knob on

Your Rack. Within reach.

Use your iPhone or iPad as a touch surface for VCV Rack on your computer, with two-way parameter feedback.

What you need

iOS or iPadOS 17 or later, VCV Rack 2.6.6 or later, and Knob On Bridge 2.3.1. The published download is for Apple silicon Mac; Windows x64 source has passed basic testing with Rack Free 2.6.6. Put both devices on the same trusted local network. Audio runs in Rack on the computer.

Install the companion

The release download contains KnobOn-2.3.1-mac-arm64.vcvplugin and a ready-mapped test patch. Download Knob On Bridge 2.3.1.

  1. Quit Rack. In Finder, choose Go → Go to Folder and enter ~/Library/Application Support/Rack2/plugins-mac-arm64/. Copy the companion package into that folder, then reopen Rack.
  2. Add Knob On → Bridge to your patch. Its panel shows a short name such as knob-rb4m.
  3. Open Knob On on your iPhone or iPad. Tap disconnected, allow Local Network access, then choose the matching name under nearby Rack.
  4. Hold an unmapped dial or slider for about half a second. Its ring becomes dashed while it waits. Click the target knob or slider in Rack.
  5. Drag vertically to adjust. Changes made in Rack also update the app. Save the Rack patch to keep your mappings.

Windows

See the Windows source build and setup guide. Quit Rack, put the corrected Windows package into %LOCALAPPDATA%\Rack2\plugins-win-x64, then reopen Rack. In the phone app choose enter address manually and enter the IPv4 address shown on Bridge. Nearby discovery requires an existing compatible Bonjour runtime and remains an additional Windows test. Do not use the withdrawn first Windows test kit.

Make it yours

Tap a mapped control to change its color. Tap its label to edit the label and touch limits. Hold a mapped control again to disconnect it. Fine mode makes drags 10× slower; tap Fine again for normal sensitivity.

Linux

Linux x64 build and runtime tests passed under Ubuntu 22.04 emulation on an Apple-silicon Mac with Rack Free 2.6.6. Native Linux desktop and physical-phone checks remain outstanding. Linux uses manual IPv4 connection; nearby discovery is not implemented. See the Linux source build and validation guide. The published release remains the Mac preview.

If Rack does not appear

Check that both devices use the same local network and that Local Network access is enabled for Knob On in Settings. Allow Rack's incoming connections for your intended local network if your computer asks. Keep the firewall enabled. Guest networks may prevent devices from finding each other. You can enter the address shown on Bridge manually: a .local name on Mac or an IPv4 address on Windows or Linux. Use one Bridge and one controller at a time; the Bridge uses TCP port 8057.

What can be mapped?

Most standard bounded knobs and sliders from any Rack module. Stepped controls use Rack's snapping. The displayed value represents the parameter, so internal CV modulation may change the sound without changing that value.

Support

Email hi@zui.ooo. Include your app version, iOS version, Rack version, and a description of the issue. Do not send passwords or private patches.

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