Logic Pro and MainStage 64-bit mode FAQ

Logic Pro 9.1 and MainStage 2.1 can be used in 64-bit mode on Mac OS X v10.6.2 or later. Here are some frequently asked questions about using Logic Pro and MainStage in 64-bit mode.

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How do I use Logic Pro or MainStage in 64-bit mode?

You can switch between 32-bit and 64-bit mode following these steps:

  1. Quit Logic Pro or MainStage if it is running.
  2. Navigate to the Logic Pro or MainStage application in the Applications folder.
  3. Choose Get Info from the Finder File menu.
  4. Disable the option to "Open in 32-bit mode" to open in 64-bit mode.

    open in 32-bit mode option

What advantages are there to using 64-bit mode?

The main advantage is that you can address vast amounts of memory. With 64-bit mode, the application memory is not limited to 4GB as with 32-bit applications, so there is essentially no practical limit by today's standards. As a result, all the installed memory that is not needed by the OS is available for use by Logic Pro or MainStage and all the included plug-ins, which can be meaningful if your Mac has more than 4GB of memory installed. This larger amount of memory allows you to run far more instances of memory intensive plug-ins, such as sample-based software instruments.

Since EXS24 is memory intensive, should I be running Logic in 64-bit mode to get the number of instances I may need?

When running in 32-bit mode, EXS24 has an option to take advantage of an area of memory separate from the application's memory, allowing the number of EXS24 plug-ins and the amount of sample content that can be used to be quite substantial.

As a result, for most users, the benefit of 64-bit mode is realized when using third-party 64-bit native plug-ins that are memory intensive.

Do Logic Pro or MainStage perform better in 64-bit mode?

Logic's processing has always been highly optimized, so in most cases there are only nominal performance improvements when running in 64-bit mode, other than the ability to run more instances of third-party memory intensive plug-ins. However, since Mac OS X v10.6 Snow Leopard is highly optimized for 64-bit operation, there may be some performance gains in areas where Logic interacts with it.

Can I use my existing Audio Unit (AU) plug-ins in 64-bit mode?

To make the transition to 64-bit easier, both Logic Pro and MainStage are still able to access 32-bit-only Audio Unit plug-ins while in 64-bit mode by using a utility application called 32-bit Audio Unit Bridge. This application opens automatically whenever a 32-bit-only Audio Unit plug-in is accessed.* The 32-bit Audio Unit Bridge hosts all currently used 32-bit-only Audio Unit plug-ins and runs alongside Logic Pro or MainStage to provide access to the plug-ins being used.

The 32-bit Audio Unit Bridge has the same 4GB memory address limit as any other 32-bit application. Also, it is only possible to display and edit one 32-bit plug-in at a time.

Audio Unit plug-ins which are 32-bit only will appear in the channel strip plug-in insert menu under "Audio Units (32-bit)". Audio Unit plug-ins which are 64-bit will appear in the normal location in the menu. Check with your favorite third-party plug-in developers for updated information on the availability of 64-bit versions of their plug-ins.

Is there a performance penalty when using the 32-Bit Audio Unit Bridge?

32-bit Audio Bridge does use some of your computer's resources, but it is designed to operate extremely efficiently. In most cases, you should not notice any performance difference as compared to running the same plug-ins directly with Logic in 32-bit mode.

Should I disable Virtual Memory in the EXS24 when running Logic in 64-bit mode?

There are pros and cons to this, but in most cases it's best to leave Virtual Memory enabled. This ensures the shortest possible load times and avoids the potential of a major performance decrease in the event that there is not enough physical memory to hold all the samples in a project. If you have enough physical memory to hold all the samples for a project, you might see a nominal performance improvement if the EXS24 Virtual Memory feature is disabled, especially if the project has lots of audio tracks and relatively few EXS24 instruments.

Do Logic Pro or MainStage sound different in 64-bit mode?

There is no difference in sound quality between running in 32-bit or 64-bit mode. Prior versions of both applications have already used 64-bit processing resolution for plug-ins where it was felt there could be an audible benefit. In either mode, both Logic Pro and MainStage offer huge dynamic range and extremely high audio quality.

Is there a way to tell whether I'm in 64-bit mode?

Yes. Choose About Logic Pro or About MainStage from the respective application menus and the current mode will be displayed below the version number.

Learn more

* While most 32-bit plug-ins should work with the 32-bit Audio Unit Bridge solution, not all plug-ins may be compatible.

For more information about running Logic Pro in 64-bit mode, see this article.

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