Prophet 600 firmware upgrade revisited

The v2022 firmware is completed and ready for download! There is even a collection of 100 patches compiled from dedicated contributions of Prophet-600 users (and myself) and including some selected Z80 patches. Official download page:  Prophet-600 v2022 firmware + patch collection + documentation Share your opinion on the firmware and the patches here. I will provide some means of structured feedback in the next months to collect your experience out in the field. Then there is also the list of great feature ideas on the backlog which need user prioritization. So if you want to stay informed or even get involved please watch this space or follow my blog.

While I intended to basically release the beta 2022 (2) and only do the smallest and most urgent fixes (hoping of course there would not be any) some very important code changes did came up which now lead up to the improved first release candidate v2022 RC1 ( download ). What happened and what is new?  Apart from those aforementioned small corrections (thanks to the contributors!) there are 2 new features and one really exciting major fix.  The 2 selected features that "sneaked in"were 1) vibrato has now the option to modulate only one of the two oscillators (parameter 222) and 2) the LFO can now be re-triggered when a new key is played (parameter 111) Now to the major fix "tuned pitch shift" : the poly-mod envelope pitch shift of OSC A as well as the LFO pitch shift of OSC A and B are now fully tuned and harmonic. Yes, that wasn't true before. In prior firmware versions tuning was not taken into account so that pitch shifts were detuned depending on how far the...

While the old Z80 based Prophet 600 has a software execution problem, the Teensy++ 2.0 based version has a hardware bottleneck: the multiplexers. Already during the alpha testing phase it was interesting to explore the software performance on different units. When performance tuned too hard you get effects of glitching, e.g. intermittent wrong voltages especially during fast pitch changes. Through structured testing we managed to pin it down to the multiplexers, which incidentally were different in all testing units. Now with the beta, there has been one case in which one voice never properly updated - and interestingly the same unit works fine with the 2015 GliGli version, but not with the (considerably tuned) 2022 beta. As that problem, too, was solved by replacing the multiplexers, I thought it is time to post something about the importance of the multiplexers in the Prophet 600 so other can benefit from it. In short: if you have CD4051BE multiplexers (from Texas Instruments), w...

The problem is as old as the invention of patch storage: once you load a patch into the active synth parameters you run into a conflict with the panel controls. These become detached from the patch. Different solutions have been found over the years.  Jupiter 4 : the brute force approach means that if you store a patch you can never change it again. Yes, really! When a patch is selected, the panel controls have no effect whatsoever. I am sure there is more than one person who was close to a heart attack thinking that their Jupiter 4 was totally broken when first experiencing this... One parameter select : with the entry of the DX7 the single parameter editing UI concept became popular where you select parameter to see its value in a display and then use a universal dial or slider to change it. A nuisance, of course, but solving a lot of problems for synth designers, one of many being that the values can always be updated from memory without conflict... Endless dials : a more modern...

Dear all users of an upgraded Prophet 600, The beta release for the 2022 firmware upgrade is now available! You can download the code and new User Manual here:   Release v2022-beta.1 · image-et-son/p600fw (github.com) . *** NOTE: this is a beta release and it is therefore not the final release but rather very close to it ***  *** NOTE: the code and manuals come with no warranty whatsoever, you carry out updates at your own risk. Always secure patches before updating the firmware. ***  Note: in case you're totally new to the GliGli upgrade you would need to modify your Prophet 600. In this case you should consult the documentation provided by GliGli. GliGli's Prophet 600 blog ( My Synthesizer stuff: p600fw (gliglisynth.blogspot.com) ) contains the links to the technical manual. If you're already running version 2.0 or version 2.1 RC3 you should be familiar with the upgrade procedure either by USB or by MIDI. Please also refer to the User Manual. If you want to activel...

The GliGli firmware (versions 2.0 and 2.1RC3) re-designated the original "Mixer" and "Glide" of the Prophet 600 knobs to control the volumes of oscillators A and B separately. This has the disadvantage that the glide amount needed to go into the - not very user friendly - parameter menu. On the other hand with the GliGli layout, one could (over-)drive both oscillator A and B amps. Personally, I also appreciate the clarity of controlling the two volumes with the two knobs, conveniently positioned next the oscillator sections. There are obviously good reasons for either choice of layout. Now, I have had requests from several users that the original Sequential Circuits layout be brought back. I even had one collector who said he refused the GliGli upgrade because he didn't like the fact the panel control descriptions don't match the control function. And he has a point - not many people got hold of a synth graphics panel overlay to match the GliGli upgrade and ...