Announcement: ATKAutoSwell 1.0.0

I’m happy to announce the release of a mono autoswell based on the Audio Toolkit. They are available on Windows and OS X (min. 10.8) in different formats.

This plugin applies a ratio to the global gain of a signal once it is higher than a given threshold. This means that contrary to a compressor where the power of the signal will never go lower than the threshold, for AutoSwell, it can.


The supported formats are:

  • VST2 (32bits/64bits on Windows, 64bits on OS X)
  • VST3 (32bits/64bits on Windows, 64bits on OS X)
  • Audio Unit (64bits, OS X)

Direct link for ATKAutoSwell.

The files as well as the previous plugins can be downloaded on SourceForge, as well as the source code.

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14 thoughts on “Announcement: ATKAutoSwell 1.0.0

  1. Thanks. Did a quick test playing long single note guitar (acoustic, electric and bass) samples and swelling part is there, but had some issue with initial transient (I think). There was a click everytime I play it (on start before gate/comp activates). Tried a lot of settings, click sound would change (lower or higher in frequency) but it was there. Maybe plugin needs lookahead time implemented? On the other hand maybe issue is on my end, any advice would be appreciated. Since delay(s) will be after this vst in my fx chain that click can easily build up

    1. Hi BojanB,
      There shouldn’t be a need for this, but I may have overlooked something. I didn’t here a click myself and all the filters that require the previous value are reseted when they should…
      Do you have the same issue witht he other dynamics plugins? What DAW and OS?

      1. Hi Matt,
        daw: vst host, I use it for testing. In previous test I used this chain: vstplayer free into atkautoswell. Loaded simple wav oneshots (from my sfz library). Windows 10. No, I usually dont have same issue.
        I think what happens is that note is played and gate (lets call it gate) from atkautoswell activates making swell but initial short transient somehow pass trough just a moment before swell is activated.
        Just saw notification about reply so instead of writing a novel I just shoot a video of my desktop so u can hear/see. This time I used as a source of sound dsk dynamic guitars vst (quicker than hooking up guitar) just to make sure if it isnt vstplayerfree somehow. Video:

        1. I’ll try to have a look at it this week-end. As the code is similar to the other dynamics plugin except for the gain curve (and it is continuous), I’m quite baffled (I’m also using VST Host on Windows 10!). I haven’t heard these clicks, but perhaps I should buy new ears as well. I’ll let you know.

          1. I’ve tested on my computer, but couldn’t reproduce the issue. Of course, at low attack and RMS time constants, the sounds is more hashed, but that’s to be expected :/

          2. Odd that you couldnt reproduce. I did few more tests to be on safe side. First same computer just Maschine as daw this time. Second, old laptop (different computer) with win7 and vst host x32 as host, dsk acoustic guitar x32 as sound source. In both results are the same as before, same as in video I uploaded. It just dont activate fast enough and let first transient trough. But, nevermind. Plugin was promising but shame I cant use it

          3. According to what you showed, you have the transient because you have a 10ms RMS power window and an attack of 10ms. That means that during these 20ms, before the computed “attacked” power is higher than the threshold, you won’t swell.
            If you put a power of 0ms (which is basically peak power, not average) and an attack of 0.1ms (the minimum value IIRC), you shouldn’t here the transient that much anymore.
            Any sorry, I should have checked the video link first!

  2. Hi, Matt-san

    I have an interest in your unique plugin, and test it on Logic Pro X(10.2.2).
    My system is the Mac OSX 10.9.5.

    Unfortunately, your ATKAutoSwell cannot be opened and the plugin manager gave me back the below info.

    validating Audio Unit ATKAutoSwell by MatthieuBrucher:

    AU Validation Tool
    Version: 1.6.1a1
    Copyright 2003-2013, Apple Inc. All Rights Reserved.
    Specify -h (-help) for command options

    VALIDATING AUDIO UNIT: ‘aufx’ – ‘u0yg’ – ‘MatB’
    Manufacturer String: MatthieuBrucher
    AudioUnit Name: ATKAutoSwell
    Component Version: 1.0.0 (0x10000)
    Component’s Bundle Version: 1.0.0

    * * PASS
    2016-05-18 12:35:06.023 auvaltool[66756:d07] Error loading /Library/Audio/Plug-Ins/Components/ATKAutoSwell.component/Contents/MacOS/ATKAutoSwell: dlopen(/Library/Audio/Plug-Ins/Components/ATKAutoSwell.component/Contents/MacOS/ATKAutoSwell, 262): Symbol not found: _AudioUnitGetProperty
    Referenced from: /Library/Audio/Plug-Ins/Components/ATKAutoSwell.component/Contents/MacOS/ATKAutoSwell
    Expected in: /System/Library/Frameworks/AudioToolbox.framework/Versions/A/AudioToolbox
    in /Library/Audio/Plug-Ins/Components/ATKAutoSwell.component/Contents/MacOS/ATKAutoSwell
    FATAL ERROR: OpenAComponent: result: -50,0xFFFFFFCE

    validation result: couldn’t be opened


    I hope this information contributes to your project!!!


    1. Hi Matt-san

      I add another info on Harrison Mixbus/Ardour.

      [ERROR]: Cannot get I/O configuration info for AU ATKAutoSwell


      1. Hi,

        I guess that if it can’t validate, it won’t play well in ardour as well :/
        Actually the thing is that I don’t have 10.9.5, I only have 10.11.4… It may well be that it can’t be compatible with 10.9 if I don’t have a specific option turned on. I’ll have to check this as well.
        Do you have the same behavior with the other plugins?

        1. Hi, Matt-san

          Ok, I have 10.11.4 although this is not my main system. And I’ll test the plugin and report you later.

          On 10.9.5, I tested ATK stereo limiter resulting in the fail as the same as AutoSwell.

          I checked Colored Compressor/Expander, and these plugins are working well!!


          1. Interesting… IIRC, I published the stereo limiter and the auto swell later than the colored compressor and expander. Which would explain the difference in compatibility then :/
            If you have XCode, you can always try to build them yourself to see if the behavior is the same or not.

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