MicroDexed - DX7 to go


FM8 is MicroDexed^8!

MicroDexed is nearly full compatible with the “old” DX-7 (MicroDexed has no portamento, but 3 slightly different sound engines and less noise).

The DX7-II has a better engine and also less noise against the “old” one. You can also split or double voices (then only 8 notes per voice instead of 16), it has micro-tuning and some other smaller goodies.

Both DX-7 have 6 sinoid operators.

FM-8 has 8(!!!) sinoid operators, much more algorithms and features (AFAIK an Arpegiattor and effects). It is a FM-Monster and IMHO sounds really cool. But it is software… :neutral_face:

Forgot to answer your question:
Yes - (IMHO) FM8 can import DX7-SYSEX data. But with MicroDexed you currently cannot edit sounds (only with external SYSEX editor like CTRLR - but this is currently untested).

The other way (FM8->MicroDexed) may be possible but only if FM8 can export DX7-SYSEX format and only without the additional gimmicks of FM8.

Regards, Holger


FM8 to MicroDexed would be my interest so I could use FM8 as a sound editor and MicroDexed as a player.I would be pleasantly surprised if it can do that. I saw a project that put a breath controller and joystick on the CPU used in this project. Maybe I could integrate it, but maybe it would require too much from the CPU; we will see. I made this project to experiment with sound and figured to integrate the hardware pieces into one box and just run different software, but maybe it would make sense to add breath and joystick to the MicroDexed.

Regards, Len


Maybe this could work. You must have in mind that you only can use algorithms and parameters that a DX-7 supports. And FM8 must store the sounds as a 32-Voice-SYSEX (DX-7 compatible).

If you have an external (breath) controller which sends MIDI data with the expected controller number, it should work.

Regards, Holger


@LenR Perhaps JSynthLib is also a solution for editing? I hope this one will work, so I can check if my SYSEX implementation is ok.

Regards, Holger



I got my JSynthLib running and must say, that this is the first MIDI editor which is working for me on top of Linux. I now have FINALLY a patch editor for the MicroDexed and could therefore test the SYSEX handling (and repair it!). I don’t know if I got all the bugs fixed in the meantime, but at least the basic programming works.

What Dexed still lacks is receiving and storing complete VOICE- and BANK-SYSEX data. There is still no possibility to save parameters anyway. That comes next.

Regards, Holger

BTW: Dexed does now software MIDI-THRU. It forwards all data from the three possible ports to the other. Currently it is enabled by default and it is only a compile-time-option. This will be a configuration option later.

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The next PCBs are in production :slight_smile: I think next kits will be available end of May 2019.

Regards, Holger


Have you added the optional life vest with additional buoyancy aid systems and GPS marine radio transmitter to the one coming here?
And, please, do not send it using air mail, or else it will be carried by a 737 Max 8 for sure with pilots taking a slight deviation to the Bermuda triangle… like its unfortunate sibling… :crazy_face:


Some more MicroDexed PCBs just arrived…


Hello @C0d3man,

I am very interested in this project, but maybe more to play MicroMDAEPiano with this.
Do I have to drill holes in the PCB myself? Where would I find a BOM or would you include all parts with the PCB?

Greetings and God bless, Marius


It’s already a nest of them…!

Now THAT Would be some machine. . . ! the New TX16Z or whatever Yamaha called their 8 DX7’s in a box. . .

THE TX 140Z or similar !!


MicroMDAEPiano is working, but not ready. The following is currently missing

  • a LCD UI
  • storing/loading of parameters
  • some more FX (like chorus, delay, reverb, limiter, …)

Everything (except the modulated chorus and the limiter) is probably not a problem to code, but I currently havn’t enough time for this… :neutral_face:

No. PCB is ready for assembling.

I have to revise the BOM for Revision 1.8 and will sell the PCB or a (nearly) complete kit (without Teensy and Audio board). Revision 1.7 BOM and Build-Manual is located at codeberg.

But for now I must try the complete board hopefully not made something wrong before (and everything is for the recycling yard…)

Regards, Holger


A Dexed-cluster… but I think 16 (or more of them) would need a bigger case than the original TX81…

Regards, Holger


Seems to work, but not all features are currently tested (have to check MIDI OUT, THRU and audio in… also have to wire both encoders)


… and everything is checked: board works! :star_struck:

MIDI-IN: check
MIDI-OUT: check
MIDI-THRU: check
AUDIO-IN: check
AUDIO-OUT: check

Next steps: packing kits. Some parts are out of stock… and I will buy some T_3.6 and matching audio-boards for pre-programing the T_3.6.

Build time (for me) is about 1.5h - 2h.

Regards, Holger


Congrats! New tablecloth, though! I was rather fond of the red polka-dots :grin:


Sorry, didn’t found the other one. Will do this hopefully for the next photos.

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I definitely want a kit. Or two.


Hello folks,

I like these synthesizers that are housed in the microcontrollers. It’s pretty amazing what those stuff can do nowadays.

Earlier this year, I have attempted to port the MicroDexed to ESP32. However, I ran into a major roadblock - it only works up to 8 voices. More than that, the whole thing will stutter.

I have written a simple app that plays a song in Miditones format using the MicroDexed: https://github.com/uncle-yong/esp32-microdexed/

Suggestions are welcome to improve the code. And yes, it’s still in progress and it’s not final.


Hi @The_YongGrand

thanks for sharing! This looks very trendsetting for the next stage of shrinking the DX7/Dexed :slight_smile:

What kind of ESP32 do you use? Do I need a special one or do all the ESP32 have an I2S interface?
Where to get a PCM5102 board and how do I have to connect it to the ESP32?

That’s really strange because a Teensy has only 180MHz and can calculate 16 (or more) voices (plus reverb, delay and EQ) - depending on the used algorithm.

Regards, Holger


Hello Holger W.,

I used a basic ESP32 dual-core you can get from the online stores. In my test, I used an Gravitech ESP32. All of the ESP32 I’ve seen so far has i2s interfaces.

The PCM5102 board I got is from many online stores too. Here’s a picture of this: https://m.aliexpress.com/item/32826879559.html?trace=wwwdetail2mobilesitedetail&productId=32826879559&productSubject=Interface-I2S-PCM5102-DAC-Decoder-GY-PCM5102-I2S-Player-Module-For-Raspberry-Pi-pHAT-Format-Board

I have listed the i2s connections in the code - I’ll type it in for you here once I’m on the desk.

Unfortunately I have the same question as yours as I tested it. I suspect that it could be slower running the code from the external flash. I hope someone can optimize that code and have it run as what as it is intended.