New DIY project: standalone Juno-60 chorus clone

I sold my JX-3P a while ago, but I found out I missed its chorus.
So I decided to clone it, and since the Juno-60 one is often described as better, this is the one I chose as a basis.

All components are still available, except maybe the BBDs, but you can source them from chinese ebay sellers, and they seem to be genuine.
All I did was to change input & output stages, and use a LFO design inspired from the BOSS CE-2, the remaining parts stayed mostly the same.


Enough said, here's the finished PCB:

And here's how it sounds (base sound from my Prophet 600):


Some more files: sfx.gligli.free.fr/zik/juno-chorus-clone/juno-chorus-clone.7z (pics, schematics, FLAC demo)
And, since it's a free/open source project, the project page: http://github.com/gligli/juno-chorus-clone

The debug phase went mostly well, but I still have to update the PCB from the fixes I made on the schematics, so better wait a little if you want to build one!

Edit:
PCB update done, should be ok to build!

Edit2:
I compared it with a Juno-60 recording and found out the chorus was a bit weak on mine. Turns out I copied a resistor value wrong in the BBDs output stages.
I fixed it and now it sounds really close to the original!

Edit3:
Some more changes to input and output levels.
Here's a second demo on polyphonic & arpeggio sounds:

New P600fw alpha (april 20)

Notable changes:

- More tuner tweaks, filter tuning got much better on my P600 (to the point of having almost perfect filter unison).
- Modulation delay improvements: after the modutation delay, modulation increases exponentially over a period of time equal to the modulation delay.
- Added "whole tone" bender range (parameter value is "2nd").
- Assigner legato fixes.

Download links at: http://sfx.gligli.free.fr/zik/p600/dev/2014-04-20/

P600fw MIDI CC map as of today

Here it is: http://sfx.gligli.free.fr/zik/p600/midi_cc_map_2014_04_07.pdf

As usual, continuous parameters have both a coarse and a fine CC, to get full 14bit precision.

"Stepped" parameters work by dividing the 0-127 range is as many zones as there is choices for the parameter.
Eg: "Unison" is off for 0-63 and on for 64-127.

New P600fw alpha (march 17)

This one brings some nice improvements and a few bugfixes:

- When an extended parameter is selected, its current value is displayed.
- Modulation delay (eg. on vibrato) now has a progressive start (about half a second until full level is reached, seems nice and musical to me, but I'm open to suggestions).
- Many fixes to unison mode, should be much more stable now.
- Slowed down text scrolling a little, to help readability.
- Misc. other bugfixes.


Download links at: http://sfx.gligli.free.fr/zik/p600/dev/2014-03-17/

New P600fw alpha (march 9)

This time I tried to get my frequency measurement routine for the tuner closer to the way it's described in the service manual, hoping that it would fix the remaining tuning problems.

If it gets better or worse, please let me know...

Download links at: http://sfx.gligli.free.fr/zik/p600/dev/2014-03-09/

New P600fw alpha (march 1)

I didn't have much time to dedicate to my synthesizer projects these last months, but here's a new alpha of P600fw with the following changes:

- Fixed broken exponential envelopes interpolation (was causing stepping).
- Removed MIDI soft-thru (it wasn't an intended feature).
- Added 1/1 and 1/2 arpeggiator external clock ratios (usefull for tape sync).
- Made minor tweaks to the tuner.

Download links at: http://sfx.gligli.free.fr/zik/p600/dev/2014-03-01/

Overcycler patches demo

I recently added a lot of what was missing to make it usable, I still need to handle multitimbrality and write a sequencer, but it's already a fully working polysynth ! :)

As you can hear in this demo, it's very versatile, from huge analog pads to gritty digital sounds, going through all the inbetween possibilities. A great addition to my other analog synths !