ArcSyn-0 - polysynth built with a Raspberry Pi Zero

...and how to do so...
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kryptonaut
KVRian
751 posts since 25 Apr, 2011

Post Sat Jan 04, 2020 9:41 am

After making my bat detector I decided to try something more ambitious for my next Raspberry Pi project - so I designed and built a 6-voice polyphonic synth, the ArcSyn-0.

Image

There are dual oscillators plus sub-osc per voice (combine oscillators using mix, hard sync or ring mod), dual loopable envelopes per voice, LP/HP 24dB filter per voice, LFO, arpeggiator, mono/poly/unison mode, stereo delay, phaser, stereo chorus, distortion, oscilloscope waveform display, save/load presets in non-volatile memory. Built-in keyboard, joystick, speakers, serial MIDI input.

It was great fun to design and build, and sounds nice too - IMHO :)

More info on the project here: http://jaggedplanet.com/synthesiser.asp

First couple of recordings:
Sequence1.mp3 - A Berlin-school-inspired piece based around an arpeggiated sequence, consisting of seven tracks recorded and mixed in Audacity. A bit rough around the edges, but it shows some of what the synth can do.

Undulations.mp3 - I used the looping envelope generator as a kind of sequencer, and set it going with 4 notes played at fairly long intervals - then twiddled knobs for 15 minutes! It's a kind of relaxing, hypnotic piece.

Happy days! :)

knockman
KVRAF
1847 posts since 21 Feb, 2004 from somewhere! anywhere!

Re: ArcSyn-0 - polysynth built with a Raspberry Pi Zero

Post Sat Jan 04, 2020 2:56 pm

:hail: Wow! That sounds fantastic!

Very impressive - I wish I had the skills (i.e.patience to learn how) to code.

Do you make your code available? or should we wait for the Behringer clone :lol:

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kryptonaut
KVRian
751 posts since 25 Apr, 2011

Re: ArcSyn-0 - polysynth built with a Raspberry Pi Zero

Post Mon Jan 06, 2020 2:27 am

Thanks Knockman - I wish I had your woodworking and UI skills! Out of interest, what do you use for the lettering on your projects, for example your Hougaku Conductor mod?

I don't think the code in my synth is in a fit state for public consumption, so we'd better wait for the clones to materialise :) But if anyone has specific questions about the code then I'd be happy to answer.

knockman
KVRAF
1847 posts since 21 Feb, 2004 from somewhere! anywhere!

Re: ArcSyn-0 - polysynth built with a Raspberry Pi Zero

Post Tue Jan 07, 2020 4:01 pm

I have two methods for lettering - inkjet printer decals which are fiddly but look better if enough care is taken to get them aligned, or printing the whole panel on paper and adhering it to the enclosure - this works best for dark backgrounds and light lettering such as the Hougaku Conductor but you need to take care since the paper can expand, easily tear when using water based glues. I've started using a contact adhesive.
In both cases, I spray them with a matte acrylic lacquer but the decals can react to the lacquer and bleed so it's best to seal them beforehand.
The upshot of all this is making the enclosures takes longer than anything else.

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kryptonaut
KVRian
751 posts since 25 Apr, 2011

Re: ArcSyn-0 - polysynth built with a Raspberry Pi Zero

Post Thu Jan 09, 2020 6:43 am

Thanks knockman, that's useful information. I wasn't aware of that inkjet-printable decal paper, I'll have to get myself a few sheets. Definitely agree that making enclosures is a time-consuming business!

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GaryG
KVRAF
5913 posts since 13 Jan, 2003 from Kent, UK

Re: ArcSyn-0 - polysynth built with a Raspberry Pi Zero

Post Wed Feb 12, 2020 5:49 am

Wow, really impressive. Sounds good too.

Re: lettering, you may want to have a look at waterslide transfers too, I know people who use them on DIYguitar pedals with great results. Inkjet or laser varieties.
()_()
(O.o)
(")(")

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autodafe
KVRian
1383 posts since 17 Jul, 2001 from Milan, Italy

Re: ArcSyn-0 - polysynth built with a Raspberry Pi Zero

Post Tue Mar 17, 2020 6:22 am

very nice. will you post eschematics and/or code? thanks

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