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...

Based on the feedback on beta 2022 (1) there have now been some final additions, changes and fixes, most significantly: Typos and updates of the User Manual Fix for modulation delay glitches on new notes Documented MIDI specification for tool development Various small UI fixes Link to the beta 2022 (2) . If nothing unexpected happens, this will be the release in early July.  But there is one more thing.  Proof reading challenge : if you feel you have the time to read the beta 2022 (2) manuals with scrutiny I vow to donate 50 cents to medecins sans frontieres for every misspelling, typo or grammar mistake that is sent to me. This is not because I feel infallible, but rather that I'd like to see those typos gone and do something meaningful at the same time. Just drop me a message with list of findings. Thanks to all active contributors and also for the interest  from around the world  in this Prophet 600 blog. 

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 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 ...

  -- Firmware Development News -- The alpha development is almost finished! This will be followed by a few weeks of beta testing with selected users. The main changes compared to GliGli version 2.1RC3 are New and comprehensive user manual User Control NEW: panel switchable between GliGli and the original Sequential Circuits layout (Mix/Glide) Better responsiveness and smoother action of controls in general Pick-me-up mode (move controls to the stored patch value before they can take effect) Patch management mode  Patch features New envelope routing Revised envelope shapes, inspired by Prophet 5 rev 1/2 Super accurate fine tuning of oscillator A vs. B LFO sync to arpeggiator and sequencer Totally revised vintage function MIDI functions  local off mode extension of MIDI control