Please Define VCA and DCA

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This topic contains 9 replies, has 6 voices, and was last updated by Profile photo of airickess airickess 2 years, 8 months ago.

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  • #50489
    Profile photo of Em
    Em
    Participant

    Geez, I’m a real newb but I see these and don’t have a clue what they stand for…
    Thanks!

    #50490
    Profile photo of Andreas
    Andreas
    Moderator

    From Users Guide, Chapter 8.11 “Mute and DCA Groups”:

    DCA Groups – A DCA (Digitally Controlled Attenuator) provides remote control of the levels of the channels assigned to it. Unlike a stereo Group, audio does not pass through a DCA Group. Instead, the audio levels are controlled at the channels by information sent from the DCA master.

    The DCA master Fader adjusts the level of assigned channels at their channel fader point and before the Pan control. This means that post-fade levels to the LR mix and effects are adjusted. Pre-fade monitor sends are not affected. The fader adjusts from fully off to +10dB boost. A channel can have a maximum +10dB boost including its own fader and control from any assigned DCA group faders. When a DCA fader is at its ‘0’ position it has no effect on the channel levels. This is the typical starting point when working with DCA Groups.

    A VCA would be a Voltage Controlled Attenuator, used in analogue desks for similar functionality.

    #50500
    Profile photo of MJCElectronics
    MJCElectronics
    Participant

    In the large format analogue days A&H used to publish a guide called “Mixing Live with VCAs” that I would point people to for a good explanation, but since the ML series was discontinued they seem to have pulled that document from the web site.

    It’s a shame because it gave a good explanation of VCAs for the uninitiated, and is equally applicable to DCAs in the new digital world.

    To Carey D. – Any chance you can get it republished? Even as-is it’s a really useful guide, and it probably wouldn’t take too much work to be rewritten for the digital age.

    In the absence of that there’s still a VCA guide for the ML3000 at http://www.allen-heath.com/media/ML3000-VCA-Groups-Application-Guide.pdf which has some of the explanations although it is specifically aimed at the ML3k so the detail won’t apply to dlive/iLive/GLD/QU

    #50501
    Profile photo of Em
    Em
    Participant

    WoW!
    Thank you all for such great info!
    Fumbling my way through, but this stuff is intriguing, fun, and rewarding!
    Thanks again for sharing your knowledge !

    #50502
    Profile photo of MJCElectronics
    MJCElectronics
    Participant

    I edited my reply above but just noticed it didn’t submit.
    Have a look at the link, it might help.

    #50503
    Profile photo of Em
    Em
    Participant

    Thank you! Great resource! Are you mixing live and or studio? Are you using this option a lot?

    #50504
    Profile photo of [XAP]Bob
    [XAP]Bob
    Participant

    My work is basically live, and I use DCAs for obviously grouped instruments – Drums being the prime example. That allows me to build a custome layer with the drums on one fader, leaving space for FX returns etc.

    #50506
    Profile photo of MJCElectronics
    MJCElectronics
    Participant

    All live for me too, never done the studio thing.
    There’s loads of great tricks you can do with DCAs.
    I generally assign one to all vocal channels and one for everything but vocals (labelled EBV), lets you get a quick “vocals on top” balance with just 2 faders.
    Just remember your DCA is like a remote control for the channel faders of every channel that it’s assigned to, so your post-fade aux levels will ride with it as well. That’s usually what you want, ride the vocals DCA and the vocal effects sends ride with it keeping the balance correct.

    #78189
    Profile photo of tablatom
    tablatom
    Participant

    MJCElectronics old thread, but I have just started using DCA’s and I really like your EBV on one fader and ONLY V fader idea.
    I do this manually, so this is going to be great.
    QUESTION.
    So by moving the DCA fader, does that that mean that the inputs assigned to it, their send values to the aux busses (mix 1 – 7) are changed in proportion too?
    This would be great.
    Thanks Tom.

    #78211
    Profile photo of airickess
    airickess
    Participant

    So by moving the DCA fader, does that that mean that the inputs assigned to it, their send values to the aux busses (mix 1 – 7) are changed in proportion too?

    Only if those inputs are set to Post Fade for each of the Mixes. If they are set to Pre Fade then the DCA will have no effect on the sends to any output except L/R.

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