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A Brief On The Use Of VCA Masters in a ProTools HD session

Discussion in 'Recording' started by Davedog, Jul 17, 2015.

  1. Davedog

    Davedog Distinguished Member

    Dec 10, 2001
    Pacific NW
    I borrowed this from the DUC. I hope it makes more sense than I do at explaining things. YMMV as does each DAW. I do NOT mean this as a directive to send anyone towards ProTools as a choice of their DAW. Since this method was taught to me it has opened up my mixes and made my work flow somewhat easier with drastic results. My point in the other discussion was more about results rather than what tool I was getting the results on. I have looked at screen captures of several different DAW programs and haven't found any of them that seem to have this function available. I do not think this a 'workaround' predicated by some lack on PT's part. It is functionality which comes from the automation and mix features on different high-end consoles...SSL in particular...and I believe was developed because of that. This function began at v.7.2 in HD.

    So whatever evil policies and lacks PT has had or does have...believe me...I live with it every day and its not without bugs and its oddities...this particular function is not one of its abnormalities. I DO NOT MEAN THIS AS A COMPARATIVE post.....Enjoy....

    Original post by Jonathan Wales that helped me out a lot......
    There are some real world examples.

    I hope it's cool with the OP...............

    Hi Guys,

    Alright now that this thread has got to this stage, let me weigh in on some of the statements / comments that have been made and try to give some real clarity to this.

    The implementation of VCA control in ProTools has been done in a very clever way, but to truly understand this it is essential to grasp some of the other underlying changes that have been made to groups in the process. I will try to set out some of this here.

    First, let's go back in time a little. If you imagine the way that mix groups used to behave in ProTools, they allowed the faders to be linked to each other. In that situation if you picked up one fader, all the others would follow at the same time in relation. However there were two primary problems with this. Firstly it was difficult to move one fader in relation to another (you had to do the whole "declutching" thing) and secondly ProTools was not aware of the relative positions of the faders if you moved them all to an end stop. Try it in old protools - if you group faders together in a mix group and set different positions, then pick up the one with the lowest level and move it to the top of its travel......when you move it down, all the faders are back in a straight line.

    One of the major improvements in 7.2 is that this problem has been eliminated. ProTools is now capable of remembering the relative positions of faders, even after they all hit the end stop. if you wanted to try the same test in 7.2, you would create a mix group and check the button to link the faders. Set some different levels and pick up one of the faders. Move the lowest fader to the top of its travel. They all end up at the same level, BUT when you move it down again, the relative levels are preserved.

    So this was the first headache that has been solved. The good news is that now we can link pans in groups as wel, they are able to behave the same way - i.e. if pans are linked together and have relatively different values, then those will also be preserved even if you hit and end stop!

    Having explained this, let's look at the whole VCA concept in ProTools.

    The basic idea is that you have the ability to exert control over a ProTools group with a fader. The ONLY thing that this fader will do is allow you to change the volume of all the tracks in the group as a block. It will also allow soloing and muting (and record arming and input status) for the tracks in the group, BUT THAT'S IT.

    Yes panning can now be linked between tracks in the group, but this is a separate issue from whether or not the group is controlled by a VCA master fader.

    So the classic mixing use of VCA faders is possible in ProTools:

    1) create a group
    2) Make sure that the faders in the group are NOT linked within the group itself
    3) Create a VCA master track
    4) select the name of the group you just created from the output pane in the mix window on the VCA master track (or select the VCA master in the appropriate place in the groups window either at the point of creation, or by doing a modify groups command)

    Once this relationship is established, moving the master fader will cause faders in the group to move. If the faders in the group have different levels relative to each other, then they will be affected by the position of the VCA in the way you would expect - i.e. if the VCA master is at -10dB, then each fader in the group would be 10dB lower than its position would be if the master was at 0.

    Now comes the interesting part:

    The complicated portion of this type of mixing comes when you want to do crazy things like change the position of the slave fader WHILE you are moving the master, or you want to examine what happens when the master fader is fully down at -infinity.

    This is where any analogies with the original VCA systems are no longer correct, and why the system in ProTools is referred to as a VCA-STYLE system. From this point on, the system in ProTools has more in common with "gangs" in a Neve environment than any other.

    Let me explain.

    In a traditional VCA system (SSL being the one every mixer thinks of), the level of the VCA directly affected the level of the fader in an additive way. This means that once the VCA master is all the way down there is no possibility of hearing output from a slave fader. Whilst this makes sense on one level, it has proven to have many restrictions in practise the biggest being that as the VCA master is lowered, the position of the slave fader no longer bears any relationship to its audio output level. In this respect this old behavior is the same as using an aux in protools.

    If you imagine the situation with using an aux bus, you are sending the audio signal output from the faders through an aux before you hear it. Thus if the aux is at -infinity (i.e.off) you could have the fader at +12dB and you would never hear anything. This is the same with a traditional VCA.

    The problem is that it is very difficult to do meaningful work with the slave faders in this situation because their dynamic range is truncated by the position of the aux (i.e. if the aux is at -40, you could never get anything louder than -28 out of that signal path (a slave fader at +12 feeding into the aux). It is also a problem because if you are looking on a control surface (or on the mix window) at a slave fader but are unable to see the master, you have no possible idea of what actual level of audio will be coming out at any time.


    The primary rule which applies in the VCA-style system used in ProTools is that the audio output level from a track is ALWAYS indicated by the position of the fader. Even when it is controlled through a VCA mster.

    There is also no restriction on the possible offset between a slave and a master. Thus it is possible to have a track in a group controlled by a VCA master, pull the VCA master all the way down, push the slave all the way up and.......you will hear the slave fader at full level.

    Now this is an extreme example, but it allows for some important mixing techniques that are almost impossible any other way.

    Think for example about an orchestra. You have lots of mics set up. Some are the general "tree" mics that capture the orchestra as a whole, some are spot mics to get "close-ups" on individual instruments etc.

    Using the new protools grouping and VCA masters, you could do the following example:

    The mics for the tree would be members of one group, controlled by the TREE master (from this point on, the word master refers to VCA master)

    The string mics are controlled by the STRING master.

    The choir mics are controlled by the CHOIR master, winds by the WIND MASTER, etc.etc

    Now you can take each of the masters (TREE, CHOIR, WIND, BRASS, PERC, etc) and create a mix group containing them.

    Now this can be controlled by the MUSIC master.

    Starting to see some power now?

    Now take this one example. Imagine that there are two "room" mics that are in the tree group, and that at the end of this one piece of music, it would be great to have everything else fade out, but keep those mics up so that the natural reverb tails from the room are heard as long as possible.

    If all these things were going through auxes, that would be difficult.

    In this situation, no problem.

    As you get towards the end of the piece, simply put the 2 room mic tracks into a writing condition (either WR, or writing in latch).
    Fade down the master MUSIC fader.

    Everything fades out EXCEPT the two tracks which are writing stay still, because the rule says that the position of the fader IS the audio level, and because the tracks are writing they wont move.

    Now that starts to get truly useful.

    Of course you can still set up auxes and have the outputs of the individual sections of the mix feed into the auxes so that you can do global EQ etc...... but this new feature gives you a whole new set of tools.

    Don't forget that you can also link together plugins of the same type on the same level (i.e. same horizontal position in the mix window), so that changes made to one are made to all the others simultaneously.

    Don't also forget that the grouping in protools is dynamic. This means that you can go into modify groups, link something (pan, send eq or whatever), make an automation move, go back to modify groups, unlink it.

    The move will still be there, because the automation was written to the tracks in the group, but that parameter (pan, send eq or whatever) is no longer linked so automation can once again be done on individual tracks to tweak them.

    Powerful stuff.

    Also, remember that ProTools allows faders to be members of more than one group. Consider this:

    You make a group containing all of the woodwinds. This is controlled by the WIND vca master.

    However, it sucks that the oboes are too edgy. There are 2 different oboes, each with their own mic (unlikely but this is an example). You could create another group just containing the oboe tracks. Link the EQ between them. Then as you adjust one, the other follows. This doesn't change the fact the the levels are still subject to the VCA master control set up from the first group...........

    Are you starting to get an idea of just how powerful this all is...........

    Use it. Trust me, you will be amazed at the things you can do!

    Jonathan Wales
    Sonic Magic Studios
    Culver City CA

    There is a very fine explanation of the use of vca masters in an older Sound-on-sound article.
  2. DonnyThompson

    DonnyThompson Moderator (Distinguished Member) Resource Member

    Nov 25, 2012
    Akron/Cleveland, OH
    Home Page:
    Good post, Dave. While I'm not a PT guy, I still appreciate you taking the time to post this for those here on RO who are using PT as their production platform.
    TheJackAttack likes this.

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