You can install Audio Units plug-ins from manufacturers other than Apple to process audio in Logic Pro, GarageBand, and Final Cut Pro. When installed, Audio Units plug-ins appear as individual components in the Library folders on your Mac:

In the Finder choose Go > Go to Folder, enter '/Library/Audio/Plug-Ins/Components' into the Go to Folder field, then click Go.
You can also check the Library in your Home folder. In the Finder choose Go > Go to Folder, enter '~/Library/Audio/Plug-Ins/Components' into the Go to Folder field, then click Go.

The latest versions of most DAWs are 64-bit only (Logic Pro X, Pro Tools 11) or ship with installers for both 32-bit and 64-bit versions (Ableton Live 9). Other differences aside, a 64-bit digital audio workstation is only able to load 64-bit plugins and 32-bit digital audio workstation are only able to load 32-bit plugins.
Instructions Step 1 Download the VST to RTAS Adapter pack. Remember to match the adapter with your version of Pro Tools. Step 2 Click on the VST to RTAS.
VST and AudioUnits (AU) are the two native plugin formats for Mac OS X. Although there are other DAW specific formats for plugins, VST and AudioUnits are more common and compatible across various DAWs like Cubase, Logic, etc. There is an abundance of VST and AU plugins for expanding your DAW and building your collection of effects.

How To Use Vst Plugins In Logic Pro 9 64-bit

How To Use Vst Plugins In Logic Pro 9.1

Built-in effects and instruments included with Apple apps like Logic Pro, GarageBand, MainStage, and Final Cut Pro don't appear in the Library folders and can't be removed manually.

Choose Logic Pro Preferences Plug-in Manager, or MainStage Preferences Plug-in Manager. In the Plug-in Manager, locate the plug-in. To filter the list by manufacturer, click the manufacturer's name in the left column. If the plug-in doesn't appear in the Plug-In Manager, find the plug-in file.

How To Use Vst Plugins In Logic Pro 9 64-bit

How To Use Vst Plugins In Logic Pro 9.1

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