I am very new to FM synthesis so sorry if this question is really basic. I have been enjoying experimenting with it in equator and decided to learn more about it, but am having trouble seeing how what I have learned applies in equator.

The explanations I have read talk about ratios, but equator does not seem to have that, instead it has + or - 48 semitones (the same used for tuning the oscillators in non-fm synth), that is easy enough for octave ratios (12/24/36/48) but how do other ratios work when the semitones are 12-TET tuning, is it a combination of using the course and fine tuning, so to get a 2/3 ratio adding 7 semitones and then adjusting the fine tuning to get it perfect?

Also reading about the Yamaha DX the lowest ratio is 0.5, one octave down, whereas the roli can go 4 octaves down, this makes me wonder if I have misunderstood and the tuning is not the same as the ratios in other FM synths, or is it that equator just has a wider parameter for ratios. Also what are the 'depth' controls for A and B, how is this different from the amplitude of the modulator oscillators

## robindra neogi

I am very new to FM synthesis so sorry if this question is really basic. I have been enjoying experimenting with it in equator and decided to learn more about it, but am having trouble seeing how what I have learned applies in equator.

The explanations I have read talk about ratios, but equator does not seem to have that, instead it has + or - 48 semitones (the same used for tuning the oscillators in non-fm synth), that is easy enough for octave ratios (12/24/36/48) but how do other ratios work when the semitones are 12-TET tuning, is it a combination of using the course and fine tuning, so to get a 2/3 ratio adding 7 semitones and then adjusting the fine tuning to get it perfect?

Also reading about the Yamaha DX the lowest ratio is 0.5, one octave down, whereas the roli can go 4 octaves down, this makes me wonder if I have misunderstood and the tuning is not the same as the ratios in other FM synths, or is it that equator just has a wider parameter for ratios. Also what are the 'depth' controls for A and B, how is this different from the amplitude of the modulator oscillators