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 !

One more alpha (nov 2)

It's just bug fixes and minor adjustments this time (as I said in my previous post, next stable release is nearing).

You can look there for the list of changes: https://github.com/gligli/p600fw/commits/master

Download links at: http://sfx.gligli.free.fr/zik/p600/dev/2013-11-02_2/

Today's P600fw alpha (october 26)

I took a bit of time to merge changes I made in overcycler back in P600fw, and also added a few missing features.

Here are all the changes I made:

• Overall speedup: refresh rate at full load is now twice faster.
• Various fixes, especially in the assigner.
• MIDI in pitch bend & modulation wheel messages support.
• MIDI out is now sending note on/off, pitch bend and modulation wheel messages.
• Footswitch support, can be used to latch new chords in unison mode, and to hold the current arpeggio while arpeggiating.
• External clock support for the arpeggiator, clock source can be changed using "From tape" + 8 (either MIDI clock, or pulse clock sent into "Cassette in". You can then choose the actual arp clock ratio using the "Arpeggiator speed" parameter, from 1/3 to 1/384).

Also, here's a description of the new user interface commands:

• In manual mode, or by pressing "To tape" in preset mode, you get access to 20 extended parameters (2 per keypad number), the "Speed" potentiometer edits the last chosen one.

Keypad #	Parameter name	Choices
First press
0	Arpeggiator speed	-
1	LFO shape	pulse-triangle,random-sine,noise-saw
2	Vibrato speed	-
3	Vibrato amount	-
4	Modulation delay	-
5	Amplifier envelope shape	fast-exp,fast-lin,slow-exp,slow-lin
6	Bender target	off,vco,vcf,vca
7	Glide	-
8	Unison detune	-
9	Amplifier velocity amount	-
Second press
0	Arpeggiator speed	-
1	LFO osc a/b target	ab,a,b
2	LFO speed range	low,high
3	Modulation wheel range	min,low,high,full
4	Modulation wheel target	lfo,vibrato
5	Filter envelope shape	fast-exp,fast-lin,slow-exp,slow-lin
6	Bender range	3rd,5th,Octave
7	Assigner priority mode	last,low,high
8	Osc pitch mode	free,semitone,octave
9	Filter velocity amount	-

• Anytime, by maintaining "From tape" and pressing a keypad number, you get access to misc functions.

Keypad #	Function name	Choices
1	MIDI receive channel	omni,1-16
2	MIDI send channel	1-16
3	Calibrate bender	-
4	Select voice	1-6
5	Kill selected voice	on,off
6	Dump presets	-
7	Set basic saw patch	-
8	Set clock source	internal,MIDI,tape

Download links at: http://sfx.gligli.free.fr/zik/p600/dev/2013-10-26_2/

A new stable release should be out soon, so please report any problem you could find. Using github issues (http://github.com/gligli/p600fw/issues) for this would be cool.

EDIT: Built a new version that seems to fix "ghost" tones people had in post-beta1 versions.

Overcycler, the software

I worked on the software these last days, it's of course based on a good chunk of P600fw (envelopes, lfo, assigner, midi, storage, ...)

Besides a few PCB bugs I worked around in software, or using the soldering iron, the hardware works great :D

The microcontroller is really powerful, which allowed me to use very high sample rates (90Khz wih 2x oversampling, so effectively 45Khz), there is very little aliasing up to the highest MIDI notes.

Something I wasn't sure about was CV sample and hold performance (basically, it's a modern simplified version of the Prophet 600 design).
I was happy to see that it's very stable, and slew rate is great :)
 Here's a VCA envelope example:

 We can see that the fastest attack speed is below 100 microseconds (most analog synthesizers are 10 times slower !).

Noise was a problem at first, but  using various tweaks, it got much better (signal to noise ratio goes from 50db for oscillators to 100db for the master mixer now).

--

Here's a little demo I made recently: http://sfx.gligli.free.fr/zik/overcycler/overcycler3.mp3
(Simple saw patches, I can't use the potentiometers to tweak the sound for now)

And an older one: http://sfx.gligli.free.fr/zik/overcycler/overcycler2.flac
(I had noise problems at that time, but it' a better raw sound demo)

I also set up a github repository for code and schematics: https://github.com/gligli/overcycler
(PCBs are still buggy tho)

PS: That's all for now, have a nice read :)