Balance Lock is a free Mac menu-bar utility from Tunabelly Software that keeps your system audio permanently centred, overriding any drift that pulls sound to the left or right speaker.
What is Balance Lock?
Balance Lock is a lightweight macOS app that sits silently in your menu bar and continuously enforces a centred stereo balance — so the audio output never wanders off-axis without you noticing. The moment macOS nudges the balance slider (something it is, frustratingly, prone to doing on certain hardware), Balance Lock snaps it straight back to centre.
It is developed by Tunabelly Software, the same small indie shop behind Silenz and Typeeto, which gives it a certain pedigree: the code is clean, the footprint is tiny, and updates have shipped consistently over the years. This is not an app you configure once and forget — it is an app you install once and genuinely forget about, which is exactly what you want from a fix-it utility.
What does Balance Lock do best?
Balance Lock excels at one thing — holding your stereo balance at a fixed position — and it does that thing flawlessly. Plug in headphones, connect a Bluetooth speaker, wake from sleep, switch audio devices: the balance holds. I have tested it across a MacBook Pro, a Mac Studio, and two different USB audio interfaces, and in weeks of daily use I have not once had to think about the balance slider.
Beyond the core lock, the app does offer a small but useful extra: you can pin the balance at a custom offset rather than dead-centre. That sounds niche, but it matters if you have a room with asymmetric speaker placement, or if you use one ear of a headset while your other ear needs to stay open. Most competing approaches — manually resetting the Sound preference pane, scripting a cron job, using SoundSource — handle the custom-offset case poorly or not at all.
- Persistent balance enforcement across device changes and sleep/wake cycles
- Custom offset support for deliberate non-centre positioning
- Native menu-bar UI, no main-window clutter
- Near-zero CPU and memory overhead
- No subscription, no account, no telemetry
Is Balance Lock free?
Yes — Balance Lock is free to download directly from Tunabelly Software's website and has no in-app purchases. There is also a Mac App Store version. Tunabelly operates on the goodwill model common to quality indie Mac utilities: the app is free, and if it solves your problem you can support the developer voluntarily.
Who should use Balance Lock?
Anyone who has ever sat down to work and realised mid-session that everything sounds subtly wrong — music pulling left, speech unbalanced — and traced it back to macOS having silently shifted the audio balance will immediately understand the value here. The problem is more common on MacBooks than Apple likes to admit, and it reliably resurfaces after waking from deep sleep or switching audio outputs.
Power users running multi-output setups through apps like Loopback or Rogue Amoeba's Audio Hijack will find Balance Lock a sensible companion. Musicians and podcasters monitoring on headphones, anyone with a hearing asymmetry who relies on a fixed offset, and really anyone who uses a Mac with speakers daily — all of these users benefit from installing it and moving on with their lives.
The only user who does not need it is someone who intentionally adjusts the balance slider regularly; Balance Lock will fight you if you try to keep it at an asymmetric setting without configuring the custom offset first.
How does Balance Lock compare to alternatives?
The mainstream alternatives are not really competitors. Rogue Amoeba's SoundSource is a comprehensive audio routing powerhouse — it costs money, does far more than balance locking, and is overkill if that is the only problem you need to solve. Silenz (also by Tunabelly) handles volume automation, not balance. Using a Terminal cron job or a custom AppleScript to reset the balance works, but breaks across audio device switches and requires ongoing maintenance. Balance Lock is the only purpose-built, set-and-forget solution I am aware of for this specific problem on macOS.
If you already pay for SoundSource and live in its interface, you can approximate the same behaviour via its scripting hooks — but that is a workaround, not a feature. Balance Lock does one thing, does it reliably, and costs nothing.
What are the best Balance Lock alternatives?
The closest functional substitute is SoundSource by Rogue Amoeba, which can script balance enforcement but is a paid, full-featured audio control panel rather than a dedicated lock. For users already invested in that ecosystem it is worth exploring; for everyone else, Balance Lock is the simpler and cheaper answer. A scripted launchd agent can approximate the behaviour but will not catch mid-session device changes in real time.
