Free App, MiniDexed, Puts 8 DX7s On A $35 Raspberry Pi

Synthesist Floyd Steinberg shared this in-depth look at MiniDexed, an open-source synth DIY project that lets you run 8 instances of DEXED, a free Yamaha DX7 emulator, on a Raspberry Pi.

The Raspberry Pi is an inexpensive single-board computer platform, created to make computing affordable to almost anyone. The Raspberry Pi 4, like the one used for this project, is available for around $35 USD.

MiniDexed is a FM synthesizer, modeled on the Yamaha DX7, that runs on a bare metal Raspberry Pi (without a Linux kernel or operating system). On Pi Raspberry 2 and larger, it can run 8 tone generators, basically creating an open source equivalent of the TX816/TX802 (8 DX7 instances, without the keyboard, in one box).

Topics covered:

00:00 introduction
01:00 assembling the PI setup (LCD and rotary encoder)
01:32 other hardware needed
02:45 installing and configuring the software
03:30 navigating the menu, setting up a performance
06:34 important considerations
06:54 demo (synthwave… )
09:36 bye-bye

For more details, see the resources shared with Steinberg’s video and the MiniDexed site on Github.

17 thoughts on “Free App, MiniDexed, Puts 8 DX7s On A $35 Raspberry Pi

  1. Interesting that it runs as-is, without an OS.
    With PatchboxOS, a Raspberry Pi can run all sorts of things. Not sure what the record is for multitimbrality, in that context. It might be higher than 8. Plus you can run it headless.
    Hope there can be more diverse content on Raspberry Pi projects, here. Despite the fact that there have been shortages.

  2. Change the headline… The MSRP increased to $45 due to increased prices in components. However, Raspberry Pi 3 (not even the latest) is currently selling for 200 bucks… A Pi zero, which would would require you to run audio over mini HDMI costs 97 dollars!

    1. Raspberry Pi still costs the same in Europe. Who would ever pay $200 for a rPi 3??

      IMO this is a great project for those of us who already have unused Raspberry Pis around the house… I love them (and the DX7) and I wouldn’t buy one just for this. It’s never as easy build (nor as practical to use) as it looks.

    2. that is kind of crazy – when I got them on sale while back I bought like 4 raspberry pi 3+’s for around $20 a piece to use for emulators and such. guess I have a gold mine lol

  3. This thing, plus that site that makes random DX7 patches from AI, plus one of Uli’s MF-101 clones would be an awesome setup.

    Btw, pretty sure my Kurzweil can load up to 512 DX7’s. It fits an entire DX7 on one DSP block, there are 32 DSP blocks per patch, and it’s 16 patch multi-timbral.

  4. I’ve been following this project for a couple weeks now. It’s important to note it is a work in process, so it should continue to evolve for the better. A couple of issues I’ve run into:
    1. Couldn’t get it to run on anything less than a Pi4. Pi3 briefly before locking up. P1 and P2 not at all
    2. Couldn’t get DIN midi working very well. Not a show stopper for me, just would be nice to have
    3. There is no portamento. This goes back to Dexed itself. Would’ve been nice to have
    4. As mentioned in the video, the wiring documentation is not very good. I’m sure this will be updated when the team is polishing up things after development is completed.

  5. It’s worth pointing out that their claims that it replicates a TX802 are misleading. Unlike the TX816, which was essentially 8x DX7 Mk.I engines in a rack, the TX802 shared its engine with the DX7-IID/FD and that engine was somewhat different to the Mk.I in as much as it had some significant new features that greatly expanded upon it’s predecessor. Things such as fractional scaling, micro-tuning and poly unison mode were only found on the TX802 and DX7-IID/FD. DEXED is based on the Mk.I DX7 engine and therefore doesn’t have these features.

    If you load TX802 or DX7-IID/FD patches into DEXED, at worst they will produce garbage sound and at best they will sound similar to the intended patch but, in many cases, not identical.

    It is a common misconception that the TX802 was equivalent to the TX816 because it was 8 part multitimbral. What is often overlooked is that this multi-timbrality was achieved by using a single 16 voice Mk.II engine and therefore each part’s polyphony would be shared out of the 16 voices available. The TX816, with its individual TF7 modules delivered 8 part multi-timbrality, with each part benefitting from a full 16 voice polyphony.

    All that said, this is a clever implementation, even if DEXED is a little “off” in its accuracy. Plogue’s OPS7 is much more accurate in emulating the DX7 but DEXED is open source so is the obvious choice for something like this. It’s nice to see a little hardware unit with this kind of power, but the fact it has an even more limited interface than the originals is a shade ironic 😉

    1. thank you for saying what I came here to say. while related, this is not a proper replacement for a TX802. for me the biggest difference (besides the polyphony) is that a tx802 has 8 separate outs (in addition to a stereo pair) which makes it extremely flexible in a studio if you are wanting to mix/process those voices differently.

      I am hoping some kind of multi-out system is arranged for this, as having all 8 dexed voices on a stereo mix defeats a lot of the nuance for me.

    2. The TF1 is a 48KHz 16-bit device. It was the prototype for the II. Mk1 DX7 is 39KHz 12bit, with 4 volume control bits on the side.

  6. Very nice project!
    Kinda makes me longing for Yamaha to release an 8-part FM-Workstation in a QY-ish style form factor. A small, modern take on the old V50, basically.

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