On Thu, 29 Apr 2021 08:51:04 +0200 ORL <orl(a)ammd.net> wrote: Thanks for you reply. However, I'm not talking about microtonality in general, but the specific case of the Eq.T control knob in the part engines that is only active when the 440Hz checkbox is ticked. As it happens, I've had answers from elsewhere. It seems people are using it for experimental sounds, and also when they want enharmonic, but key/pitch related sounds for things like percussive instruments. -- Will J Godfrey https://willgodfrey.bandcamp.com/ http://yoshimi.github.io Say you have a poem and I have a tune. Exchange them and we can both have a poem, a tune, and a song.

On Fri, 30 Apr 2021 16:46:22 +0200 Fons Adriaensen &lt;fons(a)linuxaudio.org&gt; wrote: At zero all notes sound 440Hz. As you wind it up they start to spread apart either side of MIDI A4, at the half way point The scale becomes the same as normal equal temperament. Beyond that the law changes and the pitch spread is dramatically greater. The actual code (in the SubSynth engine) is: notefreq = 440.0f; int fixedfreqET = pars->PfixedfreqET; if (fixedfreqET) { // if the frequency varies according the keyboard note float tmp = (midinote - 69.0f) / 12.0f * powf(2.0f, (((fixedfreqET - 1) / 63.0f) - 1.0f)); if (fixedfreqET <= 64) notefreq *= powf(2.0f, tmp); else notefreq *= powf(3.0f, tmp); } -- Will J Godfrey https://willgodfrey.bandcamp.com/ http://yoshimi.github.io Say you have a poem and I have a tune. Exchange them and we can both have a poem, a tune, and a song.