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Update on Juno 2 emulator

Hi there,

A quick note on the Alpha Juno-2 emulator I working on, It’s far from finished but you can check it here:

It converted the Juno-2 presets to a .snaps ; you can play a little bit with it :slight_smile:

What’s done :

  • waveforms (DCO) ,
  • LFO, plugged to DCO
  • VCF

What’s working, but not like J2 :

  • basic HPF filter
  • VCA / VCF Envelope

Whats remains to be done :

  • LFO on VCF
  • correctly emulate HPF
  • correctly emulate VCF env
  • Dynamics, bend, portamento
  • a thousand of other things

the code is far from clean, probably not optimized, but it’s cool, I learn as I go (that’s the goal !)


Great work. Some really nice presets!

Can you explain how you are getting the data to fill your arrays from your Juno? That’s cool, but how exactly are you doing it?

I plug my juno to my computer and I use sonic-visualiser ( in order to measure the data.
Most of the Juno-2 settings are 0-127. I usually take samples each 10. For instance if I want to measure the attack, I take a square oscilator in C3 and take samples at 0, 10, 20… :

I can have a approximate measure of the relation seconds <-> Juno setting. Afer I use google sheet with the interpol add-on (
in order to fill the gaps

I copy-paste the data on a file, a quick awk and I can put it directly into the csd

It’s not perfect, but at least I have something to begin with, and far better than my previous method (by hear :rofl:)

Thanks for sharing. It’s a very interesting approach.

Hi Michael.

I tested this synth yesterday and I must say it’s absolute gold! It really has that 80s analog sound and feel.

I lost two hours yesterday while testing it’s presets and I really enjoyed it. This is probably my favorite synth now. :slight_smile:

However, in some presets there is strong clipping when I play more than one note. I will provide some examples to the github issues.

Thanks for the feedback :slight_smile:
I uploaded a new version adding chorus and correcting a few things, don’t hesitate to try it !
I also uploaded another tone bank (the “memory” Juno-2 bank) just rename it alpha-juno2.snaps


Love it <3 The Juno 2 was my first synth as a kid and that “Synth Brass” preset was indeed a favorite that I tried to reproduce in the song Papageno on Spotify etc.
I have a vague recollection that I somehow managed to send presets etc via sysex midi to my amiga back in the days… Hmm. maybe there’s a sysex “data set” somewhere that could be used. However, the work via ‘’ and a data sheet is just marvelous. Keep up that great creativity.

I think @Michel has now added a way of grabbing the presets from the JUNO and passing them to his clone?

Yes, I coded a small opcode that read sysex and I included factory presets in the emulator.
I’m still coding the “save” part.
There are plenty of presets available here:
I test some of them and they work with my emulator :slight_smile:
(not all of them work, though… :-/)

This is the new repository (and new name !) for my Alpha Juno 1 / 2 MK-50 emulator : June-21

What’s done :

  • Load from syx extracted from Juno’s
  • waveforms (DCO)
  • LFO, plugged to DCO
  • VCF
  • HPF filter
  • VCA / VCF Envelope
  • LFO on VCF

Whats remains to be done :

  • Dynamics for VCF & DCO
  • Bend, portamento, aftertouch
  • Some sounds are not working
  • general sound improvement
  • Save presets

Have fun !

A quick update on things implemented :

  • Dynamics on VCF
  • pitch bender
  • emulation is globaly more accurate, more tones sound as intended
  • presets can be saved

Cheers for New Year’s Eve !

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That’s a nice NY gift! Thanks :wink:

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