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Instant A/B Switching in Logic Pro…How?

Last night, a good friend of mine asked me this: “Hey, I had this track mastered by two different engineers, I want to load them up in Logic Pro to compare the two versions. I want to be able to A/B switch between those tracks in real time, with just one click.”

Good question. In Logic Pro, soloing regions isn’t instant, and soloing tracks requires two clicks. I couldn’t think of another way than to chop up the second region and put some chops on the first, or to put the two versions inside a Take Folder and switch between versions by comping. That works fine, but doesn’t this call for a simple solution in Environment? All we really need is to invert the ‘polarity’ of switch one (the solo button) and pass that data on to switch two. Setting this up in Logic Pro is easy.

A/B Switching: Logic Pro Environment

logic pro environment window

building an A/B switch

All I did was connect a monitor object to track ‘Version A’ to be able to tell what message gets sent out when the solo button is pressed. The monitor object is connected to the Transformer Object, and the Transformer Object is connected to track ‘Version B’.

A/B Switching: Transformer Object

logic pro transformer object

I chose to map a value of 0 to 1 and a value of 1 to 0. Without specifying any conditions, the mute button works the same way. The fader, panpot and sends are now all ‘connected’. In case you don’t want this, narrow down the conditions of the Transformer Object and change its Mode:

logic pro transformer object

Brilliant update: Here’s Bob Kickflip’s approach (see below in the comment section):

I have a more straightforward way, which doesn’t need any Environment work. You need two audio tracks. Put the two files to A/B test on them. One the first channel, set it to no output. On the second, insert a Noise Gate on one of the channels, and set the sidechain input to the first audio track. Now to a/b between them, you just need to click the ‘Monitor’ button.

Booyah!

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  • fatman

    Just option-click the solo button of the track you want to hear.  Instantaneous.  One click.

    • Fatman,

      🙂 

      yes, but… that’s a click, a modifier key, and a hover. 

      Cheers 

  • Bob Kickflip

    Interesting, but I have a more straightforward way, which doesn’t need any Environment work.

    You need two audio tracks. Put the two files to a/b test on them
    One the first channel, set it to no output.
    On the second, insert a Noise Gate on one of the channels, and set the sidechain input to the first audio track.

    Now to a/b between them, you just need to click the ‘Monitor’ button. 🙂

    • Bob,

      You nailed it. Added this to the post.

      Cheers!

      • Bob Kickflip

        Hey there, just saw your reply, thanks for adding the info 🙂
        Great to be able to contribute a tip to such a good blog!

        • Out of the box thinking like that deserves an edit! Cheers.

          • Bob Kickflip

            I’ve been using it a lot more lately in the mixdown stage too – having the compressor on the main output and level matching the reference track makes for a very smooth and quick way to compare. Especially if you have your screensets set up so that the main output channel is always visible 🙂

          • Dan

            Bob, thank you so much for your contribution! I realize this is a year old, but can you elaborate on how you would set this up to a/b between your master and a stereo audio reference?

    • Ethan Shoemaker

       I ran into one issue with this solution. When you have a multimeter on the main output channel, view the Goniometer. When you enable monitor on the noise gate (to listen to track A), the Goniometer goes straight center. But if you look at the goniometer for each individual track, both tracks have a nice stereo spread. Any ideas why? Could it just be my mix? Let me know if either of you ran into this as well or if its just me.

  • mindprint

    Or, if you have more than 2 tracks to compare (A/B/C):

    * put them on 3 different tracks
    * selct them all and choose “Pack Take Folder” (^+CMD+F)
    * Then just double click the take folder
    * now with mouse just click on the corresponding track you want to listen

    • mindprint, yes man, very creative! It’s just a shame that changes in a comp aren’t reflected immediately while Logic Pro is running. Something I hope Apple will address in a future update, or in Logic Pro X. Thanks!

      • mindprint

        Yeah it’s a drag that it takes a moment to switch, could be the buffer size. 

        Anyway, just ran into your blog today. Great site and wonderful and useful content.
        Thank you

        • mindprint, great to hear that! Thanks.

  • Rombazomba

    Or … get 1 Track Solo, hold Alt and click the other “Solo”-Button from the other Track. Viloa! Even works when switching from multiple Solo to one solo track. Alt-click on solo makes single solo

  • Grandweird0

    Nice! Works like a charm for A/B-ing my mixbus and my reference-track. Thanks for that! Is there a way to toggle the compare button with a key-command? I just could not figuere out how…

    Great Blog, Dansky! Thanks for sharing Your knowledge

    • Thank @089477476fe8595c76e2e899ced04df3:disqus … Hmmm I’m not sure if you can toggle that with a Key Command. A MIDI note or CC button shouldn’t be much of a hassle to set up. Cheers.

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