[queued] MiniTouch 2nd edition, T4.0 compact synth


Well-known member

Here is the 2nd edition of the MiniTouch, a compact and affordable stand alone synthesiser. I focused on musicality, portability, and fun. Here are the main features :
- capacitive 18 notes builtin keyboard
- builtin small speaker, battery
- line + headphones output
- 16 pots (32 settings with the "shift" button)
- 10 scales : European, African, Asian, Eastern Europe, Middle East... scales
- 2 oscillators, noise generator
- 2 filters
- 4 ADSR envelopes (amplitude, filter, FM, pitch)
- 20 presets
- external app for easier sound presets creation
- 35 $

I don't share the code at the moment because I think it makes no sense : every piece of code is linked to the hardware and optimised for a dedicated layout. But I would be very happy to give some examples and chunks of code to illustrate how it works. So feel free to ask !

Here is a short video :

I have designed a control panel to edit the presets. Although all the controls are available on the MIniTouch I though it would be more convenient to have a nice interface. I has been done with the open source software Ctrlr :

Here are a few pictures of the MiniTouch and PCB :


and the control panel :

Enjoy !
Can you give me a quick rundown on what's changed since the previous version covered in an article on January 10, 2024? Hardware looks to be quite well updated, Teensy 4.0 rather than Teensy 3.2 and more pots... but a quick explanation of the practical benefit the better hardware brings for people actually using this synth would really help for publishing a 2nd blog article.

But I would be very happy to give some examples and chunks of code to illustrate how it works. So feel free to ask !

Yes, please share if you can?

Especially when we post about the article on social media, people show usually more interest if we can say the source code is available.
Hi Paul,

Actually the T4.0 version has a lot of improvements, even if it looks pretty similar. Here are the main ones :
- 2 oscillators (vs 1)
- 8 voices polyphony (vs 4)
- FM modulation, AM "ring" modulation (new)
- noise generator with ladder filter (new)
- LP, HP, BP filters (vs LP only)
- 1 filter per voice, with note tracking for the cutoff frequency (vs only 1 global filter for all voices)
- 4 ADSR envelopes : amplitude, filter, FM, pitch
- nice reverb thanks to Piotr Zapart, www.hexefx.com
- delay (new)
- 20 editable presets saved with builtin EEPROM (new)
- new drum kit with 44,1kHz samples
- usb midi host (new)
- more pots and switches
- larger keyboard (20 keys)
- 4 digits old style 7-segments display
- new class D amp (PAM8306) with bigger loudspeaker
- new PCB design to get rid off residual noise
- new laptop midi interface for sound design

I don't publish the source code because I think it makes no sense. First, it is big and very difficult to read. It is also thightly linked to the hardware, and won't work with other designs. When I was learning, complete codes didn't help me. Little pieces of code, explained and documented, were so much more helpful. That's the reason why I prefer not sharing the complete code. And people ask me very often about some specific points to develop their own projects. For instance, many students contact me for art installations, musicians, local fablabs, enthusiasts... And I try to answer to all of them, with short examples. Some people even came to my place and we work together, which is so great ! By the way if you plan to come to France, you are more than welcome (seriously) !
That being said, I can publish my code if you think it is a real plus.

Have a good day/night,
Clermont-Ferrand, France