but they attribute this to some flaw of the digital domain, when in fact it is mainly an analog concern.

[Geoff Emerick de Fake]

KB_S1 wrote on Tue, 10 August 2010 10:49

A big part of the issue (to me) is what happens to the signal levels once they are in the DAW. Forget the issue of convertors altogether for now. If you have 40 channels of audio: all at -0.5dbfs: there will be mix bus issues.

No. There may be issues, but the culprit is not overloading the mix engine, whether PT's 48bit fixed, where each signal is attenuated by 54dB before reaching the MCU, or 390dB in any 32bit float (needless to say this is done without loss of resolution).
You could write that differently and say that PT's internal maximum operating level is +54dBfs and Samplitude/Logic/Reaper is +390dBfs.
Typically, a signal at -0.1dBfs, with 20dB of boost and 10dB gain-make-up and fader at +10 will still be far from digital clipping.

Quote:

Also consider any plug-ins that are to be used (if you use them). If a process you want to use involves boosting a signal, you will first need to attenuate the signal, then process it.

That's what most plug-ins do; only a restricted number of maverick plug-ins still exhibit problems of this sort.

[tom eaton]

Hey Jean Luc-

A page or two ago on this very thread you'll find me suggesting folks use the Dorrough meters for this very reason.  Not only can you see average and peak levels simultaneously, you can look at the dynamic range of your signal (and with the digital meter you can see your absolute headroom as well!).  Great for tracking, mixing, mastering...

I was not referring to a VU meter (which is not interested in peaks anyway) in this last post, but rather to a calibration standard when interfacing with the analog world.

Percussion might be the exception to every "level practice" rule, as no "average" signal exists at all.  Strike one clave with the other, the signal peaks and is gone.  In those cases of course it is all about peak management!

tom

[Geoff Emerick de Fake]

tom eaton wrote on Tue, 10 August 2010 14:16

Hey Jean Luc- A page or two ago on this very thread you'll find me suggesting folks use the Dorrough meters for this very reason.  Not only can you see average and peak levels simultaneously, you can look at the dynamic range of your signal (and with the digital meter you can see your absolute headroom as well!).  Great for tracking, mixing, mastering...

I must admit I'm somewhat spoilt by Samplitude, which offers me a vitual Dorrough meter while tracking.

[Bob Olhsson]

Amazing how people listen with their eyes today!

If you break out an audio oscillator, feed it into all of your own A to D inputs at once so as to place maximum stress on the converter power supply and then sweep different frequencies and levels, you can hear which converters have enough headroom and which don't. An IM distortion test is even more revealing.

If you haven't actually done this, aka your homework, don't make assumptions about level capabilities.

[thedoc]

And you can de-rattle your room at the same time.

[organica]

Bob Olhsson wrote on Wed, 18 August 2010 14:59

Amazing how people listen with their eyes today!

label guy today told me;
"The mix is so much better now.
Bring down all vibes, harp and mellotron being used as accompaniment, in the mix, by about 5%."
When this adjustment is made , it'll be a  calculated numeric measurement and afterward if it doesn't sound bad, that's what they'll get.

<If you break out an audio oscillator, feed it into all of your own A to D inputs at once so as to place maximum stress on the converter power supply and then sweep different frequencies and levels, you can hear which converters have enough headroom and which don't. An IM distortion test is even more revealing.>
Must do this.

[phantom309]

organica recording wrote on Fri, 20 August 2010 23:08

<If you break out an audio oscillator, feed it into all of your own A to D inputs at once so as to place maximum stress on the converter power supply and then sweep different frequencies and levels, you can hear which converters have enough headroom and which don't. An IM distortion test is even more revealing.> Must do this.

That's a damned good idea. I'm going to try this with the 3 I/Os we have in here.