We’re used to seeing the Raspberry Pi crop up in a wide range of the projects we show you here, but it’s fair to say that they usually feature some sort of operating system. There’s another way to use a Pi, more akin to using a microcontroller such as the Arduino: by programming it directly, so-called bare-metal programming. MiniDexed is an example, and it copies a classic Yamaha professional synthesiser of the 1980s, by emulating the equivalent of eight of the company’s famous DX7 synthesisers in one unit. It takes almost any Pi, and with the addition of an audio board, a rotary encoder, and an LCD display, makes a ready-to-go unit. Below the break is a video of it in operation.
It’s fair to say that we’re not experts in Raspberry Pi bare metal programming, but it’s worth a diversion into the world of 1980s synthesisers to explore the DX7. This instrument was a staple of popular music throughout the 1980s and was a major commercial success for Yamaha as an affordable FM synthesiser. This was a process patented at Stanford University in the 1970s and subsequently licensed by the company, unlike other synths of the day it generated sound entirely digitally. It’s difficult to overestimate the influence of the DX7 as its sound can be heard everywhere, and it’s not impossible that you own a Yamaha FM synth even today if you have in your possession a sound card.
Curious about the DX7? Master chip-reverse-engineer [Ken Shirriff] exposed its secrets late last year.
nice! A lot of expensive equipment replaced with a tiny little box. I checked on ebay, these things are going for $2000+, it’s insane what people want for old technology.
The tx-802 is still quite cheap and packs 8 2voice dx-7’s in one box. Multi timbral, and works very smooth with dexed. Only be aware of leaky capacitors.
The new Volca FM 2 comes out next month for under $200. No need for a $2,000+ DX7. This project looks cool, but it’s not very tweakable.
not very tweakable? It’s open source, you can literally tweak every bit of it ;)
I mean in real time with knobs as you play it. A synth isn’t a static voice any more- it’s all about the modulation.
Yes it is: you just have to do it all with the single encoder.
If instead what you want is to be able to use dedicated controls per function/operator then that is on its way too: https://github.com/probonopd/MiniDexed/issues/63
FM synths in general are infamous for not being tweakable. This has one encoder, and if I’m not much mistaken, I believe the FM7 does as well. But unlike the FM7, this can be rewritten to change that.
Oh the beloved QY-70 <3
This looks is a great project to try! I’d love to try the Raspberry Pi MT-32 setup sometime too.
Wow, this sounds nice! At least half of that is his playing though! I’m tempted to build one but I know I’d not be able to use it as well!
Also see https://github.com/dwhinham/mt32-pi for a similar project (Roland instead of Yamaha).
Been enjoying playing around with this. Happened to have a pi4 sitting around from a stalled project.
Just need to mount it in/on a dedicated controller. Just waiting on midi parameter editing to be implemented. Great project and it will have a place in my setup.
This is great, and I’d love to see more raspberry pi projects that use bare metal code or custom kernels instead of the standard raspian
Could this be done with a Raspberry Pi Pico (given that most of the other Pi versions are expensive and/or unobtainium lately…)?
Guessing not. It’s still kinda computational-horsepowery. But surely you could stand up a DX7 equivalent in a Pico.
https://github.com/probonopd/MiniDexed#system-requirements
Someone has ported the original Dexed to the Pico (see: https://www.sayatone.com/fmsynthesis/raspberry-pi-pico-dx7-clone/) and there is also microDexed for the Teensy (see: https://www.parasitstudio.de/)
I’ve not used either, but I’ve played with the circle-based MT32-Pi and other “bare metal” synth projects (see my own blog).
MiniDexed will apparently support the original RPi too, but only with a single tone generator rather than 8, but I’ve only used it so far on a Pi 4 myself.
Kevin
If you do not have a PI but have a Teensy 4.1, you can look into MicroDexed, which is the base where MiniDexed started upon. We are also working very hard on this to put in as much as possible, but a slightly different approch as the MiniDexed fellows.
https://codeberg.org/positionhigh/MicroDexed-touch
https://www.youtube.com/watch?v=G6lSqf8H_4g&list=PLHTypoMU1QoGOXPli8bjR6MknPiQpubHl