OB-Xd for MPC OS (unofficial port)

A native ARM VST2 build of the OB-Xd synthesizer for first-generation Akai MPC / Force standalone units (developed and tested on an MPC Live II, MPC OS 3.x). Built with sd88me/mpc-vst-plugins (MIT).

Unofficial: not affiliated with or endorsed by discoDSP, 2Dat, Akai or the community OB-Xd project. See CREDITS.md.

What you get

• All 77 OB-Xd parameters, 8 voices, on a full-screen touch panel in the community theme's style, split over three pages with big knobs and buttons for fingers (tabs at the top): OSC (master, global, oscillators, mixer, control, amp envelope), FILTER (filter, filter envelope, modulation, voice variation) and SETTINGS for the controls the panel has no place for. BANK, PATCH and BPM are on the OSC and FILTER pages.
• THEME (a drop-down in the top left of the SETTINGS page, touch only): four looks, switched live. Slate (default), MPC Grey (classic MPC grey with green LCD displays), MPC Black (MPC1000-style black with amber displays) and Retro (cream with orange LED displays). The BANK / PATCH / BPM displays, legato and voices readouts change colour with it. Saved as a normal parameter at the end of the list, so older projects load unchanged.
• FREQUENCY (Hz): reference pitch, 400 to 480 Hz (default 440), on the SETTINGS page. It sits on top of TUNE and is not stored in presets.
• STOP: a panic button (all notes and sound off) next to VAM. LEARN, CLEAR and MENU are removed (no MIDI learn on the MPC).
• BANK / PATCH selector at the top centre of the OSC and FILTER pages, each with a left and a right arrow (right = next, left = previous, they wrap around). Banks are plain OB-Xd .fxb files in the banks folder next to the plugin; the release ships the Moby Pixel bank and three banks of CC0 (public domain) patches. Your own banks go in a my-banks folder next to banks; banks itself is replaced on every install, so it only ever holds what the release ships. Names longer than 16 characters end in .. so they stay inside the display. The MPC PRESET menu lists the patches of the current bank.
• Tempo sync for arps and sequences: OB-Xd has no arpeggiator or sequencer of its own; those patches use the LFO. Turn on SYNC (under MODULATION on the FILTER page, also on the SETTINGS page) and the LFO follows the MPC tempo, which the BPM display in the top right corner shows: the LFO RATE knob then picks how many cycles per beat (1/8, 1/4, 1/3, 1/2, 1, 3/2, 2, 3 or 4), and it restarts when you press play. Loading a patch sets LFO SYNC to what the patch stores, which for the stock banks is off.
• BROWSE page: every bank in a list on the left, the patches of the bank you are looking at in a grid on the right (24 to a page, with page arrows). Tap a bank to look at it (nothing changes in the sound), tap a patch to play it. The two displays on top show what is playing. The first Q-Link scrolls the banks (looking only, it never loads a patch). The second scrolls the patches of the bank you are looking at and plays each one; it stops at the first and last patch and never moves into another bank (pick the bank with the first knob or by tapping it).
• Loader (on the BROWSE page): the drop-down at the bottom left switches the two lists into a file browser. BANK (.FXB) shows places (plugin folder, internal, USB / SD, all files) on the left and folders plus .fxb bank files on the right; PRESET (.FXP) does the same for single .fxp programs. Tap a folder to open it (^ UP goes back), tap a file to add it: it is copied into my-banks (programs into my-banks/presets, which appear together as the bank My Presets), so it stays installed across restarts and updates and never has to be loaded from a folder again. A bank shows up in the bank list, a preset plays straight away. Choose PATCHES to go back.
• Q-Links only where they are practical on the knobs, one page per tab (no sub-pages), one panel section per column of four knobs. OSC: MASTER, OSCILLATORS, MIXER, AMPLIFIER ENVELOPE. FILTER: FILTER, FILTER ENVELOPE, MODULATION. BROWSE: banks and patches. SETTINGS: its knobs, then its buttons. The column you are on is outlined on the screen. Everything else is on the touchscreen.

Engine: OB-Xd 2.10 source (the DSP of the community GPL fork). discoDSP's later releases (2.11 to 2.20) are binary-only, so their changes are not in here.

Install

Use a release zip: unpack it and follow INSTALL.md inside (run install.sh on the device as root, or copy the portable/ folder into a Synths folder on the internal drive). Back up MPC.settings first. External drives are mounted noexec, so install to the internal drive.

Build it yourself

Ubuntu or WSL2 (Docker with QEMU for arm32v7; run it in the Linux home folder, not on a Windows drive):

git clone https://github.com/sd88me/mpc-vst-plugins ../mpc-vst-plugins
git clone <this repo> mpc-vst-obxd && cd mpc-vst-obxd
./build.sh                    # writes vst/build/ (obxd.so, skin/, pluginlist-entry.xml)
../mpc-vst-plugins/tools/test_port.sh vst/vst.json     # offline x86 test, must print PASSED

The skin is already generated and committed, so there is nothing else to run. Packaging and catalog listing: docs/RELEASING.md.

Regenerating the skin (optional)

python3 tools/make_skin.py skin-source/"Default Skin"             # Pillow needed: sudo apt install python3-pil

You can point it at a theme from your own OB-Xd install. That is for your own device: those files are not ours to redistribute, so keep the output out of public releases.

More banks (optional, for your own device)

The release ships the Moby Pixel bank (GPL) and three banks of CC0 patches converted from OB-Xf's factory set (79 patches, credits in banks/CREDITS-CC0.md). OB-Xd's own factory banks belong to discoDSP and their authors, so they are not included. If you have OB-Xd installed (it is free from discoDSP), copy its .fxb files into a my-banks folder next to the plugin's banks folder on the MPC (create it; the plugin reads both):

/sdcard/Synths/sd88me - VST - OB-Xd/my-banks/

Re-open the plugin and they show up in BANK, in file-name order. Patches still called "Default" or "Init" are hidden. The installer keeps that folder when you upgrade. Do not publish those files or a zip that contains them (tools/make_releases.sh can build such a zip for your own device, in dist-private/).

Licence

Code: GPL v3 (see LICENSE). Anyone you give a built plugin to is entitled to this source, so link to this repository wherever you share binaries. The skin artwork (skin-source/, vst/images/) is gitterdude's community theme under CC BY-SA 3.0, see skin-source/NOTICE.md. The Moby bank (banks/) is from the GPL community repository, see banks/NOTICE.md; the CC0 banks are credited in banks/CREDITS-CC0.md. Everything else, with who wrote it: CREDITS.md.