To finish of this Getting To Grips With Pro Tools series on taking your first steps in Pro Tools here are two useful tips. We are not going to how to mix in this series, there is plenty of content on the site about that. However, in the first part of this last part, we are going to look at the thorny issue of headroom on the mix bus and the second tip is a look at a rarely seen part of Pro Tools, the Disk Allocation window.
Mixing And Headroom
How many times have you been mixing a track and found that as you progressively push the levels up you end up hitting digital headroom on the Master Fader and so you have had to bring the individual track levels down which is never that easy especially if you have started adding automation.
So here is the trick. When you start mixing a track push the Master Fader up to +6dB so that when you start seeing the Clip lights flash on the master all you need to do is bring down the Master fader until it stops clipping so as long as you don’t end up much below 0dB you will be fine.
Why Have A Master Fader?
The point of a master fader is to monitor headroom in your system. Headroom is something I feel strongly about. Considering how well current digital systems perform there is no excuse for clipping but every day I see people unintentionally ruin their audio by clipping it because they didn’t use a master fader.
It was perilously easy to unintentionally clip audio when using Pro Tools 10 and earlier, especially using TDM. TDM is a fixed-point system as opposed to the floating-point system used in Native systems. In Native versions of Pro Tools 10 and earlier things were more forgiving but since Pro Tools 11, Native and HDX systems are both floating-point and with far greater bit depth than before throughout the application. This means that dynamic range is potentially almost unlimited but in spite of this, monitoring the headroom is just as important as it always was and the way to do this is using a master fader.
All Sessions Should Have A Master Fader
Although you might never touch it, your session should have a master fader - Why? The most important thing to realise about master faders is that the really important bit is the meter. That is why you are creating it in the first place, you might use the insert slots, you might use the fader but you will always use the meter and you need that meter!
Master Faders are created by the system at summing points in the mixer. Fundamentally the job of a mixer, whether hardware or software, is to combine (i.e. “mix”) signals together. A summing point is a place in the mixer’s signal path where this combining happens. If two signals are combined together there will be a new total value to represent the mixed signal - a voltage in an analogue mixer, a number in a digital system. This value will usually be greater than either of the incoming signals. So generally the more signals you combine, the greater the total output becomes.
As total summed output tends to increase the more tracks you combine, and also because many inexperienced mixers tend to turn up the quiet thing rather than turn down the loud thing when balancing tracks, it is not unusual to run out of headroom.
In this example, I have created a session with 10 mono audio tracks. I created a -20dB 1KHz sine wave on these tracks. In this case, mono is simpler as it avoids considering a mixer’s panning law. I then created a mono master fader and assigned it to the same output as the audio tracks and then option clicked the mute button of one of the audio tracks to mute all.
Problem Solving - Disk Allocation
Remember to check Disk Allocation. For reasons I have never been able to get to the bottom of Pro Tools can sometimes change the Disk Allocation settings to another hard drive on your system, although it seems to handle much less on later versions of Pro Tools, so maybe Avid has nailed this one.
Disk Allocation is a setting within Pro Tools that determines which hard drive any content on a track will be recorded onto. It is there because once you get beyond 24 or so tracks you need to be considering spreading your tracks across multiple hard drives if you want to keep Pro Tools happy. Yes I know you can have sessions with more than 24 tracks on one drive and get away with it, I have done it too on many occasions but the guidelines rightly say that once you get above 24 tracks you should be looking at more than one hard drive especially if your tracks are heavily edited.
So let's take a look at the Disk Allocation window. You get to this window from the Setup menu.
The Disk Allocation window takes the form of a table with two columns, the first lists each track in your session and the second shows where on your system any audio files recorded on that track will be saved. Normally as above, all the tracks in the Root Media Folder column should be set to the session folder on your external drive, in my case Work Disk 1 and the session folder “Meet the Patels”. However, there are times when these settings are not correct. The classic scenario when Disk Allocation will be wrong is when you have copied a session folder from one drive to another. When you open the session on the new drive you should always go into Disk Allocation and change the Root Media Folder settings to the new drive location, as Pro Tools won’t do this for you. It still thinks the session is still on the old drive. You can do this by click and holding on the arrows at the right hand end of the Root Media Folder for that track and a contextual menu will come up.
The menu will contain all the drives that Pro Tools can record onto. Simply select the desired drive and it will change to that drive. You can change all of the tracks at once by holding down the Alt and clicking any track. Notice that all the tracks will be selected so that whatever you select on one will then be implemented on all the tracks.
It also seems that sometimes when you create a new track Disk Allocation can be set to another drive. I have wondered whether this has had anything to do with where on my system I have just been, say to import some audio, but I have never been able to nail it down, so the advice is to be aware and regularly check that Disk Allocation is set correctly.
Another tell-tale sign that disk allocation is not set correctly is that if you find a session folder on another drive which doesn’t have a Pro Tools session in it but does have either and/or an audio files or fade files folders in it.
We Come To The End
Well, that is it. We have come to the end of this Getting To Grips With Pro Tools Series. Whether you are a beginner or a seasoned Pro Tools user I hope that this series has been helpful for you.