MicroDexed - DX7 to go


Many thanks! In fact it has started because I don’t want to carry this heavy DX7II in a heavy flight-case anymore :slight_smile:.

Regards, Holger


2ms is nothing… no ??
I wonder how is the latency between : the pianist touches the key, the key starts to move, the hammer starts to move, the hammer hits the string… in fortissimo, but also in pianissimo…
On my Studiologic SL88 (Fatar keyboard), pressing a keysometimes seems like ages… Especially during pianissimi…

I think I bought mine directly from Xavier… But he often is in holiday in summer…
What is good with the PreenFm is that it has several LFOs… Something I would love to see on Dexed… and other extra features, like the modulation matrix…
What is bad it that there is much aliasing noise… and the more polyphony, the weaker is the sound… but not the alisaing… Added to the fact that a 6op preset can only have 9notes polyphony…

Yes… But at the time when Yamaha released the DX7, there were no DT7, or whatever…
The interface was just one knob, and many submenus… That was unusual at a time when each control had its own knob visible on the front panel…
Plus… It was at a moment when many pianists who had never touched a single synthesizer, and would even criticize them, would turn to synths because that was the fashion of the moment… So of course, they were rapidly lost… Organists were less lost, but still…
And whatever they would read about FM synthesis was in the mathematical mode… It was so much more obvious to play with a filter cutoff knob and have an immediate result… That’s why the Korg MS20 (a big shit, to my taste) was so popular…


My opinion is that it’s not the only bonus : Yamaha DX7 (at least the first generation) had a poor D/A converter, and there was a rather loud background (white) noise… I don’t have this feeling with Dexed…
And maybe Dexed has less aliasing ?? Like it would have a better bit-resolution ??


Hi Holger!

Congratulations for your PCB design … :medal_military::medal_military::medal_military:
When you have debugged and it’s working , i would like to have the honor of trying to follow your steps and build my own “Full MicroDexed”, so please, reserve a PCB for me :wink:

Meanwhile, of course, i already have ordered the teensy and the audio interface … :sunglasses:

The best!


I will want one too… but maybe you’ll sell complete kits ??


Sadly here in Brazil, the teensy is so expensive :frowning: please reserve a PCB for me too… Without it, I will have no utilities for teensy board and audio board if I buy them


I really hope that my first badge will not have much problems (it’s my first KICAD5 project and the first time I am NOT using a stripe board :sweat_smile:).

The first (working) badge of PCBs is reserved for Zynthianiacs! Perhaps I will create kits later.

Regards, Holger


BTW: KICAD5 sources (schematics, netlists, gerber files) are located here:

Regards, Holger


…and who those “Zynthianiacs” are? :smiley:



Yes @Axeman, you too! :wink:


Less aliasing? Yes, maybe. Dexed itself has three engines:

  • Modern : this is the original 24-bit music-synthesizer-for-android implementation.
  • Mark I : Based on the OPL Series but at a higher resolution (LUT are 10-bits). The target of this engine is to be closest to the real DX7.
  • OPL Series : this is an experimental implementation of the reversed engineered OPL family chips. 8-bit. Keep in mind that the envelopes stills needs tuning.

So the Modern engine may have the best quality - but perhaps it makes a difference to the original DX7 sounding. When I have much more time, I will try to setup a direct comparison betwenn my DX7II and MicroDexed (both get the same MID data and one is located to the left, the opther to the right audio channel).

My default is curerntly the Modern engine, because I like the sound quality.

Regards, Holger


Keep in mind that this will not be a “fair” comparison. The DX7II DAC has a few bits (2 or 4, don’t remember at the moment) more than the original DX7 one and a sligthly different MIDI implementation…


Yes. But it is the “easiest” way for me to get something like that. I will borrow a DX7 from a friend later, so a fair comparision is also on my plan.

Regards, Holger


Well, I can steal…ahem…borrow the @TheBorga 's orignal DX7 to do some tests.

For science!! :smiley:


Breadboard DX7 with a PT8211 instead the Teensy Audio Board.

… has only audio output and is really tiny…


The PCBs are in Germany - yeah. But now the journey with german customs starts…


But surely we are one big happy European family …?

Aah sorry I’ll get back to you.


Na, Brexit means Brexit :slight_smile:


Has anyone of the hardware-cracks in this forum a hint for a good (cheap?) front panel producer?

TIA, Holger


Do you like the official Zynthian Case? Perhaps Ramón could help you … :wink: