Ondes framboise - a DIY digital Ondes Martenot emulator

[clarionut]

Those of you who, like me, dream of owning an Ondes but could never justify it in reality may be interested in my Ondes Framboise project. It's a digital emulator of an Ondes based on a Raspberry Pi 3A+ running Pure Data plus some custom hardware and software, which attempts to provide all the features of a genuine Ondes Martenot:

Input by keyboard (including sideways motion for vibrato) or by ribbon, with a total range of 8 octaves (4 octaves plus shift of ±1 or 2 octaves)

Volume control by Touche button or foot pedal

All of the voices (Ondes, Creux, Gambe, Nasillard, Octaviant, petit Gambe & Souffle) + Tutti switch

Transposition buttons

Emulation of all four Diffuseurs (Principal, Résonance, Métallique & Palme) in software, each on its own output channel with built-in amplifiers

Pedal controlled low-pass filter

Legato / claquement mode

Although far from perfect it's a lot better than not having an Ondes at all! I'm in the process of publishing the design at the moment. 3D printed parts and construction details are on Thingiverse ( https://www.thingiverse.com/thing:4742145 ) and the code (Pure Data patch and custom server code) are on GitHub ( https://github.com/clarionut/ondes_framboise ). The current incarnation is a first prototype built solely to test function - it's far from elegant.

There are a couple of demos on YouTube - Rachmaninov 'Vocalise' ( https://www.youtube.com/watch?v=8Qs7qE2W0aA ) and Messaien 'Feuillets Inédits' ( https://www.youtube.com/watch?v=9ope-bVgxdk )

I hope you find it interesting!

[blue hell]

Cool project!

Nice demos too on the tube ... the rachmaninov piece is quite nice .. didn't know it.

Oh, and

Edit: and oh ..I've made the links in the post above clickable by adding some tactical spaces.

[wakyct]

Very interesting, also I had never heard of the Ondes before. What a fascinating instrument!

[BobTheDog]

Good stuff, joining in for progress updates...

[clarionut]

A very quick update: I've now posted block diagrams of all of the custom electronics in the constuction notes PDF document on Thingiverse. The audio chain basically just plugs together (with a bit of soldering if you want audio output sockets) so I haven't included that. I just hope someone out there is interested enough to have a go themselves!

My next step will be to replace the raspberry Pi 3A+ with a 3B+. The extra USB ports will allow
1. keyboard input from a MIDI keyboard. This will need some changes to the server code (it won't need to read the keyboard via the MCP23S07 and send note messages to Pure Data any more) and handling of legato/claquement mode in PD. These changes will be pretty trivial.
2. use of a USB stick to hold MIDI files for playback, and the 4-channel WAV files from recording mode. This will need some code to automatically mount the USB stick when it's inserted, and a menu item on the LCD to eject it.

@Blue Hell - thanks for the welcome and fixing the links! I've now worked out how to embed URLs

[clarionut]

I've added a circuit layout for the custom interface board to the construction notes on Thingiverse. I hope the details are right because I haven't built it yet! This version is intended to work with a MIDI keyboard rather than the switch-based keyboard of the prototype. I've just acquired a Korg microkey2-61 5-octave small-key keyboard and this looks very promising; the keybed is only a very little longer than the full size 4-octave keyboard of the first prototype. It's also easy to automount a USB stick (at least on Raspbian Buster), so pretty much everything is ready for prototype 2 running with a Raspberry Pi3B+. It will need some changes to both the Pure Data patch and the server code but these will be pretty trivial.

I just hope someone else will be tempted to have a go!

[BobTheDog]

I'm tempted

It's just the time!

I was thinking of trying to get it going on the Organelle: https://www.critterandguitari.com/organelle

[clarionut]

Interesting! I think it might be challenging to hook up the Ondes hardware to an Organelle, but I don't really know what's inside one.

My journey went in rather the opposite direction. The Ondes framboise started as an attempt to build an Arduino-based ribbon controller for an analogue synth. While I was struggling (and failing) with the analogue electronics side, I built an Organelle clone based on a Raspberry Pi to see if it could be done. That got me familiar enough with Pure Data and how to interface to the hardware that I realised I could build a complete Ondes rather than a 'simple' controller. I'd probably still be cursing op-amps if I'd stuck to the original plan!

[clarionut]

I've now uploaded a new version of the server code for the Ondes framboise on GitHub - ondes_server_M.c. This works with a MIDI keyboard rather than the switch-matrix keyboard of the original and handles the MIDI messaging and note priorities, so the Pure Data patch is unchanged from the original. On Raspbian Stretch the MIDI keyboard appears as /dev/snd/midiC1D0 - I've yet to find out if it's in the same place on Buster, so the code may need to be changed for this.

The construction notes (see here) on Thingiverse have now been updated with a more thoroughly tested version of the interface board layout. I hope this is now complete and correct (but no guarantees!).

[clarionut]

The new interface board and the server code to work with a MIDI keyboard have both been tested in the Ondes and everything works as expected. I used a Korg microKEY2-61 with everything running on a Raspberry Pi 3B for the extra USB ports - which also allow an externally-mounted USB memory stick to be used to transfer MIDI data in to and WAV files out of the Ondes.

New mounts to attach the keyboard to the linear rails and a new vibrato stop are still needed but these are pretty trivial and whatever I design will not work for anyone using different keyboard. The Thingiverse and GitHub pages are now fully up to date. I don't think there's much more I can add at this point, but I'm very happy to answer any questions if someone does want to have a go building an Ondes framboise for themselves.

[wakyct]

I was going to post this in Reddit's synthdiy but I saw you already did . Super cool work.