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image-et-son / p600fw

GliGli based Prophet 600 firmware upgrade
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Take tuning into account for poly-mod and LFO pitch shift #70

Closed image-et-son closed 2 years ago

image-et-son commented 2 years ago

At the moment the frequency CV equivalent from poly mod and LFO is simply added to the tuned oscillator CV (see function refreshVoice() around lines 940 etc.). Variations in chip characteristics, are compensated by tuning but this is not taken into account. This leads to strongly untuned shifts. The change will affect old patches, but it is fair to assumed that almost no user has actively worked with the imperfections of this, in particular since this is also voice dependent. Note also that the Z80 firmware takes tuning properly into account, see for example orginal preset number 5.

image-et-son commented 2 years ago

Horray, a new synth is born. Completely new patches are possible due to harmonic shifting. For those eager to try out: try the two patches with an older version (sounds horrible) and then with the attached release candidate 1 (sounds harmonic). p600firmware_v2022_RC1_20220715.zip 2_patches_with_harmonic_shift.zip

image-et-son commented 2 years ago

Hm, I just found out that the tuning depends on the instrument. So it needs tweaking if I use it on my second P600. Need to think about it - I would have thought that tuning takes care of this. So this is not the end of the story (yet).

matrix12x commented 2 years ago

I tested both patches on the prior Beta and they don't sound too good. I updated to the version you have posted above and they sound in tune. Patch 01 sounds amazing.