What are AU and VST audio plugins?

ByMunyaradzi Mafaro

AU and VST are two different kinds of audio plug-ins used in music production. Audio plug-ins are small pieces of software that can be added to a digital audio workstation (DAW) to change the sound of an audio track.

AU stands for Audio Units. It is an Apple plug-in format that only works on Mac computers.

VST stands for Virtual Studio Technology. It is a plug-in format made by Steinberg that can be used on Mac and Windows computers.

Both AU and VST plug-ins do similar things. They can be virtual instruments, like a piano or drum machine you play using a MIDI keyboard. They can also be audio effects that change how a recording sounds, like adding reverb to make it sound like the music is in a big room.

How AU and VST are similar

AU and VST have much in common since they are audio plug-in formats. Here are the main things that make them similar:

  • Both can be virtual instruments or effects
  • Both get added to tracks in a DAW to shape the sound
  • Both have simple user interfaces with knobs, sliders, and buttons
  • Both come in free and paid versions from many different companies
  • Both can be used in any major DAW like Logic, Ableton, FL Studio, etc.
  • Both can accept MIDI input to play virtual instruments
  • Both process audio in real time with low latency
  • Both can be automated to change settings over time

So, AU and VST plug-ins provide the same basic functionality for day-to-day use and aren’t that different. The biggest difference is that AU only works on Mac, while VST works on Mac and PC.

Advantages of AU plug-ins

Even though AU and VST have a lot in common, there are a few reasons some people, especially Mac users, prefer the AU format:

Better performance on Mac

Since Apple made AU for Mac computers, AU plug-ins are good at taking advantage of how Mac handles audio. They tend to use less CPU power than VSTs.

This is a big deal if you use a lot of plug-ins at the same time. With AU, you’re less likely to get audio crackles and pops when you have a project with many tracks and plug-ins. Your Mac can handle more AUs than VSTs before the audio messes up.

Smoother automation

Another Way AU plug-ins work better with Mac is automation. Automation lets you change plug-in settings over time, like having the track get quieter or adding more reverb in specific sections.

With AU, you can set up detailed automation that plays back the same way every time. The plug-in handles the automation directly. VST automation on Mac sometimes doesn’t play back the same way and can cause little glitches. The DAW has to tell the plug-in what to do instead of doing it.

Easier to manage

Apple has stricter rules about how AU plug-ins are installed and work under the hood, which makes them easier to organize.

All your AU plug-ins are put in one folder on your Mac. In the DAW, you can see all your AU plug-ins. You can delete it from the AU folder if you no longer need it.

VST doesn’t have a standard place to put the plug-in files on Mac. Different VSTs get installed in other areas, making it harder to keep track of and delete them later.

Works better with Logic Pro

If you use Logic Pro, Apple’s professional DAW, using AU plug-ins makes things easier. Logic scans for AUs automatically and adds them right away.

To use VSTs in Logic, you must tell it which folder they are in. Sometimes, you have to restart Logic for it to see new VSTs. AU is more convenient in Logic.

Advantages of VST plug-ins

While AU has some benefits on Mac, there are still a lot of good reasons to use the VST format:

Works on both Mac and PC

The biggest advantage of VST is that it works on almost any computer, while AU only works on Macs. If you work with people who use PCs or switch between Mac and PC yourself, VST is the way to go.

Imagine you have a big music project with lots of plug-ins. If you save it as an AU project, people can only open it on a Mac. If you save it as a VST project, anyone can open it, and all the plug-ins will load fine. VST is better for compatibility.

More plug-ins available

Another big advantage of VST is that there are way more VST plug-ins than AU plug-ins. Almost every audio software company makes VST versions of their plug-ins, but not all of them bother making AU versions.

This means you have a much wider variety of virtual instruments and effects in VST format. Chances are, if you’re looking for a specific guitar amp sim or a unique reverb effect, you’ll find it in VST format.

Supports more advanced features

VST plug-ins can do some high-tech things that AU plug-ins can’t. One example is sidechain inputs. This lets you use the audio from one track to control an effect on a different track, like making a synth pad quieter when a kick drum hits. Few AUs can do this, but lots of VSTs can.

VST also allows for multiple MIDI inputs and outputs. So, a single VST can control several different instruments at the same time. AU plug-ins are limited to just one MIDI input.

Some VSTs even let you use different audio interfaces or route audio between plug-ins in crazy ways. With AU, what you see is what you get.

Works on older systems

AU plug-ins only work on relatively recent versions of macOS. If you’re using an older Mac, some newer AUs might not work.

VST is more flexible with older operating systems. Even if you have an ancient Mac or PC, a VST plug-in will probably run on it. This lets you keep using your favorite plug-ins even if you can’t update your computer.

So which is better?

Okay, so AU and VST both have their strengths. But which one should you use?

Use AU if…

  • You only use a Mac and never need to collaborate with PC users
  • You use Logic Pro as your main DAW
  • You have an older Mac that struggles to run a lot of plug-ins
  • Do you like to keep your plug-in collection neatly organized
  • You mostly use standard instruments and effects without needing super-advanced features

Use VST if…

  • You use a Mac and PC or need to work with people on different computers.
  • You want access to the widest variety of plug-ins
  • You like to use cutting-edge, experimental plug-ins with unique features
  • You have an older computer and want maximum compatibility
  • You use a DAW other than Logic Pro

AU and VST are just two ways to access the sounds you want. There’s no clear winner. The best advice is to try both and see what works for you!

You can always have both AU and VST versions of your favorite plug-ins. Just pick whichever one works best in each situation. The most important thing is that the plug-ins help you make the music you want. Once you press play, no one can tell if you used AU or VST!

Munyaradzi Mafaro is a music enthusiast and he also likes to tackle topics of business, productivity, and the possibilities for growth in the digital world.