Surge Synth Team OB-Xf is a continuation of the free and open-source OB-Xd synth project.
If you’re not familiar with the original open-source OB-Xd synth plugin by 2DaT, the name should give away the inspiration behind the project.
The inspiration, of course, was one of the most sought-after vintage synthesizers, the Oberheim OB-X (1979).
discoDSP took over the original 2DaT OB-Xd project a few years ago, and it spawned a €99 premium version.
It’s common for free synths to have a paid big brother, but attaching a paid version to an established freebie doesn’t always go down well with the audience, as we saw when Spitfire Audio added a paid subscription plan to the LABS collection.
Whether the premium version by discoDSP is value for money or not is a secondary issue in many ways. The bigger issue for most is that the free version received less attention and fewer updates.
The Surge Synth Team is breathing life back into this open-source project with OB-Xf, a fork of the original 2DaT project with no premium version in sight.
OB-Xf sounds fantastic already, but it’s very much a work in progress, and you should treat it as such (don’t use it on significant projects just yet).
The Surge Synth Team’s overhaul includes an interface refresh and many new features, with updates still coming regularly throughout development.
Some of the standout additions come from the filter section, with a new 4-pole mode and all Oberheim Xpander filters.
You have more modulation options with a second LFO (per voice); additionally, waveform buttons have been replaced by knobs, allowing you to morph from sine to triangle, pulse to saw, etc. Sticking with modulation, the filter envelope section now features an inverted mode.
OB-Xf also features a newly implemented ring modulator in the mixer section, along with multimode noise color (white, red, and pink).
You’ll also see a new programmer section at the bottom of the GUI.
Keep in mind that patches from the original OB-Xd are not compatible.
OB-Xf is available in AU, VST3, LV2, CLAP, and Standalone formats for macOS, Windows, and Linux. More info on the OB-Xf GitHub page.
Anything with the Surge Synth Team’s backing is promising, so keep an eye on the project’s regular updates; this is an exciting one.
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Download: OB-Xf (FREE)
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Last Updated on September 23, 2025 by Tomislav Zlatic.
