X0XB0X X0XI0 MODS, synth mod

x0xb0x x0xi0 mods

With the original TB-303 now well out of most producers’ price ranges, it’s time to look elsewhere if you want authentic acid sounds on a strict budget. Cyclone Analogic’s BassBot TT-303 is usually our recommended option, but its surface-mount circuit boards make it a tricky prospect for modding (that will change eventually – Robin Whittle reports that the TT-303’s circuit is so similar to the TB-303 that it will be possible to apply his Devil Fish mods to it).

Instead, if you want a moddable 303, you really have to look to the x0xb0x (pronounced ‘zocks-box’) clones. The x0xb0x concept is simple: recreate the original circuits of the 303 with components as close as possible to those used by Roland back in the early 80s. Originally developed as a DIY kit by Ladyada, the x0xb0x has since been built by thousands of DIYers and a number of companies who offer complete kits or ready-built units.

But building synths from scratch doesn’t really count as modding, per se, so why is it included here? That’s because a number of people have continued Ladyada’s work and developed mods for the basic x0xb0x setup, adding features and functions not included as standard. The most radical overhaul comes from Brian Castro, whose x0xi0 mods adding a list of new features as long as your arm, from overdrive and to 13 new CV, gate and audio inputs on the back panel.

A well-built x0xb0x can sound virtually identical to a real TB-303, but with the additional features of the x0xi0 mods, it can do a whole lot more.

16th June, 2015


  • What about the Mute Synth II?

  • Great read. Thanks.

  • The extensive envelope control on the x0xi0 is really the defining feature…but all in all, a wonderful, wonderful mod that transforms the x0xi0 into something else entirely…

  • Well, going back, the E! and and SuperMAX for the Yamaha DX7 are pretty amazing, but maybe not so much for your audience. The SCI Pro One TurboCPU+MIDI might be though.

  • What about Europa for Jupiter-6 and Gligli for Prophet-600? They’re great inexpensive massive upgrades. Gligli is even free.

  • There is no link for the Tubbutec mod in the article. Here is the link:


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