Tool for unpacking, modifying and repacking firmware for the OP-1 synth by Teenage Engineering.
Branch: master
Clone or download
richrd Update
Added link to original custom FW thread and improved wording.
Latest commit 3cb3f0c Aug 27, 2018
Type Name Latest commit message Commit time
Failed to load latest commit information.
images Updated readme and removed unneeded tape background. Jan 19, 2018
op1repacker Release 0.1.4 Jan 19, 2018
.gitignore Initial commit Jul 2, 2016 Added files that I accidentally missed. Dec 27, 2017 Added install instructions. Jan 25, 2018
LICENSE Initial commit Jul 2, 2016 Update Aug 27, 2018 Added SVG patch mods. Jan 17, 2018 Fix release script. Jan 4, 2018 Added SVG patch mods. Jan 17, 2018

OP-1 Firmware Repacker

The tool for unpacking and repacking OP-1 synthesizer firmware. It's based on the collective research we've done at the custom firmware thread. This allows you to access and modify the files within the firmware as well as repacking the files into a valid installable firmware file. The tool also includes some modifications that can be automatically applied to the firmware. See Modify below for more information.

  • Requires Python3
  • Tested on Linux, OS X and Windows 10

Filter Effect Custom Iter Graphic Tape Invert CWO Moose


Don't use this unless you know exactly what you are doing! I take no responsibility whatsoever for any damage that might result from using this software. You will void your OP-1 warranty and in the worst case brick it using custom firmware. Everything you do with this is at your own risk!


To install op1repacker run the following command:

sudo pip3 install op1repacker


Unpack & Repack

op1repacker unpack [filename]   # Unpack an OP-1 firmware file.
op1repacker repack [directory]  # Repack a directory containing unpacked firmware.

The firmware is unpacked to a new folder in the same location as the firmware file is. If you unpack the firmware file op1_218.op1 at /home/user/op1/ you'll get a folder /home/user/op1/op1_218/ containing the unpacked files. The same logic works for repacking, the new firmware file is saved in the same location, but the name will be op1_218-repacked.op1.


The firmware can be automatically modified with some predefined mods. These have been tested on the firmware version 225. Currently available mods are:

  • iter

    Enable the hidden iter synth

  • filter

    Enable the hidden filter effect

  • subtle-fx

    Lower the default intensity of effects. This allows you to turn effects on without affecting the sound too much. You can then turn them up as you like. This helps with live performances and avoids a sudden change to the sound when an effect is enabled.

  • gfx-iter-lab

    Add custom lab themed visuals to the iter synth.

  • gfx-tape-invert

    Move the tracks to the top in the tape screen to make them easier to see.

  • gfx-cwo-moose

    Swap the cow in the CWO effect with a moose.

To enable a mod, first unpack the firmware, then run the following command (replace mod_name with the mod you want and [directory] with the location of the unpacked firmware) and repack the firmware after that.

op1repacker modify [directory] --options mod_name

For example, to enable all mods run this command:

op1repacker modify [directory] --options iter filter subtle-fx gfx-iter-lab gfx-tape-invert gfx-cwo-moose

More modifications might be added later.


If you want to participate please submit issues and pull requests to GitHub. Pull requests should be opened against the dev branch. I like to only push tested new versions to master. You can also let me know of possible mods you would like to see by openning a new issue and describing the mod. Keep in mind that new features can't be added - only changes to what's already in the firmware are possible.