I had to implement all DX7 algos to be able to read the preset. PreenFM algo from 10 to 27 are the same as the 32 DX7 algos.
DX7 algos can be different only because of the place of the feedback (See attached picture).
As the PreenFM2 does'nt have feedback it needs less algo. High feedback value can be simulated by selecting a different waveform of the operator.
What i'll try to do is to have the presets sounding better (not closer the DX7), at least by removing the digital noise that occure in too many presets...
Bad sounding DX7 preset can often be solved by manually decreasing modulation indexes and frequency of the oscilators in the highest positioned operator. Press ENG + MENU to have a quick look at the algo. Operator 5 & 6 are often guilty.
Reseting "fine tune" in the oscillator can also help.
Keep in mind that many presets use corner case or even bug of the DX7 to sound as they do. I learnt that by studying Hexter code (
http://dssi.sourceforge.net/hexter.html)
The PreenFM2 will never be able to emulate that
Xavier