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How to Setup System-Wide Equalizer on macOS Using BlackHole and AU Lab

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Many audio enthusiasts, music producers, and casual listeners who use macOS often notice a significant limitation: the operating system lacks a built-in, system-wide audio equalizer. While apps like Music (iTunes) have built-in EQs, they only affect playback within that specific app. If you stream music on Spotify, watch videos on YouTube, or play games, your audio profile remains flat and unadjusted.

For those who have invested in high-quality headphones, having a system-wide equalizer is crucial to unlocking their full potential. An EQ allows you to correct frequency response deficiencies, boost the bass, or tame harsh treble. Fortunately, you don’t need to spend a fortune on proprietary software. By combining two free tools—BlackHole (an open-source virtual audio loopback driver) and AU Lab (Apple’s free developer tool for audio mixing)—you can build a highly customizable, zero-latency, system-wide parametric or graphic equalizer.

In this guide, we will walk you through the complete setup process, from installation to advanced configuration and automation.

Understanding the Components: BlackHole and AU Lab

Before we dive into the installation steps, let’s understand how this setup works:

  • BlackHole: This is a virtual audio driver that allows applications to pass audio to other applications with zero latency. It acts as an audio bridge. Instead of routing your system audio directly to your headphones, you route it to BlackHole.
  • AU Lab: This is a digital audio workstation (DAW) and mixing application developed by Apple. It will capture the audio coming into BlackHole, apply macOS’s built-in system-wide audio effects (such as the 31-band graphic equalizer or parametric filters), and then route the processed audio to your physical speakers or headphones.

Step 1: Download and Install the Required Software

First, we need to download and install both software utilities on your macOS system.

1. Download and Install BlackHole

BlackHole is open-source and available on GitHub or via Homebrew:

  • Go to the Existential Audio BlackHole page.
  • Choose the 2ch (2-channel) version, which is perfect for standard stereo listening. The 16ch or 64ch versions are overkill for basic EQ setups.
  • Download the installer (.pkg) and run it. Follow the on-screen prompts to complete the installation.
  • Alternatively, if you use Homebrew, open Terminal and run: brew install blackhole-2ch.

2. Download and Install AU Lab

AU Lab is an official utility provided by Apple for developers:

  • Visit the Apple Developer downloads page (or search for “AU Lab download Apple Developer”).
  • You do not need a paid developer account to download it; a free Apple ID is sufficient.
  • Download the DMG file, open it, and drag AU Lab to your Applications folder.

Step 2: Configure a Multi-Output Device in Audio MIDI Setup

Because BlackHole is a virtual driver, sending audio directly to it means you won’t hear anything unless another app reads from BlackHole and plays it back to your speakers. To ensure you can monitor and control the audio pathway properly, we will create a Multi-Output Device.

  1. Open Audio MIDI Setup on your Mac (press Cmd + Space and search for “Audio MIDI Setup”).
  2. Click the + button in the bottom-left corner and select Create Multi-Output Device.
  3. In the right-hand panel, select the checkboxes for BlackHole 2ch and your physical output (e.g., External Headphones or MacBook Pro Speakers).
  4. Ensure that the Master Device drop-down is set to your physical output (e.g., Headphones) and that Drift Correction is enabled for BlackHole 2ch. This ensures the audio stays perfectly in sync without drifting.
  5. Rename this new device to “EQ Loopback” by double-clicking its name in the sidebar.

Step 3: Configure AU Lab for Real-Time EQ Routing

Now that our virtual routing is ready, we need to configure AU Lab to capture audio from the virtual bridge and output it to our physical device.

  1. Launch AU Lab from your Applications folder.
  2. Upon opening, it will prompt you to configure a document. Under the Audio Input Device dropdown, select BlackHole 2ch.
  3. Under the Audio Output Device dropdown, select your physical device (e.g., External Headphones).
  4. Click Create Document. A mixing board interface will open.
  5. On the input channel (labeled “Audio 1” or “Input 1”), locate the Effects section.
  6. Click the drop-down menu in the Effects slot, navigate to Apple, and choose AUGraphicEQ.
  7. The graphic equalizer interface will open. Here you can choose between a 10-band or a 31-band graphic equalizer configuration. Adjust the sliders to match your preferred sound profile (e.g., boosting sub-bass or reducing sibilant highs).
  8. Once satisfied, save your AU Lab configuration by going to File > Save As and saving the document as SystemEQ.aulab in a safe folder (like your Documents folder).

Step 4: Route macOS System Audio

With AU Lab running and processing audio, we must now tell macOS to send its audio to our virtual bridge.

  1. Click on the Apple Menu in the top-left corner of your screen and select System Settings.
  2. Navigate to the Sound section.
  3. Click on the Output tab.
  4. Select BlackHole 2ch. Once selected, play a song or video. You should see the level meters bouncing in AU Lab, and the processed audio should flow seamlessly to your headphones.
AU Lab and BlackHole EQ Setup on macOS

Step 5: Automate AU Lab to Launch on Startup

To prevent having to manually open AU Lab every time you restart your Mac, you can automate the process:

  1. Open System Settings and search for Login Items.
  2. Click the + icon under Open at Login.
  3. Navigate to the SystemEQ.aulab file you saved in Step 3.
  4. Right-click the file, select Get Info, and ensure it is set to open with AU Lab. By adding the preset file itself to your Login Items, macOS will launch AU Lab and load your exact EQ profile automatically.

Performance Comparison: BlackHole + AU Lab vs. Alternatives

While the BlackHole and AU Lab combination is incredibly powerful, modular, and free, it does require manual configuration. If you are comparing different equalizer options for macOS, it is worth looking at the landscape. You can explore more options in our comparison category.

Here is an overview of how the BlackHole and AU Lab solution stacks up against popular commercial alternatives:

Equalizer Solution Pricing EQ Bands System Latency CPU Usage Setup Difficulty
BlackHole + AU Lab Free (Open-source) Graphic (31-band) & Parametric Extremely Low (~4 ms) Very Low (<1%) High (Manual Routing)
eqMac (Basic) Free Graphic (10-band) Low (~12 ms) Low (~2-3%) Very Low (Plug & Play)
SoundSource Paid ($48) Parametric & Headphone EQ Low (~8 ms) Low (~2%) Very Low (Plug & Play)
Boom 3D Paid ($39.99) Graphic (31-band) Medium (~25 ms) Moderate (~4-5%) Very Low (Plug & Play)

The chart below illustrates the system latency (in milliseconds) added by each audio pipeline. Lower latency is critical for ensuring that audio remains in sync when watching videos or playing games on macOS.

macOS EQ Software Latency Comparison (Lower is Better) 0 ms 10 ms 20 ms 30 ms 40 ms BlackHole + AU Lab 4 ms SoundSource 8 ms eqMac (Basic) 12 ms Boom 3D 25 ms

Troubleshooting Common Issues

Setting up virtual audio routing can occasionally lead to minor configuration issues. Here are the most common problems and how to quickly solve them:

  • No Sound Output: Double-check that your Mac’s default system output is set to BlackHole 2ch, and that AU Lab’s input is set to BlackHole 2ch and its output is set to your physical headphones. Ensure the channel strips in AU Lab are not muted.
  • Audio Crackling or Pop Sounds: This is usually a buffer size or sample rate mismatch. Open Audio MIDI Setup and ensure that BlackHole 2ch, your physical output, and the Multi-Output device are all set to the exact same sample rate (e.g., 44.1 kHz or 48.0 kHz). In AU Lab, check the document properties and adjust the buffer size to 256 or 512 frames.
  • Volume Control Greyed Out: macOS disables native keyboard volume controls when outputting to virtual audio drivers. To resolve this, you can adjust the volume sliders directly in AU Lab, or adjust the volume control on your physical audio interface or headphones.

Conclusion

By leveraging the routing power of BlackHole and the processing capabilities of Apple’s AU Lab, you can construct a system-wide equalizer for macOS that rivals professional studio software. Whether you want to correct the response of a cheap pair of headphones or tune high-fidelity monitors, this solution gives you complete control over your soundscape.

If you are looking for more audio optimization guides or reviews of the latest audio gear, feel free to visit the homepage or browse our extensive blog category for helpful tips.

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