Thanks for the update and corrections to my thoughts and ideas. It is particularly useful to know that I can change what FS does by changing parameters in the sound fonts.
At the moment I just want something that works so that I can experiment with it. My code does not produce ANY modulation at present and you say the modulator may be disabled in the sound font. I have examined several of my sound fonts using viena and cannot see any way to positively DISABLE any modulators. (I am not a sound font expert, normally just a sound font user - but ready to learn).
However the modulators can be altered and in some cases the default frequency has been altered for particular instruments.
I am attaching one of the sound fonts in which fluidsynth and my code fails to activate any modulation or vibrato. All of the sound fonts I regularly use accompany eplayOrgan when it is downloaded and installed.
Any advice on enabling/disabling modulators will be gratefully received.
I have googled "fliudsynth christian" and surprisingly there were some results connecting the two but nothing obviously of any value to my problem/s. So - how do I get Christians advice on tremolo?
David (csw900)
201606esteyDB-0.sf2